Engine Controls - Tests W/codes - Eec-Iv Lincoln Mark VIII I

INTRODUCTION

Perform all steps in BASIC TESTING - 4.6L article. If no fault is found while performing BASIC DIAGNOSTIC PROCEDURES, proceed with self-diagnostics. If no diagnostic trouble codes or only pass codes (system functioning properly) are found during self-diagnostics, proceed to the TESTS W/O CODES article for diagnosis by symptoms.

DIAGNOSTIC FORMATS

QUICK TEST and CIRCUIT TESTS are diagnostic formats used to test and service EEC-IV system. QUICK TEST allows technician to identify problems and retrieve diagnostic trouble codes. CIRCUIT TESTS check circuits, sensors and actuators.

Before starting any CIRCUIT TEST, follow all steps under QUICK TEST to find correct CIRCUIT TEST to perform. If vehicle passes QUICK TEST and no driveability symptoms or intermittent faults exist, EEC-IV system is okay.

DIAGNOSTIC TROUBLE CODES (DTC)

During QUICK TEST, 3 types of diagnostic trouble codes are retrieved: KOEO, KOER and Continuous Memory codes. See QUICK TEST for self-test procedures. Codes may be cleared from PCM memory after they have been recorded or repaired. See CLEARING CODES .

KOEO & KOER Codes (Hard Faults)

These codes indicate faults are present at time of testing. A hard fault may cause CHECK ENGINE or Malfunction Indicator Light (MIL) to go on and remain on until fault is repaired. If KOEO or KOER codes are retrieved during KOEO SELF-TEST or KOER SELF-TEST, use DIAGNOSTIC TROUBLE CODE REFERENCE CHARTS to find correct testing and repair procedures.

Continuous Memory Codes (Intermittent Faults)

These codes indicate a fault that may or may not be present at time of testing. These codes are used to diagnose intermittent problems. Continuous Memory Codes are retrieved after KOEO SELF-TEST. Some codes may turn on MIL/CHECK ENGINE light. Corresponding intermittent fault trouble code will be retained in PCM memory. If fault does not reoccur within 40 warm-up cycles, PCM will automatically clear code.

After noting and/or repairing fault, clear codes from memory. See CLEARING CODES . Intermittent faults may be caused by a sensor, connector or wiring-related problem. See INTERMITTENTS in the TESTS W/O CODES article.

RETRIEVING CODES

Diagnostic trouble codes are retrieved from EEC-IV system through Data Link Connector (DLC). Various methods and test equipment may be used to access these codes

1. Analog Volt-Ohmmeter (VOM)
2. Scan Tester
3. Malfunction Indicator Light (MIL)/CHECK ENGINE Light
4. STAR Series Tester

DATA LINK CONNECTOR (DLC) LOCATIONS

KOEO & KOER SELF-TEST Codes

PCM outputs codes one digit at a time. Record codes in order received. These codes indicate current faults in system and should be serviced in order of appearance. Use DIAGNOSTIC TROUBLE CODE REFERENCE CHARTS to identify correct CIRCUIT TEST to perform.

If using an analog voltmeter or MIL/CHECK ENGINE light, pay careful attention to length of pauses in order to read codes correctly. Digits in DTC will be displayed by a needle pulse sweep (analog voltmeter) or a flash (MIL/CHECK ENGINE light).

Diagnostic Trouble Codes (DTCs) are represented by a 3-digit number. For example, the first digit of DTC 312 would be displayed by 3 sweeps/flashes with a 0.4-second pause in-between each sweep/flash. A 2-second pause will occur between first and second digits of DTC. Second digit of DTC would be displayed by one sweep/flash then another 2-second pause. Third digit of DTC would be displayed by 2 sweeps/flashes with a 0.4 pause in-between each sweep/flash. A 4-second pause occurs between each code. (Scheme 12) KOEO codes are separated from Continuous Memory codes by a 6-9-second delay, a 0.4-second sweep/flash (separator pulse) and another 6-9-second delay. (Scheme 13)

Scan tester, if used, will count pulses and display them as a digital code. STAR tester cannot be used to read 3-digit codes. Super Star II or New Generation Star tester can be used to read 3-digit codes. If using Super Star II tester, 3-digit codes will only be displayed in fast code mode. If slow code mode is used, display will be blank.

Engine Identification (ID) Codes

Engine ID codes are issued at beginning of KOER SELF-TEST. Codes are one-digit numbers represented by number of pulses displayed. (Scheme 13) Engine ID code is equal to one-half the number of engine cylinders. For example, 2 pulses would indicate that engine is a 4-cylinder. ID code is used to verify proper PCM is installed and that SELF-TEST has been entered.

Separator Pulse

Single 1/2-second separator pulse is issued 6-9 seconds after last KOEO code. Continuous Memory Codes (intermittent faults) are then displayed 6-9 seconds after 1/2-second separator pulse.

Pass Codes

A Code 111 indicates no diagnostic trouble codes were recorded in that portion of test; system passes that portion of test. If Code 111 is not retrieved in KOEO SELF-TEST, codes retrieved during KOER SELF-TEST may not be valid. Code 111 (pass code) must be obtained in KOEO SELF-TEST. A Code 111-1-111 output during KOEO SELF-TEST indicates no KOEO code or Continuous Memory Code was recorded.

Continuous Memory Codes

These codes result from information stored by PCM during continuous self-test monitoring. Codes are displayed after separator pulse code in KOEO SELF-TEST. Use these codes for diagnosis only when KOEO SELF-TEST and KOER SELF-TEST result in Code 111 (pass code) and all steps under QUICK TEST are successfully completed. (A few codes are exceptions which may be checked after KOEO codes have been repaired). These codes indicate faults recorded within last 40 engine starts. Fault may or may not be currently present. See DIAGNOSTIC TROUBLE CODE REFERENCE CHARTS .

Fast Codes

At start of KOEO SELF-TEST and after Wide Open Throttle (WOT) request in KOER SELF-TEST, PCM outputs short bursts of information, known as FAST CODES, which were used by manufacturer during assembly. These codes contain the identical information as slow codes, but are transmitted at 100 times the normal rate. With most equipment (except Super Star II tester), these code bursts are not visible. An entire code sequence lasts for less than1/2 second.

Scheme 12

Scheme 13

CLEARING CODES

To clear codes from PCM memory, start KOEO SELF-TEST . When diagnostic trouble codes appear on test equipment or MIL/CHECK ENGINE light, disconnect jumper wire from Self-Test Input (STI) connector. If using STAR Series Tester, unlatch center button. This procedure erases Continuous Memory Codes from PCM memory. If problem has not been corrected or fault is still present, hard code will immediately be reset in PCM memory.

Description

Following procedures are functional tests of EEC-IV system. These 5 basic test steps must be followed in sequence to avoid misdiagnosis

1. Visual Check
2. Equipment Hookup
3. KOEO (Key On Engine Off) SELF-TEST
4. KOER (Key On Engine Running) SELF-TEST
5. Continuous Monitor Mode (Wiggle Test)

Diagnostic Aids

After each service or repair procedure has been completed, repeat QUICK TEST to ensure all EEC-IV systems work properly and diagnostic trouble codes are no longer present.

VISUAL CHECK

Complete all steps in the BASIC TESTING - 4.6L article before proceeding to self-diagnostic tests. Ensure all vacuum hoses and EEC-IV wiring harnesses are properly connected.

EQUIPMENT HOOKUP

Apply parking brake, and place shift lever in Park (A/T) or Neutral(M/T) position. Block drive wheels. Turn off all electrical accessories. Connect appropriate test equipment to vehicle as follows

Scheme 14

1. Turn ignition off. Set VOM at 0-15V DC range. Connect positive lead of VOM to positive battery terminal.
2. Connect negative VOM lead to Self-Test Output (STO) terminal of Data Link Connector (DLC). (Scheme 14) Go to «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test). Activate KOEO SELF-TEST by connecting jumper wire from Self-Test Input (STI) pigtail to signal return (SIG RTN) terminal at DLC with ignition on.

Scan Tester

Follow manufacturer's instructions to hook up equipment and record diagnostic trouble codes.

STAR Series Tester

Turn ignition off. Connect color-coded adapter cable leads to diagnostic tester. Connect 2 service connectors of adapter cable to vehicle Data Link Connector (DLC) and STI pigtail connector. If using Super Star II tester, select EEC-IV and Fast modes. On all models, go to KOEO SELF-TEST .

CHECK ENGINE Light/Malfunction Indicator Light (MIL)

Turn ignition on. Connect a jumper wire between Self-Test Input (STI) pigtail and signal return (SIG RTN) terminal of Data Link Connector (DLC). (Scheme 15) Go to KOEO SELF-TEST.

Scheme 15

KOEO SELF-TEST

Ensure engine is warmed to normal operating temperature. If engine does not start (or stalls after starting), continue KOEO SELF-TEST . DO NOT depress throttle. Turn ignition off. Ensure test equipment is properly attached. Turn ignition on (engine off). Record all KOEO and Continuous Memory Codes.

If a Code 111 (pass code) is not retrieved, service KOEO codes. See DIAGNOSTIC TROUBLE CODE REFERENCE CHARTS . If PCM will not output codes, go to CIRCUIT TEST QA . If diagnostic trouble codes are retrieved

1. If MIL/CHECK ENGINE light is on, service diagnostic trouble codes in order retrieved. See «DIAGNOSTIC TROUBLE CODE REFERENCE CHARTS»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
2. If Continuous Memory Code 215, 216, 217, 218, 222, 224, 232 or 238 is retrieved during KOEO SELF-TEST, see IGNITION SYSTEM in the «SYSTEM/COMPONENT TESTS»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-46l) article.
3. If vehicle has a no-start condition, go to CIRCUIT TEST AA (DI), CIRCUIT TEST AB (EI - low data rate) or «CIRCUIT TEST AC»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__circuit-test-ac-no-start-ei) (EI - high data rate).
4. If vehicle displays a Code 111 (pass code) and does not have any symptoms described in previous steps, go to «KOER SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .

DO NOT enter this test sequence until a Code 111 (pass code) has been retrieved in KOEO SELF-TEST. If system has not passed KOEO SELF-TEST, codes recorded in KOER SELF-TEST may not be valid.

Deactivate self-test by removing and reconnecting jumper wire or by procedure specified by test equipment in use. Start engine, and run it for 2 minutes at 2000 RPM to warm Heated Exhaust Gas Oxygen Sensor (HO2S). Turn engine off, and wait 10 seconds. Activate KOER SELF-TEST using a jumper wire or appropriate procedure for test equipment used. Start engine. Record all diagnostic trouble codes displayed. Check following items

1. If engine starts and stalls (or stalls during self-test), go to «CIRCUIT TEST S»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
2. If Code 998 is displayed, EEC-IV system is operating in Failure Management Effects Mode (FMEM) and vehicle has not passed KOEO SELF-TEST. Vehicle cannot be diagnosed while in FMEM mode.
3. If vehicle is equipped with a Brake On-Off (BOO) switch, brake pedal must be depressed and released after ID code portion of test.
4. On vehicles with Power Steering Pressure (PSP) switch, turn steering wheel at least 1/2 turn and release within 1-2 seconds after ID code portion of test.
5. If Dynamic Response Code appears, perform a brief Wide Open Throttle (WOT). DO NOT perform WOT unless requested.
6. If a Code 111 (pass code) is retrieved during KOER SELF-TEST, service Continuous Memory Codes retrieved in KOEO SELF-TEST. See «DIAGNOSTIC TROUBLE CODE REFERENCE CHARTS»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
7. If KOER codes are present, see «DIAGNOSTIC TROUBLE CODE REFERENCE CHARTS»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If system will not output codes, go to «CIRCUIT TEST QA»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
8. If a Code 111 (pass code) is retrieved during Continuous Memory Code portion of KOEO SELF-TEST and no driveability problem exists, EEC-IV testing is complete. If driveability problems are still present, go to the «TESTS W/O CODES»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wo-codes) article.
9. If a Code 111 (pass code) is retrieved during KOER SELF-TEST and intermittent fault(s) continue, go to «CONTINUOUS MONITOR MODE (WIGGLE TEST)»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__continuous-monitor-mode-wiggle-test) .

CONTINUOUS MONITOR MODE (WIGGLE TEST)

Continuous Monitor Mode allows technician to attempt to recreate an intermittent fault while monitoring system. This mode, also called wiggle test, may be used in both KOEO SELF-TEST and KOER SELF-TEST. CIRCUIT TESTS specify use of this procedure to identify intermittent faults in specific circuits or components.

KOEO Wiggle Test Procedure

Connect test equipment. (Scheme 14)or (Scheme 15). Turn ignition on. Activate self-test using jumper lead or diagnostic tester. Wait 10 seconds, and then deactivate and reactivate self-test. Wiggle test mode is now activated. Tap, move and wiggle suspect sensor and/or harness area. If a fault is detected, a diagnostic trouble code may be stored in memory and indicated at diagnostic tester or scan tester. Retrieve code, and perform appropriate test. See DIAGNOSTIC TROUBLE CODE REFERENCE CHARTS.

KOER Wiggle Test Procedure

Connect test equipment. (Scheme 14)or (Scheme 15). Start engine. Activate self-test using jumper lead or diagnostic tester. Wait 10 seconds, and then deactivate and reactivate self-test. DO NOT turn engine off. KOER wiggle test mode is now activated. Tap, move and wiggle suspect sensor and/or harness area. If a fault is detected, a diagnostic trouble code may be stored in memory and indicated at diagnostic tester or scan tester. Retrieve code, and perform appropriate test. See DIAGNOSTIC TROUBLE CODE REFERENCE CHARTS.

ADDITIONAL SYSTEM FUNCTIONS

Additional diagnostic system features are available to help diagnose driveability problems and service EEC-IV systems

Malfunction Indicator Light (MIL)

MIL is intended to alert driver of certain malfunctions in EEC-IV system. Light may also be used to retrieve diagnostic trouble codes stored in PCM. When hooked up for KOEO SELF-TEST or KOER SELF-TEST, light will display all codes which turn on light during vehicle operation.

Light should come on when ignition is turned on and go out when engine is started. If light comes on and then goes off during vehicle operation, code causing light to come on will be stored in PCM memory as a Continuous Memory Code. If light comes on during vehicle operation, vehicle should be inspected as soon as possible. Immediately turning off engine is not necessary; vehicle can be driven with light on.

Output State Diagnostic Test Mode (DTM)

1. Output state DTM is used as an aid in servicing output actuators associated with EEC-IV system. It allows technicians to energize and de-energize most system output actuators on command. This mode is entered from KOEO SELF-TEST after all codes have been retrieved.
2. Disconnect cruise control servo (if equipped). With DVOM on 20-volt scale, connect DVOM negative lead to STO terminal at Diagnostic Link Connector (DLC). Connect positive lead to positive battery terminal. Using jumper wire, connect STI to SIG RTN at Diagnostic Link Connector (DLC).
3. Perform «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) until continuous memory test is complete. DVOM will read less than 1.0 volt when test is complete. Depress and release throttle. If voltage increases, output state DTM has been entered. If voltage does not increase, depress throttle to WOT and release. If STO voltage still does not increase, go to «CIRCUIT TEST QC»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .

Failure Mode Effects Management (FMEM) Code 998

FMEM mode allows system operation when sensors fail or transmit signals that are out of normal operating range. During FMEM mode, PCM substitutes a mid-range signal for defective sensor while continuing to monitor sensor. If faulty sensor's signals return to normal operating range, PCM will use those signals. A Code 998 will be displayed when FMEM mode is in effect.

Hardware Limited Operational Strategy (HLOS)

HLOS mode is used when system fault(s) is too extreme for Failure Mode Effects Management (FMEM) mode to handle. If a number of system or sensor failures are present and PCM is not receiving enough information to operate, PCM will switch to HLOS mode. PCM will output fixed values to allow operation of vehicle. Driveability concerns will be present. PCM will not output diagnostic trouble codes in this mode.

Cylinder Balance Test

This test helps identify a weak or non-contributing cylinder in engines with SFI fuel systems. PCM shuts off fuel supply to each injector and measures RPM drop. It computes variation between cylinders and identifies weak ones.

This test mode is entered from KOER SELF-TEST after all codes have been displayed. Within 2 minutes after codes have been displayed, lightly depress throttle (a 2-3 degree throttle angle is required, not a wide open throttle). After a brief stabilizing period, PCM will activate test procedure.

Test will be repeated if throttle is depressed within 2 minutes of final code output. During second and third test sequences, percentage of allowable variation between cylinders is reduced. Service codes displayed during this test identify weak or non-contributing cylinder. See CYLINDER BALANCE TEST DIAGNOSTIC TROUBLE CODES table.

If Code 90 is displayed during this test, system has passed test. If Code 77 is displayed, repeat cylinder balance test. If throttle is moved during this test, Code 77 will appear, indicating test is not complete. Repeat Cylinder Balance Test. Total test time is about 3 minutes.

CYLINDER BALANCE TEST DIAGNOSTIC TROUBLE CODES

SUMMARY

If no diagnostic trouble code is present but driveability problem still exists, proceed to the TESTS W/O CODES article for symptom diagnostic or intermittent diagnosis procedures.

Diagnostic Trouble Codes Reference Charts (Codes 111-157). Scheme 16

Diagnostic Trouble Codes Reference Charts (Codes 158-185). Scheme 17

Diagnostic Trouble Codes Reference Charts (Codes 186-224). Scheme 18

Diagnostic Trouble Codes Reference Charts (Codes 225-327). Scheme 19

Diagnostic Trouble Codes Reference Charts (Codes 328-512). Scheme 20

Diagnostic Trouble Codes Reference Charts (Codes 513-542). Scheme 21

Diagnostic Trouble Codes Reference Charts (Codes 543-565). Scheme 22

Diagnostic Trouble Codes Reference Charts (Codes 566-625). Scheme 23

Diagnostic Trouble Codes Reference Charts (Codes 626-652). Scheme 24

Diagnostic Trouble Codes Reference Charts (Codes 654-998). Scheme 25

Scheme 26

Scheme 27

Scheme 28

Scheme 29

CIRCUIT TESTS

Note. A breakout box, connected to vehicle harness at PCM, is necessary to perform most circuit tests. References to Test Pin No. found in CIRCUIT TEST steps refer to test terminals on manufacturer's breakout box. Circuit diagrams at beginning of each test identify circuit and wire colors.

HOW TO USE CIRCUIT TESTS

1. Ensure all non-EEC related faults found while performing steps in the «BASIC TESTING - 4.6L»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-basic-testing-46l) article have been corrected. DO NOT perform any CIRCUIT TEST unless specifically instructed by a QUICK TEST procedure. Follow each test step in order until fault is found. DO NOT replace any part unless directed to do so. When more than one code is retrieved, start with first code displayed.
2. CIRCUIT TESTS ensure electrical circuits are okay before sensors or other components are replaced. Always test circuits for continuity between sensor and PCM. Test all circuits for short to power, opens or short to ground. Voltage Reference (VREF) and Voltage Power (VPWR) circuits should be tested with ignition on or as specified in CIRCUIT TESTS.
3. DO NOT measure voltage or resistance at PCM. DO NOT connect any test light unless specified in testing procedure. All measurements are made by probing rear of connector (wiring harness side). Isolate both ends of a circuit and turn ignition off when checking for shorts or continuity, unless instructed otherwise.
4. Disconnect solenoids and switches from harness before measuring continuity and resistance or applying voltage. After each repair, check all component connections and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
5. An open circuit is defined as a resistance reading of more than 5 ohms. This specification tolerance may be too high for some items in EEC-IV system. If resistance approaches 5 ohms, always clean suspect connector and coat it with protective dielectric silicone grease. A short is defined as a resistance reading of 10,000 ohms or less, unless stated otherwise in CIRCUIT TESTS. NOTE: In following tests, circuit diagrams and illustrations are courtesy of Ford Motor Co. CIRCUIT TESTS are grouped as follows: A-C - No Start & Voltage Tests. DA-DT - Input Sensor Tests. FD-FF - Additional Input Component Tests. G-J - Fuel Control Systems. KB-XB - Powertrain Control Module (PCM) Output Tests.

CIRCUIT TEST AC - NO-START EI - DISTRIBUTORLESS IGNITION SYSTEMS (HIGH DATA RATE)

Enter this CIRCUIT TEST only when all steps under QUICK TEST have been successfully completed and engine still does not start or if directed here from another test or chart. This test is only intended to diagnose

1. Powertrain Control Module (PCM).
2. Spark (PCM-controlled).
3. Wiring harness circuits (PIP, IGN GND and VPWR).

To prevent replacement of good components, be aware the following non-EEC related areas and components may be cause of problem

Scheme 30

1. Fuel quality and quantity.
2. Ignition (general condition).
3. Engine mechanical components.
4. Starter and battery circuits.
5. Crankshaft Position (CKP) sensor.
6. Ignition Control Module (ICM).
7. Coil packs. (Scheme 30): Ignition System Wiring Diagram TEST PIN WIRE COLOR IDENTIFICATION Application Wire Color TEST PIN NO. 4 (IDM) Tan/Yellow TEST PIN NO. 16 (IGN GND) Orange/Red TEST PIN NO. 36 (SPOUT) Pink TEST PIN NO. 56 (PIP) Gray/Orange

1. Starting System Ensure fuel pump inertia switch is closed (button pushed in). Try to start engine. If engine does not crank, check vehicle starting and charging systems. If engine cranks, go to next step.
2. Check VREF Signal At TP Sensor Turn ignition off. Disconnect Throttle Position (TP) sensor. Turn ignition on (engine off). Measure voltage between VREF and SIG RTN at TP sensor harness connector. If voltage is not 4-6 volts, go to «CIRCUIT TEST C»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If voltage is 4-6 volts, reconnect TP sensor and go to next step.
3. Check For Spark At Plugs Disconnect any spark plug wire. Connect spark tester between plug wire and engine ground. Crank engine and check for spark. If spark is present, reconnect spark plug wire and go to next step. If spark is not present, check ignition system. See IGNITION SYSTEM in the «SYSTEM/COMPONENT TESTS»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-46l) article.
4. Check IGN GND Continuity Turn ignition off. Disconnect PCM 60-pin connector, and inspect it for damaged pins, corrosion and loose wires. Repair as necessary. Install Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Disconnect Ignition Control Module (ICM). Measure resistance between test pin No. 16 at breakout box and IGN GND terminal at ICM wiring harness connector. If resistance is 5 ohms or more, repair open in IGN GND circuit. Remove breakout box, reconnect components and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If reading is less than 5 ohms, go to next step.
5. Check PIP For Short To Power Ensure ICM and PCM are disconnected. Turn ignition on. Measure voltage between test pin No. 56 at breakout box and negative battery terminal. If voltage is more than 7 volts, repair PIP circuit short to power. Remove breakout box, reconnect components and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If voltage is 7 volts or less, go to next step.
6. Check PIP Circuit Continuity Turn ignition off. Measure resistance between test pin No. 56 at breakout box and PIP terminal at ICM wiring harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open PIP circuit. Remove breakout box, reconnect components and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
7. Check PIP Circuit For Shorts To Ground Ensure ICM and PCM are disconnected. Measure resistance between test pin No. 56 (PIP) and test pins No. 16, 40, 46 and 60 (checking for short to ground). If any reading is less than 10,000 ohms, repair short in PIP circuit. Remove breakout box, reconnect components and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If engine still does not start, go to next step. If all readings are 10,000 ohms or more, go to next step.
8. Isolate Shorts In PCM Ensure ignition is turned off. With breakout box installed, connect PCM to breakout box. Leave ICM disconnected. Measure resistance between test pin No. 56 (PIP) and test pins No. 37 and 57 (checking for short to power). Also, measure resistance between test pin No. 56 and test pins No. 40 and 60 (checking for short to ground). If any resistance is not 15,000-180,000 ohms, replace PCM. Remove breakout box, reconnect components and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If all resistances are 15,000-180,000 ohms, go to next step.
9. Check PIP Signal Turn ignition off. Disconnect PCM from breakout box. Reconnect ICM module. Measure voltage between test pin No. 56 and test pin No. 16 at breakout box while cranking engine. Record voltage. If voltage is 3-7 volts, go to next step. If voltage is not 3-7 volts, replace ICM. Remove breakout box, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
10. Isolate Short In PCM Turn ignition off. Reconnect PCM to breakout box leaving ICM disconnected. Measure voltage between test pin No. 56 and test pin No. 16 at breakout box while cranking engine. Record voltage. If voltage is 3-7 volts, go to next step. If voltage is not 3-7 volts, replace PCM. Remove breakout box, reconnect components and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . CAUTION: Stop this test at first sign of a fuel leak. Do not allow smoking or an open flame in vicinity of vehicle during these tests.
11. Fuel Pump Check Connect fuel pressure gauge to vehicle. Note initial fuel pressure reading. Pressurize fuel system by turning ignition on for one second, and observe pressure gauge. Turn ignition off, and wait 10 seconds. Repeat sequence 5 times. If pressure increases, go to «CIRCUIT TEST S»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If pressure does not increase, go to FUEL SYSTEM in the «SYSTEM/COMPONENT TESTS»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-46l) article.

Perform this test when a check for VREF signal has failed in sensor input CIRCUIT TESTS AA, AB, AC, DA-DR or QA. SIG RTN is a dedicated ground used by most EEC-IV system sensors. VREF is a 5-volt reference voltage that is continuously output by PCM. This consistent voltage signal is used on all 3-wire sensors.

This circuit test is only intended to diagnose the following components and circuits

Scheme 31

1. Powertrain Control Module (PCM).
2. Vehicle wiring harness circuits (SIG RTN and VREF). (Scheme 31): Reference Voltage Circuits & Connector Terminals TEST PIN WIRE COLOR IDENTIFICATION Application Wire Color TEST PIN NO. 26 (VREF) Brown/White TEST PIN NO. 46 (SIG RTN) Gray/Red

1. Check Battery Power Circuit Turn ignition off. Disconnect PCM 60-pin connector, and inspect it for damaged pins, corrosion and loose wires. Repair as necessary. Install Breakout Box (T83L-50-EEC-IV), leaving PCM connected. Turn ignition on. Measure and record voltage between breakout box test pin No. 37 and SIG RTN terminal of Data Link Connector (DLC). Also, measure and record voltage across battery terminals. If both readings are less than 10.5 volts or if they differ by more than 1.0 volt, reconnect sensor (if applicable) and go to «CIRCUIT TEST XB»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If voltages are 10.5 volts or more and do not differ from one another by more than 1.0 volt, go to next step.
2. Check VREF Voltage With breakout box installed and PCM connected, set DVOM on 20-volt scale. Turn ignition on. Measure voltage between test pins No. 26 and 46 at breakout box. If voltage is 4-6 volts, go to next step. If voltage is more than 6 volts, go to step 4). If voltage is less than 4 volts, go to step 5).
3. Check VREF & SIG RTN Circuit Continuity Turn ignition off. Disconnect PCM. If directed here by a sensor test, ensure sensor is disconnected. Measure resistance between test pin No. 26 and VREF terminal at wiring harness connector of applicable sensor. Also, measure resistance between test pin No. 46 and SIG RTN circuit terminal at wiring harness connector of applicable sensor. If both readings are less than 5 ohms, VREF circuit is okay. Remove breakout box, reconnect components and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If either reading is 5 ohms or more, repair open in VREF or SIG RTN circuit. Remove breakout box, reconnect components and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
4. Check For Excess VREF Circuit Voltage Turn ignition off. Ensure PCM is disconnected. With breakout box installed, disconnect scan tester or STAR tester (if applicable). Turn ignition on. Measure voltage between test pin No. 26 and battery ground. If voltage is less than 0.5 volt, replace PCM. Remove breakout box, reconnect components and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If voltage is 0.5 volt or more, repair short to battery power in wiring harness. Remove breakout box, reconnect components and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
5. Check For Shorted TP Sensor Turn ignition off. Connect PCM to breakout box. Disconnect Throttle Position (TP) sensor connector from wiring harness. Turn ignition on. Measure voltage between test pins No. 26 and 46 at breakout box. If voltage is 4 volts or more, replace TP sensor. Remove breakout box, reconnect components and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If voltage is less than 4 volts on models with EVP, PFE or DPFE sensor, reconnect TP sensor and go to next step. If voltage is less than 4 volts on all other models, reconnect TP sensor and go to step 8).
6. Check For Shorted EVP PFE Or DPFE Sensor Turn ignition off. Disconnect EVP PFE or DPFE sensor. Turn ignition on. Measure voltage between test pins No. 26 and 46. If voltage is 4 volts or more, replace EVP PFE or DPFE sensor. Remove breakout box, reconnect components and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If voltage is less than 4 volts, reconnect EVP PFE or DPFE sensor and go to step 8).
7. Check For Shorted Power Steering Pressure (PSP) Sensor Disconnect PSP sensor connector. Turn ignition on. Measure voltage between test pins No. 26 and 46 at breakout box. If voltage is less than 4 volts, reconnect PSP sensor and go to next step. If voltage is 4 volts or more, replace PSP sensor. Remove breakout box, reconnect components and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
8. Check For Shorted MAP/BARO Sensor On models not equipped with a MAP/BARO sensor, go to next step. On all other vehicles, turn ignition off. Ensure PCM is connected to breakout box. Disconnect MAP/BARO sensor. Turn ignition on. Measure voltage between test pins No. 26 and 46. If voltage is 4 volts or more, replace MAP/BARO sensor. Remove breakout box, reconnect components and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If voltage is less than 4 volts, reconnect MAP/BARO sensor and to next step.
9. Check VREF Circuit For Short To Ground Turn ignition off. Disconnect PCM. Disconnect TP sensor, MAP/BARO sensor and EVP/PFE/DPFE sensor (if equipped). Measure resistance between test pin No. 26 and test pins No. 20, 40, 46 and 60. If any resistance is less than 1000 ohms, repair short to ground. Remove breakout box, reconnect components and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If readings are 1000 ohms or more, replace PCM. Remove breakout box, reconnect components and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .

Perform this test only when directed by QUICK TEST. Ambient air temperature must be at least 50°F (10°C) to receive valid input from IAT sensor. Engine coolant temperature must be more than 50°F (10°C) to pass KOEO SELF-TEST and more than 180°F (82°C) to pass KOER SELF-TEST. Voltage values in this test are based on a 5-volt VREF signal. Values may vary up to 15 percent due to sensor and VREF variations.

This circuit test is intended to diagnose the following components and circuits

1. Intake Air Temperature (IAT) sensor.
2. Engine Coolant Temperature (ECT) sensor.
3. Wiring harness circuits (IAT, ECT and SIG RTN).
4. Powertrain Control Module (PCM).

To prevent replacing good components, ensure the following non-EEC areas or components are not cause of problem

Scheme 32

1. Coolant level low.
2. Cooling system, water pump or fan.
3. Engine operating temperature.
4. Engine oil level low.
5. Thermostat.
6. Air cleaner duct.
7. Ambient temperature. (Scheme 32): Temperature Sensor Circuits & Connector Terminals TEST PIN WIRE COLOR IDENTIFICATION Application Wire Color TEST PIN NO. 7 (ECT) Light Green/Red TEST PIN NO. 25 (IAT) Gray TEST PIN NO. 46 (SIG RTN) Gray/Red

1. 1) Code 114 Or 116 Code 114 (IAT) or 116 (ECT) indicates corresponding sensor is out of self-test range. Correct range for measurement is 0.3-3.7 volts. Check for following possible causes: Ambient temperature less than 50°F (10°C). Low coolant level. Faulty harness connector. Faulty sensor. Start engine and run until engine is at normal operating temperature. If vehicle cannot be started, go to step 3). If vehicle starts and stalls, go to «CIRCUIT TEST S»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If vehicle starts, ensure upper radiator hose is hot and pressurized. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If Code 114 or 116 is present, go to next step. If none of these codes are present, service other codes as necessary.
2. 2) Check VREF Circuit Voltage At TP Sensor Turn ignition off. Disconnect Throttle Position (TP) sensor. With ignition on and engine off, measure voltage at TP sensor wiring harness connector between VREF and SIG RTN. If voltage is 4-6 volts, reconnect TP sensor and go to next step. If voltage is not 4-6 volts, go to «CIRCUIT TEST C»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
3. 3) Check Temperature Sensor Resistance Turn ignition off. Disconnect suspect sensor. Measure resistance between sensor terminals. See «ACT & ECT SENSOR SPECIFICATIONS»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) table. If resistance is not within specification, replace suspected sensor and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If resistance is within specification, perform following step as applicable: For diagnosing vehicles with ECT sensor and a no-start condition, DO NOT service Code 116 at this time. Go to CIRCUIT TEST AA for models equipped with Distributor Ignition, or «CIRCUIT TEST AC»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__circuit-test-ac-no-start-ei) for models equipped with High Data Rate Electronic Ignition system (formally Electronic Distributorless Ignition - EDIS). For diagnosing vehicles with ECT sensor, without a no-start condition, go to next step.
4. 4) Check Temperature Sensor Resistance Warm engine to normal operating temperature. Turn ignition off. Disconnect suspect sensor. Run engine at 2000 RPM for 2 minutes. Measure resistance between sensor terminals. See «ACT & ECT SENSOR SPECIFICATIONS»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) table. If resistance is within specification, replace PCM and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If sensor is not within specification, replace sensor and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . ACT & ECT SENSOR SPECIFICATIONS Temperature °F (°C) (1) Volts (1) Ohms 50 (10) 3.51 58,750 68 (20) 3.07 27,300 86 (30) 2.60 24,270 104 (40) 2.13 16,150 122 (50) 1.70 10,970 140 (60) 1.33 7700 158 (70) 1.02 5370 176 (80) 0.78 3840 194 (90) 0.60 2800 212 (100) 0.46 2070 (1) Values may vary by 15 percent. NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 4) to step 10). No test procedures have been omitted.
5. 10) Code 118 Or 113: Induce Opposite Code (Code 112 Or 117) Code 118 (ECT) or 113 (IAT) indicate corresponding sensor signal is more than self-test maximum. Maximum signal voltage for ECT and IAT sensor is 4.6 volts. Possible causes for excess voltage signals are: Open circuit in wiring harness (IAT or ECT). Faulty connection. Faulty sensor. Faulty PCM. Turn ignition off. Disconnect suspect temperature sensor. Connect a jumper wire between SIG RTN terminal at sensor and SIG RTN terminal at sensor wiring harness connector. Repeat «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) . If Code 112 or 117 is displayed, replace suspect sensor, remove jumper wire, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If Code 112 or 117 is not displayed, remove jumper wire and go to next step.
6. 11) Check Continuity Of Sensor Signal & SIG RTN Circuits Turn ignition off. Ensure suspect temperature sensor is disconnected. Disconnect PCM 60-pin connector. Check for damaged wiring, and repair as necessary. Install Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pin No. 7 (ECT sensor) or test pin No. 25 (IAT sensor) at breakout box and SIG RTN terminal at sensor wiring harness connector. Also, measure resistance between test pin No. 46 and SIG RTN circuit at sensor wiring harness connector. If both readings are less than 5 ohms, replace PCM. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If either reading is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
7. 12) Check If Sensor Signal Is Shorted To VREF Circuit Turn ignition off. Ensure suspect temperature sensor is disconnected. Disconnect PCM 60-pin connector. Check for damaged wiring, and repair as necessary. Install Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pin No. 7 (ECT sensor) or test pin No. 25 (IAT sensor) at breakout box and VREF terminal (No. 26) at breakout box. If resistance is more than 10,000 ohms, replace PCM. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If resistance is 10,000 ohms or less, repair short in VREF circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 12) to step 20). No test procedures have been omitted.
8. 20) Code 112 or 117: Induce Opposite Code (113 or 118) Code 117 (ECT) or 112 (IAT) indicates sensor signal is less than self-test minimum. Minimum signal for IAT and ECT sensor is 0.2 volt. Possible causes for this fault are: Circuit grounded in wiring harness. Faulty sensor. Faulty PCM. Faulty connection. Turn ignition off. Disconnect wiring harness connector from suspect sensor. Check for damaged wiring, and repair as necessary. Repeat «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) . If Code 113 or 118 is displayed, replace sensor and reconnect harness. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If Codes 113 or 118 is not displayed, go to next step.
9. 21) Check VREF Circuit Voltage At TP Sensor Turn ignition off. Disconnect wiring harness connector from suspect sensor. Disconnect TP sensor. Turn ignition on. Measure voltage between VREF and SIG RTN at TP sensor wiring harness connector. If voltage is not 4-6 volts, go to «CIRCUIT TEST C»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If voltage is 4-6 volts, connect TP sensor and go to next step.
10. 22) Check Temperature Sensor Signal For Shorts To Ground Turn ignition off. Disconnect suspect sensor. Disconnect PCM 60-pin connector. Check for damaged wiring, and repair as necessary. Install Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pin No. 7 (ECT sensor) or 25 (IAT sensor) and test pins No. 40, 46 and 60 at breakout box. If any reading is less than 10,000 ohms, repair short circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If all readings are 10,000 ohms or more, replace PCM. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 22) to step 90). No test procedures have been omitted.
11. 90) Continuous Memory Code 112, 113, 117 Or 118: Check Sensor A Continuous Memory Code 113 or 118 indicates sensor signal is more than self-test maximum of 4.6 volts. Code is set during normal driving conditions. Continuous Memory Code 112 or 117 indicates sensor signal is less than self-test minimum of 0.2 volt. Code is set during normal driving conditions. Possible causes for these faults are: Faulty sensor. Open or grounded circuit in harness. Faulty PCM. SENSOR CODES Sensor Continuous Memory Code IAT 112 Or 113 ECT 117 Or 118 Enter KOEO wiggle test mode. See «CONTINUOUS MONITOR MODE (WIGGLE TEST)»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__continuous-monitor-mode-wiggle-test) under QUICK TEST. Observe analog voltmeter or scan tester for indication of fault while tapping sensor lightly and wiggling sensor connector. If fault is indicated, disconnect and inspect connector and terminals. If connector and terminals are okay, replace sensor, clear continuous memory and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If fault is not indicated, go to next step.
12. 91) Check EEC-IV Wiring Harness While in «CONTINUOUS MONITOR MODE (WIGGLE TEST)»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__continuous-monitor-mode-wiggle-test) , observe analog voltmeter or scan tester while wiggling and bending wiring harness, a small section at a time, from sensor to cowl. Also, check harness from cowl to PCM. If fault is indicated, isolate fault and repair as necessary. Clear continuous memory, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If no fault is found, go to next step.
13. 92) Inspect PCM & Wiring Harness Connectors Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. If connectors and terminals are damaged, repair as necessary and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If connectors and terminals are okay and fault cannot be duplicated at this time, see INTERMITTENTS in the «TESTS W/O CODES»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wo-codes) article. NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 92) to step 100). No test procedures have been omitted.
14. 100) Continuous Memory Code 338 A Continuous Memory Code 338 indicates cooling system has not reached normal operating temperature. Possible causes for this fault are: Thermostat stuck open. Coolant outlet gasket leak. Water pump gasket leak. Heater hose leak. Repair cooling system as necessary. Clear continuous memory, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
15. 101) Continuous Memory Code 339 A Continuous Memory Code 339 indicates cooling system has overheated. Possible causes for this fault are: Coolant level low. Thermostat stuck closed. Coolant system clogged. Water pump damaged or worn. Radiator cap damaged or worn. Cooling fan damaged or worn. Repair cooling system as necessary. Clear continuous memory, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .

Perform this test when instructed by QUICK TEST or if directed by other test procedures.

To prevent replacement of good components, be aware the following non-EEC related areas may be cause of problem

1. Damaged EGR valve.
2. Damaged EGR transducer.
3. Stuck throttle plate.
4. Exhaust system restriction.
5. Damaged canister, reservoir and/or vacuum hoses.

This CIRCUIT TEST is intended to diagnose the following

Scheme 33

1. EGRT sensor.
2. EGRT and SIG RTN wiring harness circuits.
3. Powertrain Control Module (PCM). (Scheme 33): EGR Temperature (EGRT) Sensor Circuits/Connector Terminals

1. 1) Continuous Memory Code 327: Verification Code 327 indicates that at least once within previous 40 warm-up cycles, EGRT sensor signal was less than self-test minimum. Possible causes for this fault are: Faulty EGRT sensor. Open or grounded wiring harness. Faulty PCM. Turn ignition off. Clear codes from PCM memory. Start engine, and let it run for at least 2 minutes. Repeat «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) . If Code 327 is not displayed, go to step 90). If Code 327 is displayed, go to next step.
2. 2) Induce Opposite Code Clear codes from PCM memory. Disconnect EGRT sensor. Start engine, and let it run for at least 2 minutes. Repeat «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) . If Code 337 is not displayed, go to next step. If Code 337 is displayed, replace EGRT sensor. Clear continuous memory, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
3. 3) Check EGRT Circuit For Short To Ground Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Disconnect EGRT sensor wiring harness connector. Measure resistance between test pin No. 43 and pins No. 40, 46 and 60 at breakout box. If all readings are 10,000 ohms or more, replace PCM. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If any reading is less than 10,000 ohms, repair short circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 3) to step 5). No test procedures have been omitted.
4. 5) Continuous Memory Code 337: Verification Code 337 indicates that at least once within previous 40 warm-up cycles, EGRT sensor signal was more than self-test maximum. Possible causes for this fault are: Faulty EGRT sensor. Open wiring harness circuit. Faulty PCM. Clear codes from PCM memory. Start engine, and let it run for at least 2 minutes. Repeat «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) . If Code 337 is not displayed, go to step 90). If Code 337 is displayed, go to next step.
5. 6) Check EGRT Circuit For Short To Power Turn ignition off. Disconnect EGRT sensor. Turn ignition on. Measure voltage between EGRT terminal at EGRT sensor wiring harness connector and negative battery terminal. If voltage is 1.0 volt or more, repair short and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If voltage is less than 1.0 volt, go to next step.
6. 7) Induce Opposite Code Clear codes from PCM memory. Connect jumper wire between EGRT terminal and SIG RTN terminal at EGRT sensor wiring harness connector. Start engine, and let it run for at least 2 minutes. Repeat «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) . If Code 327 is displayed, replace EGRT sensor. Clear continuous memory, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If Code 327 is not displayed, go to next step.
7. 8) Check Continuity Of Circuits Turn ignition off. Disconnect PCM 60-pin connector. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM and EGRT sensor disconnected. Measure resistance between EGRT terminal at EGRT wiring harness connector and test pin No. 43 at breakout box. Also, measure resistance between SIG RTN terminal at EGRT wiring harness connector and test pin No. 46 at breakout box. If either reading is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If both readings are less than 5 ohms, replace PCM. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 8) to step 10). No test procedures have been omitted.
8. 10) Continuous Memory Code 326 Code 326 indicates that within previous 40 warm-up cycles, PCM detected EGR flow at idle. Possible causes for this fault are: EGR valve stuck open. Faulty EGRT sensor. Open or shorted wiring harness circuit. Clear codes from PCM memory. Start engine, and let it run for at least 2 minutes. If engine idles rough or stalls, clean or replace EGR valve. If engine does not stall or idle rough, go to next step.
9. 11) Verify Condition Repeat «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) . If Continuous Memory Code 326 is not present, go to step 90). If Continuous Memory Code 326 is present, go to next step.
10. 12) Check Continuity Of Harness Circuits Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Disconnect EGRT sensor connector. Measure resistance between EGRT terminal at EGRT wiring harness connector and test pin No. 43 at breakout box. Also, measure resistance between SIG RTN terminal at EGRT wiring harness connector and test pin No. 46 at breakout box. If either resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If either resistance is less than 5 ohms, replace EGRT sensor. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 12) to step 20). No test procedures have been omitted.
11. 20) Continuous Memory Code 332 Code 332 indicates that within previous 80 warm-up cycles, PCM did not detect EGR flow at part throttle. Possible causes for this fault are: Damaged or plugged vacuum line. EGR valve stuck closed. Damaged EGR pressure transducer. Damaged or plugged exhaust tube. Faulty EGRT sensor. Open or shorted wiring harness circuit. Turn ignition off. Disconnect vacuum hose at EGR valve. Connect vacuum pump to EGR valve. Apply 10 in. Hg to EGR valve. If vacuum is not held, repair or replace EGR valve. If vacuum is held, go to next step.
12. 21) Release vacuum from EGR valve. Clear codes from PCM memory. Start engine. Apply 10 in. Hg to EGR valve, and hold 2 minutes. If engine idles rough or stalls, go to next step. If engine does not idle rough or stall, clean or replace EGR valve.
13. 22) Repeat «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) . If Continuous Memory Code 326 is present, clean or repair EGR system as necessary. See EMISSION SYSTEMS & SUB-SYSTEMS in the «SYSTEM/COMPONENT TESTS»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-46l) article. If Continuous Memory Code 326 is not present, replace EGRT sensor and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 22) to step 90). No test procedures have been omitted.
14. 90) Check EEC-IV Wiring Harness Enter wiggle test. See «CONTINUOUS MONITOR MODE (WIGGLE TEST)»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__continuous-monitor-mode-wiggle-test) under QUICK TEST. Bend, wiggle and shake small sections of EEC-IV harness from TP sensor wiring harness connector to firewall and from firewall to PCM while observing analog voltmeter or scan tester. If fault is indicated, isolate fault in wiring and repair as necessary. Clear codes, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If no fault is indicated, go to next step.
15. 91) Check PCM & Harness Connectors Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Clear codes from PCM memory, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If connectors and terminals are okay, fault cannot be duplicated at this time. Testing is complete.

Perform this test when directed by QUICK TEST. This CIRCUIT TEST is intended to diagnose the following

1. MAF sensor.
2. Wiring harness circuits (VPWR, PWR GND, MAF and MAF RTN).
3. Powertrain Control Module (PCM).

To prevent replacement of good components, be aware the following non-EEC related areas may be cause of problem

1. Air cleaner element.
2. Inlet air duct.
3. Throttle body.

Code 159, retrieved during KOEO SELF-TEST, indicates voltage exceeded .7-volt test range. Code 159, retrieved during KOER SELF-TEST, indicates voltage is not within 0.2-1.5 volts operating range.

Mass Airflow (MAF) Sensor Wiring Harness Extension. Scheme 34

Mass Airflow (MAF) Sensor Circuits/Connector Terminals. Scheme 35

TEST PIN WIRE COLOR IDENTIFICATION

MAF SIGNAL VOLTAGE (1)

Note. Code 159 may be caused by use of a garage exhaust ventilation system. Ensure vehicle is vented to outside atmosphere before repeating QUICK TEST .

1. 1) Code 159: Check VPWR Circuit Voltage Code 159 indicates that MAF sensor was out of range during KOEO or KOER SELF-TEST. Possible causes for this fault are: Air leak before or after MAF sensor. Faulty MAF sensor. Faulty IAC solenoid. Open or grounded wiring harness. Faulty PCM. Turn ignition off. Disconnect MAF sensor connector. Set DVOM on 20-volt scale. Turn ignition on. Measure voltage between VPWR terminal at MAF sensor wiring harness connector and negative battery terminal. If voltage is less than 10.5 volts, repair open in VPWR circuit and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If voltage is 10.5 volts or more, go to next step.
2. 2) Check MAF Sensor Ground Turn ignition on. With MAF sensor disconnected, measure voltage between VPWR terminal and PWR GND terminal at MAF sensor connector. If voltage is less than 10.5 volts, repair open PWR GND circuit. Connect MAF sensor, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If voltage is 10.5 volts or more, go to step 13). NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 2) to step 10). No test procedures have been omitted.
3. 10) Continuous Memory Code 157: Check For Intermittent Sensor Failure Continuous Memory Code 157 indicates MAF signal was less than 0.4 volt sometime during last 40 warm-up cycles. Possible causes for this fault are: Open MAF circuit. MAF circuit shorted to ground. Faulty MAF sensor. MAF sensor disconnected. Clear continuous memory. Start engine and allow to idle for 5-10 minutes. Increase engine speed to 1500 RPM for 5 seconds. Perform «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) . If Code 157 is present, go to step 13). If Code 157 is not present, go to next step.
4. 11) Monitor MAF Circuit Under Simulated Road Shock Turn ignition off. Disconnect and inspect 60-pin connector at PCM. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM connected. Connect DVOM between MAF test pin and MAF RTN test pin. See appropriate table at beginning of this CIRCUIT TEST. DVOM should read about 0.4 volt. Start engine and allow to idle. Lightly tap on MAF sensor and wiggle wiring harness to simulate road conditions. If sudden change in DVOM reading occurs, fault is indicated. If fault is indicated, replace MAF sensor and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If no fault is indicated, leave DVOM connected and go to next step.
5. 2) Check Wiring Harness For Open Or Short Circuit Turn ignition on. Shake and bend small sections of wiring harness starting at MAF sensor and working toward dash panel. Shake and bend small sections of wiring harness starting at dash panel and working toward PCM. If fault is indicated, isolate and repair as necessary. If fault is not indicated, problem is intermittent and cannot be duplicated at this time.
6. 13) Codes 129 Or 157: Check For Air Leak At MAF Sensor Check for broken or loose air outlet tube clamps at throttle body and air cleaner assembly. Repair or replace as necessary. If no faults are found, go to next step.
7. 14) Check Continuity Of MAF & VPWR Circuit Turn ignition off. Disconnect MAF sensor and PCM wiring harness connector. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between MAF terminal of MAF sensor wiring harness connector and test pins No. 37 and 57. Measure resistance between MAF terminal of MAF sensor wiring harness connector and test pin No. 50. If resistance is more than 5 ohms, repair open circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If resistance is 5 ohms or more, go to next step.
8. 15) Check MAF Signal For Short To Ground Turn ignition off. Ensure MAF sensor and PCM wiring harness are disconnected. Measure resistance between test pin No. 50 and test pins No. 9, 40 and 60. If any reading is less than 10,000 ohms, repair short circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If all readings are 10,000 ohms or more, go to next step.
9. 16) Turn ignition off. Ensure MAF sensor and PCM wiring harness connectors are disconnected. Measure resistance between PWR GND terminal at MAF sensor wiring harness connector and negative battery terminal. If resistance is 10 ohms or more, repair open PWR GND circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If resistance is less than 10 ohms, go to next step.
10. 17) Check Continuity Of MAF RTN Circuit Ensure ignition is turned off. Measure resistance between MAF RTN terminal of MAF sensor wiring harness connector and test pin No. 9 at breakout box. If resistance is more than 5 ohms, repair open circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If resistance is 5 ohms or more, go to next step.
11. 18) Check MAF Circuit For Short To Ground Turn ignition off. Ensure MAF sensor is disconnected. Connect PCM to breakout box. Measure resistance between test pin No. 50 and test pins No. 9, 40 and 60. If any reading is less than 10,000 ohms, replace PCM. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If all readings are 10,000 ohms or more, go to next step.
12. 19) Check MAF Circuit Output Turn ignition off. Connect MAF sensor wiring harness connector. Start engine. Measure resistance between test pin No. 50 and negative battery terminal. If voltage is .36-1.50 volts, go to next step. If voltage is not .36-1.50 volts, replace MAF sensor. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
13. 20) With engine running, measure resistance between test pin No. 9 and test pin No. 50. If voltage is .36-1.50 volts, go to next step. If voltage is not .36-1.50 volts, replace MAF sensor. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . NOTE: Code 158 may be caused by foreign material blocking MAF sensor screen creating an airflow restriction. If contaminates are found on screen, check air filter installation in air cleaner tray, and proper sealing or air cleaner/tube before proceeding.
14. 21) Check For Other Trouble Codes Check if Code 411 or 412 is also present with Code 129 or 159. If Code 411 is also present , go to step 15) in «CIRCUIT TEST KE»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If Code 411 is also present, go to step 1) in «CIRCUIT TEST KE»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If no other codes are present, replace PCM. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
15. 22) Code 158: Repeat «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) Turn ignition off. Disconnect MAF sensor wiring harness connector. Start engine, and allow it to idle for one 5-10 minutes. Raise engine speed to 1500 RPM for 10 seconds. Turn ignition off. Repeat «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) . If Code 157 is present, replace MAF sensor and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If Code 157 is not present, go to next step.
16. 23) Check MAF Circuit For Short To VPWR Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Measure resistance between MAF and VPWR terminals at MAF sensor wiring harness connector. If resistance is 10,000 ohms or more, replace PCM. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If resistance is less than 10,000 ohms, repair short circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .

Perform this test only when directed by QUICK TEST. This circuit test is intended to diagnose the following components and circuits

Scheme 36

Scheme 37

1. EGRP sensor.
2. Wiring harness circuits (EGRP, SIG RTN, VREF, EGRV, EGRA and VPWR).
3. Powertrain Control Module (PCM).
4. Vacuum lines (EGRV, EGRA and EGR. (Scheme 36): Identifying EGRP Sensor Connector Terminals (Scheme 37): Identifying EGRV & EGRA Solenoid Connector Terminals

1. 1) Code 327: Attempt To Generate Code 337 Code 327 indicates EGR Position (EGRP) sensor signal is less than self-test minimum. Possible causes for this fault are: Faulty EGRP sensor/EGR valve assembly. Open sensor VREF or SIG RTN circuits. Open sensor VREF circuit. Short to ground in sensor EGRP circuit. Faulty Powertrain Control Module (PCM). Turn ignition off. Disconnect EGRP sensor connector. Connect jumper wire between terminals VREF and EGRP of EGRP sensor wiring harness connector. Repeat «KOER SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) and «KOER SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If Code 337 is displayed, replace EGRP sensor/EGR valve assembly. Remove jumper wire, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . Disregard any other codes that are set at this time. If Code 337 is not displayed, remove jumper wire, and go to next step.
2. 2) Check EGRP VREF Voltage Turn ignition on. Ensure EGRP sensor is disconnected. Measure voltage between VREF and SIG RTN terminals at EGRP sensor connector. If voltage is 4-6 volts, go to next step. If voltage is not 4-6 volts, go to «CIRCUIT TEST C»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
3. 3) Check EGRP Sensor SIG RTN Circuit Continuity Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between SIG RTN terminal of EGRP sensor connector and test pin No. 46 at breakout box. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
4. 4) Check For Short To Ground In EGRP SIG RTN Circuit Measure resistance between test pin No. 27 and test pins No. 40, 46 and 60 at breakout box. If all readings are more than 10,000 ohms, replace PCM. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If any reading is 10,000 ohms or less, repair short to ground. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 4) to step 10). No test procedures have been omitted.
5. 10) Code 337: Attempt To Generate Code 327 Code 337 indicates EGR Position (EGRP) sensor signal is more than self-test minimum. Possible causes for this fault are: Open or short in EGRP circuit. Faulty EGRP sensor/EGR valve assembly. Faulty EGR Vacuum (EGRV) solenoid valve. Faulty Powertrain Control Module (PCM). Improper EGR valve vacuum hose routing. Turn ignition off. Disconnect EGRP sensor connector. Connect jumper wire between EGRP and SIG RTN terminals of EGRP sensor wiring harness connector. Repeat «KOER SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) and «KOER SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If Code 327 is displayed, remove jumper wire, and go to step 13). Disregard any other codes that are set at this time. If Code 327 is not displayed, remove jumper wire, and go to next step.
6. 11) Check EGRP Circuit Continuity Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair connector as necessary. Ensure EGRP sensor is disconnected. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between EGRP terminal at EGRP sensor connector and test pin No. 27 at breakout box. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
7. 12) Check For Short To Power In EGRP Circuit Measure resistance between test pin No. 27 and test pins No. 26, 37 and 57 at breakout box. If all readings are more than 10,000 ohms, replace PCM. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If any reading is less than 10,000 ohms, repair short circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
8. 13) Check Vacuum At EGRV Solenoid Valve Turn ignition off. Disconnect EGRV solenoid vacuum line at EGRV solenoid output port. Install vacuum gauge at output port of EGRV solenoid. Start engine and allow it to idle. Observe vacuum gauge. If vacuum is present, replace EGRV solenoid. Remove vacuum gauge. Reconnect all components and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If vacuum is not present, check EGR valve vacuum hose routing. Repair as necessary. If hose routing is okay, replace EGRP sensor/EGR valve assembly. Remove vacuum gauge. Reconnect all components and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 13) to step 20). No test procedures have been omitted.
9. 20) Code 571 & 572: Check EGRA/EGRV Solenoid Resistance Code 571 indicates failure in EGRA solenoid circuit. Code 572 indicates failure in EGRV solenoid circuit. Possible causes for this fault are: Open or short in wiring harness. Faulty EGRA/EGRV solenoid. Faulty Powertrain Control Module (PCM). Turn ignition off. Disconnect EGRA (Code 571) or EGRV (Code 572) solenoid connector. Measure resistance between solenoid connector terminals. If resistance is 30-70 ohms, go to next step. If resistance is not 30-70 ohms, replace solenoid, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
10. 21) Check Solenoid VPWR Circuit Turn ignition on. Ensure solenoid to be tested is disconnected. Measure voltage between negative battery terminal and VPWR terminal at solenoid connector. If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, repair open circuit. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
11. 22) Check Solenoid Circuit Continuity Turn ignition off. Ensure solenoid to be tested is disconnected. Disconnect PCM 60-pin connector. Inspect for damage, and repair if necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. If testing EGRA solenoid, measure resistance between test pin No. 12 at breakout box and EGRA terminal at solenoid connector. If testing EGRV solenoid, measure resistance between test pin No. 33 at breakout box and EGRV terminal at solenoid connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
12. 23) Check For Solenoid Circuit Short If testing EGRA solenoid, measure resistance between test pin No. 12 and test pins No. 37, 40, 57 and 60 at breakout box. If testing EGRV solenoid, measure resistance between test pin No. 33 and test pins No. 37, 40, 57 and 60 at breakout box. If all readings are more than 10,000 ohms, replace PCM. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If any reading is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 23) to step 30). No test procedures have been omitted.
13. 30) Code 332: Check Vacuum To EGR Valve Code 332 indicates EGRP sensor input did not change after PCM commanded EGR valve to open. Possible causes for this fault are: Faulty vacuum lines. Faulty EGRP/sensor/EGR valve assembly. Faulty EGRA solenoid. Faulty EGRV solenoid. Turn ignition off. Disconnect EGR vacuum hose at EGR valve, and connect vacuum gauge to disconnected vacuum hose. Repeat «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) , while observing vacuum gauge. If vacuum is less than 1.0 in. Hg throughout «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) , go to next step. If vacuum is 1.0 in. Hg or more throughout KOEO SELF-TEST, replace EGRP sensor/EGR valve. Reconnect all components and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
14. 31) Check EGR Vacuum Hose Ensure EGR valve vacuum hose is disconnected. Insect vacuum hose between EGR valve and EGRV/EGRA solenoids. Replace hose as necessary. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If vacuum hose is okay, reconnect vacuum hose, and go to next step.
15. 32) Check Vacuum To EGRV Solenoid Turn ignition off. Disconnect vacuum hose from EGRV solenoid input port. Install vacuum gauge to disconnected hose. Start engine and allow it to idle. If vacuum is more than 10 in. Hg, remove vacuum gauge. Reconnect vacuum hose, and go to next step. If vacuum is 10 in. Hg or less, check vacuum hose to EGRV solenoid. Replace hose as necessary. If vacuum hose is okay, check vacuum source for solenoid. Repair as necessary. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
16. 33) Check EGRV Solenoid Valve Turn ignition off. Disconnect vacuum hose from EGRV solenoid output port. Install vacuum gauge to output port of EGRV solenoid. Repeat KOEO SELF-TEST and observe vacuum gauge. If vacuum signal decreases then increases, remove vacuum gauge, and go to next step. If vacuum signal does not decrease then increase, replace EGRV solenoid. Remove vacuum gauge. Reconnect all components and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
17. 34) Check EGRV Solenoid Output Port Vacuum Hose Disconnect vacuum hose from EGRV solenoid output port. Inspect vacuum hose for obstructions, cracks and kinks. Replace vacuum hose as necessary, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If vacuum hose is okay, reconnect vacuum hose and go to next step.
18. 35) Check EGRA Solenoid Vacuum Hose Disconnect EGRA vacuum hose. Inspect vacuum hose for obstructions, cracks and kinks. Replace vacuum hose as necessary, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If vacuum hose is okay, replace EGRA solenoid. Reconnect vacuum hose, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 35) to step 90). No test procedures have been omitted.
19. 90) Continuous Memory Code 327 Or 337: Check for Intermittent Continuous Memory Code 327 indicates EGRP sensor input to PCM was below minimum acceptable voltage sometime during vehicle operation. Continuous Memory Code 337 indicates EGRP sensor input to PCM was more than the maximum acceptable voltage sometime during vehicle operation. Possible causes for this fault are: Faulty EGRP/sensor/EGR valve assembly. Intermittent open in EGRP sensor SIG RTN circuit. Intermittent open in EGRP circuit. Intermittent open in EGRP sensor VREF circuit. Intermittent short to power in EGRP circuit. Enter «CONTINUOUS MONITOR MODE (WIGGLE TEST)»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__continuous-monitor-mode-wiggle-test) . Observe test equipment and perform the following: Lightly tap on EGRP sensor (to simulate road shock). Wiggle sensor wiring harness connector. If a fault is indicated, inspect EGRP sensor connector and terminals. Repair as necessary. If connector and terminals are okay, replace EGRP sensor/EGR valve assembly. Clear codes, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If a fault is not indicated, go to next step.
20. 91) Check For Intermittent Harness Damage: Check For Intermittent Sensor Damage While still in «CONTINUOUS MONITOR MODE (WIGGLE TEST)»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__continuous-monitor-mode-wiggle-test) , observe test equipment and perform the following. Shake and bend small sections of wiring harness starting at EGRP sensor and working toward dash panel. Also, shake and bend small sections of wiring harness starting at dash panel and working toward PCM. If a fault is indicated, isolate fault and repair as necessary. Clear codes and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If a fault is not indicated, go to next step.
21. 92) Check PCM Connector Turn ignition off. Disconnect PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Clear codes and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If connector and wiring are okay, fault cannot be duplicated at this time. Testing is complete. NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 92) to step 100). No test procedures have been omitted.
22. 100) Continuous Memory Code 332: Check EGR Valve Function Continuous Memory Code 332 indicates EGR valve did not open when engine load and requested conditions had been met sometime during vehicle operation. Possible causes for this fault are: Faulty EGRP/sensor/EGR valve assembly. Faulty EGR valve vacuum hose. Faulty EGRV or EGRA solenoid vacuum lines. Turn ignition off. Disconnect and plug EGR valve vacuum line at EGR valve. Connect vacuum pump to EGR valve. Apply 10 in. Hg to EGR valve. Observe EGR valve and release vacuum. If EGR valve functions properly, remove vacuum pump. Unplug vacuum hose, and go to next step. If EGR valve does not function properly, remove EGRP sensor/EGR valve assembly. Inspect EGR valve for blockage, binding, contamination and leakage. Repair or replace EGR valve assembly as necessary. Clear codes and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
23. 101) Check EGR Valve Vacuum Hose Disconnect EGR vacuum hose at vacuum source and EGR valve. Inspect vacuum hose for obstructions, cracks and kinks. Replace vacuum hose as necessary. Clear codes and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If vacuum hose is okay, reconnect vacuum hose and go to next step.
24. 102) Check EGRA & EGRV Solenoid Vacuum Hoses Disconnect solenoid vacuum hose to be checked. Inspect vacuum hose for obstructions, cracks and kinks. Replace vacuum hose as necessary. Clear codes and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If vacuum hose is okay, reconnect vacuum hoses and go to next step.
25. 103) Check EGRV/EGRA Solenoids & Circuits For Intermittent Fault Turn ignition off. Disconnect vacuum hose at EGR valve and connect vacuum pump to disconnected hose. Start engine and allow it to idle. Observe vacuum pump for increased vacuum while performing the following: Lightly tap on EGRV and EGRA solenoids (to simulate road shock). Wiggle EGRV and EGRA solenoid wiring harness connectors. If vacuum reading increased, isolate fault and repair as necessary. Clear codes and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If vacuum reading did not increase, fault cannot be duplicated at this time. Testing is complete.

Perform this test when directed by QUICK TEST. Barometric pressure sensor output is digital and must be measured using an oscilloscope or MAP/BARO tester. To prevent replacement of good components, be aware the following non-EEC related areas may be cause of problem

1. Unusually high or low atmospheric barometric pressure.
2. Kinked or blocked vacuum lines.
3. Engine mechanical condition (valves, vacuum leaks, timing, EGR valve, etc.).

This test is intended to diagnose the following

Scheme 38

1. MAP/BARO sensor.
2. Wiring harness circuits (VREF, MAP/BARO SIG and SIG RTN).
3. MAP vacuum line.
4. Powertrain Control Module (PCM). (Scheme 38): MAP/BARO Sensor Circuits, Connector Terminals & Tester Hookup TEST PIN WIRE COLOR IDENTIFICATION Application Wire Color TEST PIN NO. 26 (VREF) Brown/White TEST PIN NO. 45 (MAP/BARO SIG) Dark Blue/Light Green TEST PIN NO. 46 (SIG RTN) Gray/Red MAP SENSOR SPECIFICATIONS Manifold Vacuum: In. Hg Frequency: Hz 0 159 3 150 6 141 9 133 12 125 15 117 18 109 21 102 24 95 27 88 30 80 MAP/BARO SENSOR SPECIFICATIONS Barometric Pressure: In. Hg Frequency: Hz 17.1 122.4 18.3 125.5 19.5 128.7 20.7 131.9 21.8 135.1 23.0 138.3 24.2 141.8 25.4 145.4 26.6 148.9 27.7 152.5 28.9 156.1 30.1 159.6 31.0 162.4

1. 1) Code 126: Check Power To MAP/BARO Sensor Code 126 indicates MAP/BARO sensor is out of self-test voltage range (1.4-1.6 volts). Following are possible causes of this code: Vacuum trapped at MAP/BARO sensor. High atmospheric pressure. MAP/BARO signal circuit open between sensor and PCM. MAP/BARO signal circuit shorted to VREF, SIG RTN or GND. VREF circuit open at sensor. SIG RTN circuit open at sensor. Faulty MAP/BARO sensor. Faulty PCM. Turn ignition off. Disconnect MAP/BARO sensor from wiring harness. Connect MAP/BARO tester between wiring harness and MAP/BARO sensor. Connect banana plugs of tester into DVOM. Set DVOM on 20-volt scale. Turn ignition on. If Red light or no light is on, VREF is out of range. Go to next step. If Green light is on, VREF is okay. Go to step 3).
2. 2) Check Power At Sensor Wiring Harness Connector Disconnect MAP/BARO sensor. Turn ignition on. If tester Green light is on, replace MAP/BARO sensor and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If Green light is off, remove MAP/BARO tester. Connect MAP/BARO sensor, and go to «CIRCUIT TEST C»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
3. 3) Check MAP/BARO Sensor Output With MAP/BARO tester connected and ignition on, measure sensor output voltage. If output voltage is within range for altitude in which vehicle is being tested, remove MAP/BARO tester and go to next step. See «MAP SENSOR VOLTAGE OUTPUT»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) table. If output voltage is not within range, remove MAP/BARO tester and go to step 5). MAP SENSOR VOLTAGE OUTPUT Elevation (Feet) Volts 0 1.59 1000 1.56 2000 1.53 3000 1.50 4000 1.47 5000 1.44 6000 1.41 7000 1.39
4. 4) Check MAP/BARO SIG Circuit Continuity Turn ignition off. Disconnect MAP/BARO sensor wiring harness connector. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair connector as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between MAP/BARO SIG terminal at sensor wiring harness connector and test pin No. 45. If resistance is less than 5 ohms, replace PCM and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If resistance is 5 ohms or more, repair open MAP/BARO SIG circuit and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
5. 5) Check MAP/BARO SIG Circuit For Short To VREF, SIG RTN & Ground Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Disconnect wiring harness at MAP/BARO sensor. Measure resistance between test pin No. 45 and test pins No. 26, 40, 46 and 60. If any reading is less than 10,000 ohms, repair short circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If all readings are 10,000 ohms or more, replace MAP/BARO sensor. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 5) to step 7). No test procedures have been omitted.
6. 7) KOER Code 126: Check For EGR-Related Codes Code 126 indicates MAP/BARO signal is out of self-test range during KOER SELF-TEST. Possible causes for this code are: Excess EGR flow. Damaged or misrouted MAP/BARO sensor vacuum hose. Faulty MAP/BARO sensor. If Code 326, 327, 328, 332, 334, 336 or 337 is present, perform applicable CIRCUIT TEST. See «DIAGNOSTIC TROUBLE CODE REFERENCE CHARTS»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If codes are not present, go to next step.
7. 8) Check MAP Sensor Operation Turn ignition off. Disconnect vacuum hose from MAP sensor. Connect vacuum pump to MAP sensor, and apply 18 in. Hg. If vacuum does not hold, replace sensor and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If MAP sensor holds vacuum, release vacuum and go to next step.
8. 9) Attempt To Eliminate Code 126 Plug MAP sensor vacuum supply hose. Start engine, and run it at 1400-1600 RPM. Slowly apply 15 in. Hg to MAP sensor. Perform «KOER SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . Check for Code 126, disregarding any other codes at this time. If Code 126 is still present, replace MAP sensor. If Code 126 is not present, inspect MAP sensor vacuum supply hose. If hose is okay, service other codes at this time. If no other code is present, check engine mechanical condition for cause of low vacuum.
9. 10) Code 129: Repeat Dynamic Response Test Code 129 indicates MAP sensor output did not change enough during dynamic response test. Possible causes for this code are: System failed to detect Wide Open Throttle (WOT). Damaged or misrouted MAP/BARO sensor vacuum hose. Faulty MAP sensor. Repeat «KOER SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . Ensure complete WOT is performed during dynamic response portion of test. If KOER Code 129 is still present, go to next step. If code is not present, service any other codes as necessary.
10. 11) Continuous Memory Code 128: Check Vacuum Hoses Continuous Memory Code 128 indicates MAP sensor vacuum has not changed more than 2 in. Hg during normal vehicle operation. Possible causes for this code are: MAP sensor vacuum hose is improperly routed, blocked or is leaking. MAP sensor is leaking. Check vacuum lines for correct routing. Refer to Vehicle Emission Control Identification (VECI) decal. Check for loose connections, kinks and blockage. Repair vacuum lines as necessary. If vacuum lines are okay, go to next step.
11. 12) Check MAP Sensor Operation Turn ignition off. Disconnect vacuum supply hose from MAP sensor. Attach vacuum pump to MAP sensor. Apply 18 in. Hg to MAP sensor. If MAP sensor holds vacuum, release vacuum and go to next step. If sensor does not hold vacuum, replace MAP sensor and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
12. 13) Verify Vacuum To MAP Sensor Decreases During Dynamic Response Test Turn ignition off. Use a "T" fitting to install a vacuum gauge in MAP sensor vacuum hose. Perform «KOER SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) while observing vacuum gauge. If vacuum decreases by more than 10 in. Hg during dynamic response test, replace MAP sensor and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If vacuum does not decrease by more than 10 in. Hg, EEC-IV system is okay. Check for engine mechanical problems affecting engine vacuum. NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 13) to step 90). No test procedures have been omitted.
13. 90) Continuous Memory Code 126 Code 126 indicates MAP/BARO sensor was out of self-test range (1.4-1.6 volts) during normal driving conditions. Possible causes for this code are: Faulty MAP/BARO sensor. Faulty wiring harness or connectors. Unusually high or low barometric pressure. Enter «CONTINUOUS MONITOR MODE (WIGGLE TEST)»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__continuous-monitor-mode-wiggle-test) . Observe test equipment while performing following: Connect a vacuum pump to MAP/BARO sensor. Slowly apply 25 in. Hg to sensor. Slowly bleed off vacuum from sensor. Lightly tap on sensor (to simulate road shock). Wiggle sensor connector. If a fault is indicated, disconnect sensor and inspect connectors. Repair if necessary. If connectors are okay, replace MAP/BARO sensor. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If a fault is not indicated, go to next step.
14. 91) Check EEC-IV Wiring Harness Stay in wiggle test. Observe analog VOM or scan tester for indication of fault while bending or wiggling small sections of harness from sensor connector to firewall, and from firewall to PCM. If fault is indicated, isolate fault in harness and repair as necessary. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If no fault is indicated, go to next step.
15. 92) Check PCM & Wiring Harness Connectors Turn ignition off. Disconnect PCM 60-pin connector. Inspect connectors and terminals for damage. Repair as necessary. If connectors and terminals are okay, fault cannot be duplicated at this time. Testing is complete. Refer to INTERMITTENTS in the «TESTS W/O CODES»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wo-codes) article.

If possible, measure output voltage of several known good MAP/BARO sensors on available vehicles. Average voltage reading will be typical for location and time of testing.

Perform this test when during QUICK TEST procedure or if directed by other diagnostic tests. This test is intended to diagnose

1. Knock sensor.
2. Wiring harness circuits (KS and SIG RTN).
3. Powertrain Control Module (PCM).

To prevent replacement of good components, be aware the following non-EEC related areas may be cause of problem

Scheme 39

1. Poor fuel quality.
2. Engine mechanical condition.
3. Ignition timing. (Scheme 39): Knock Sensor Circuits & Connector Terminals

1. Code 225: Generate Knock Signal Manually Code 225 indicates Knock Sensor (KS) signal was not received by PCM during dynamic response (goose) check in KOER SELF-TEST. Possible causes for this fault are: Faulty Knock Sensor (KS). Open or shorted harness. Faulty PCM. Disconnect PCM 60-pin connector. Inspect connector terminals for damage and repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM connected. Turn ignition on. Measure DC voltage between test pins No. 23 and No. 46 at breakout box. If DC voltage is 2.4-2.6 volts, go to next step. If DC voltage is less than 2.4 volts, go to step 4). If DC voltage is more than 2.6 volts, go to step 5).
2. Check KS Voltage Increase Start engine. Leave DVOM test leads connected to test pins No. 23 and No. 46. Monitor AC voltage at idle and at 3000 RPM. If AC voltage increases, replace PCM and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If AC voltage does not increase, go to next step.
3. Check Continuity Of KS & SIG RTN Circuits Turn ignition off. Disconnect knock sensor (both sensors) wiring harness connector. Measure resistance between SIG RTN terminal at KS wiring harness connector and test pin No. 46 at breakout box. Also, measure resistance between KS terminal at wiring harness connector and test pin No. 23 at breakout box. If either reading is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If both readings are less than 5 ohms, go to next step.
4. Check KS Circuit For Short To Ground Turn ignition off. Measure resistance between test pin No. 23 and test pins No. 40, 46 and 60 at breakout box. If all readings are 10,000 ohms or more, replace knock sensor. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If Code 225 is still present, replace PCM. If any reading is less than 10,000 ohms, repair short circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
5. Check KS Circuit For Short To Voltage Ensure PCM and KS are disconnected. Turn ignition on. Measure voltage between test pins No. 23 and 40. If voltage is 0.5 volt or more, repair short circuit in wiring harness. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If voltage is less than 0.5 volt, replace PCM. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .

Perform this test only when directed by QUICK TEST. This test is intended to diagnose the following

1. TP sensor.
2. Wiring harness circuits (TP, SIG RTN and VREF).
3. Powertrain Control Module (PCM).

Normal range of throttle angle measurement for TP sensor is 0-85 degrees. To pass QUICK TEST procedure, range of throttle rotation (in degrees) must be within 3 percent of specification. (Scheme 41)

To prevent replacement of good components, be aware the following non-EEC related areas may be at fault

Scheme 40

Scheme 41

1. Idle speed.
2. Binding throttle shaft or linkage.
3. TP sensor not seated. (Scheme 40): TP Sensor Circuits & Connector Terminals TEST PIN WIRE COLOR IDENTIFICATION Application Wire Color TEST PIN NO. 26 (VREF) Brown/White TEST PIN NO. 46 (SIG RTN) Gray/Red TEST PIN NO. 47 (TP) Gray/White (Scheme 41): TP Sensor Specification Chart

1. 1) KOER Code 121: Check For Other Codes KOER Code 121 indicates TP sensor rotational setting may be out of self-test range. Possible causes for this fault are: Binding throttle linkage. TP sensor not seated correctly. Faulty TP sensor. Faulty Powertrain Control Module (PCM). Perform «KOER SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). Check for Code 327. If Code 327 is present with Code 121, service Code 327 and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If Code 327 is not present with Code 121, go to next step.
2. 2) Code 121: Check For Binding Throttle Plate Inspect throttle body for binding. If throttle body is binding, check for binding throttle or cruise control linkage, vacuum line or harness interference. Repair as necessary, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If no mechanical problem is found, go to next step.
3. 3) Code 123: Attempt To Generate Code 122 Code 123 indicates TP sensor signal is more than self-test maximum value. Possible causes for this fault are: TP sensor not seated properly. Faulty TP sensor. Short circuit to power. Faulty PCM. Turn ignition off. Disconnect TP sensor wiring harness connector. Inspect and repair connector pins if damaged. Repeat «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test). Disregard all other codes at this time. If Code 122 is not displayed, go to step 5). If Code 122 is displayed, go to next step.
4. 4) Check VREF Circuit Voltage Turn ignition on. Measure voltage between VREF and SIG RTN terminals at TP sensor wiring harness connector. If reading is 4-6 volts, replace TP sensor and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If reading is not 4-6 volts, reconnect sensor and go to «CIRCUIT TEST C»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
5. 5) Check TP Circuit For Short To Power Turn ignition off. Leave TP sensor disconnected. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pin No. 47 and test pins No. 26 and 57 at breakout box. If any resistance is less than 10,000 ohms, repair short circuit in wiring harness. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If both resistances are 10,000 ohms or more, replace PCM. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 5) to step 10). No test procedures have been omitted.
6. 10) Code 122: Attempt To Generate Code 123 Or 121 Code 122 indicates TP signal is less than minimum self-test value. (Scheme 41) Possible causes for this fault are: TP sensor not seated correctly. Faulty TP sensor. Open circuit in wiring harness. Grounded circuit in wiring harness. Faulty PCM. Turn ignition off. Disconnect TP sensor from harness. Install a jumper wire between VREF and TP terminals at TP sensor wiring harness connector. Perform «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test). If no codes are generated, remove jumper wire and go to step 13). If Codes 123 and 121 are not present, remove jumper wire and go to next step. If either Code 123 or 121 is displayed, replace TP sensor and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
7. 11) Check VREF Circuit Voltage Turn ignition on. Measure voltage between VREF and SIG RTN terminals at TP sensor wiring harness connector. If voltage is not 4-6 volts, turn ignition off. Reconnect all components and go to «CIRCUIT TEST C»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If voltage is 4-6 volts, go to next step.
8. 12) Check TP Sensor Circuit Continuity Turn ignition off. Leave TP sensor disconnected. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between TP terminal at TP sensor wiring harness connector and test pin No. 47. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If resistance is less than 5 ohms, go to next step.
9. 13) Check TP Circuit For Shorts To Ground Turn ignition off. Leave TP sensor disconnected. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. With breakout box installed and PCM disconnected, measure resistance between test pin No. 47 and test pins No. 40, 46 and 60 at breakout box. If any reading is less than 10,000 ohms, repair short circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If all readings are 10,000 ohms or more, replace PCM. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 13) to step 20). No test procedures have been omitted.
10. 20) Code 167: Repeat Dynamic Response Test KOER Code 167 indicates TP sensor did not exceed 25 percent rotation during dynamic response portion of KOER SELF-TEST. A complete Wide Open Throttle (WOT) must be performed during dynamic response portion of test. Perform «KOER SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). Ensure a WOT is performed during dynamic response portion of test. If Code 167 is still present, go to next step. If Code 167 is not present, system is unable to duplicate Code 167 at this time. Service any other KOER codes. If no other service codes are present, testing is complete.
11. 21) Check TP Sensor Movement During Dynamic Response Test Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM connected. Set DVOM on 20-volt scale. Connect DVOM between test pins No. 46 and 47 at breakout box. Perform «KOER SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) and ensure proper WOT is completed during dynamic response test. If DVOM reading exceeds 3.5 volts during dynamic response test, replace PCM. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If reading does not exceed 3.5 volts, ensure TP sensor is correctly installed and adjusted. If TP sensor is correctly installed and adjusted, replace TP sensor. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 21) to step 90). No test procedures have been omitted.
12. 90) Continuous Memory Code 123 This test monitors TP sensor under simulated road conditions. Enter wiggle test. See «CONTINUOUS MONITOR MODE (WIGGLE TEST)»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__continuous-monitor-mode-wiggle-test) under QUICK TEST. Connect DVOM or diagnostic tester to STO terminal of Data Link Connector (DLC). While slowly opening throttle to WOT, observe DVOM or diagnostic tester for indication of fault. Slowly bring throttle to closed position. Lightly tap TP sensor and wiggle harness connector. This test checks for open or short in TP sensor and wiring harness. If no fault is indicated, go to step 92). If fault is indicated, go to next step.
13. 91) Measure TP Circuit Voltage While Exercising TP Sensor Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM connected. Stay in wiggle test (as in previous step). Connect DVOM between test pins No. 46 and 47. Set DVOM on 20-volt scale. With ignition on and engine off, observe DVOM and repeat step 90). If fault occurs at less than 4.25 volts, inspect TP sensor connectors and terminals. If connectors and terminals are okay, replace TP sensor, clear codes and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If fault does not occur at less than 4.25 volts, TP sensor over-travel may have caused Continuous Memory Code 123. TP sensor is okay. Go to step 92) to check wiring harness.
14. 92) Check EEC-IV Wiring Harness While in wiggle test, bend and shake small sections of EEC-IV harness from TP sensor wiring harness connector to firewall and from firewall to PCM while observing analog voltmeter or scan tester. If fault is indicated, isolate fault in wiring and repair as necessary. Clear codes, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If no fault is indicated, go to next step.
15. 93) Check PCM & Harness Connectors Turn ignition off. Disconnect PCM 60-pin connector from breakout box. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Clear codes from PCM memory, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If connectors and terminals are okay, fault cannot be duplicated at this time. Continuous Memory Code 123 testing is complete.
16. 94) Continuous Memory Code 122 Enter wiggle test. See «CONTINUOUS MONITOR MODE (WIGGLE TEST)»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__continuous-monitor-mode-wiggle-test) under QUICK TEST. Connect DVOM or diagnostic tester to STO terminal of Data Link Connector (DLC). Observe DVOM or diagnostic tester for indication of fault while performing the following: Slowly open throttle to WOT. Slowly bring throttle to closed position. Lightly tap TP sensor and wiggle connector. If fault is indicated, disconnect TP sensor. Inspect connectors and terminals. If connectors and terminals are okay, replace TP sensor. Clear codes from PCM memory, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If no fault is indicated, go to next step.
17. 95) Check EEC-IV Wiring Harness Stay in wiggle test (as in previous step). Bend, wiggle and shake small sections of EEC-IV harness from TP sensor wiring harness connector to firewall and from firewall to PCM while observing analog voltmeter or scan tester. If fault is indicated, isolate fault in wiring and repair as necessary. Clear codes from PCM memory, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If no fault is indicated, go to next step.
18. 96) Check PCM & Harness Connectors Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Clear codes from PCM memory, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If connectors and terminals are okay, fault cannot be duplicated at this time. Continuous Memory Code 122 testing is complete.

Perform this test only when instructed during QUICK TEST or if directed by other test procedures. This CIRCUIT TEST is intended to diagnose

1. VREF, DPFE, PFE, SIG RTN, EVR and VPWR harness circuits.
2. DPFE sensor.
3. PFE sensor.
4. EVR solenoid.
5. EGR valve assembly.
6. EVR and PFE/DPFE vacuum lines.
7. Powertrain Control Module (PCM).

To prevent replacement of good components, be aware the following non-EEC components may be at fault

Scheme 42

Scheme 43

Scheme 44

1. Faulty or damaged EGR valve.
2. Restricted exhaust system.
3. Damaged vacuum reservoir or canister. (Scheme 42): Identifying DPFE Sensor Connector Terminals (Scheme 43): Identifying PFE Sensor Connector Terminals (Scheme 44): Identifying EVR Solenoid Connector Terminals TEST PIN WIRE COLOR IDENTIFICATION Application Wire Color TEST PIN NO. 26 (VREF) Brown/White TEST PIN NO. 27 (PFE/DPFE) Brown/Light Green TEST PIN NO. 33 (EVR) Brown/Pink TEST PIN NO. 37/57 (VPWR) Red TEST PIN NO. 46 (SIG RTN) Gray/Red PFE SENSOR SPECIFICATIONS Pressure (psi) Vacuum (In. Hg) (1) Voltage 1.82 3.70 4.75 1.36 2.79 4.38 0.91 1.85 4.00 0.46 0.94 3.63 0 0 3.25 -2.47 -5.03 1.22 -3.63 -7.40 0.25 (1) Values may vary by 15 percent. DPFE SENSOR SPECIFICATIONS Pressure (psi) Vacuum (In. Hg) (1) Voltage 4.34 8.83 4.56 3.25 6.62 3.54 2.17 4.41 2.51 1.08 2.21 1.48 0 0 0.45 (1) Values may vary by 15 percent.

1. 1) Code 327: Generate Code 337 Code 327 indicates PFE/DPFE sensor signal is less than self-test minimum of 0.2 volt. Possible causes for this fault are: Faulty PFE/DPFE sensor. Open or shorted wiring harness circuits. Faulty PCM. Turn ignition off. Disconnect PFE/DPFE wiring harness connector at sensor. Install a jumper wire between VREF circuit and PFE or DPFE circuit at sensor wiring harness connector. Perform «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) . If no codes are present, remove jumper wire and go to step 4). If Code 337 is present, ignore all other codes and replace PFE/DPFE sensor. Remove jumper wire, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If Code 337 is not present, remove jumper wire and go to next step.
2. 2) Measure VREF Circuit Voltage With PFE/DPFE sensor disconnected, turn ignition on. Measure voltage between sensor wiring harness connector VREF and SIG RTN terminals. If voltage is 4-6 volts, go to next step. If voltage is not 4-6 volts, go to «CIRCUIT TEST C»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
3. 3) Check PFE/DPFE Circuit Continuity Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between PFE/DPFE terminal at sensor wiring harness connector and test pin No. 27 at breakout box. If resistance is more than 5 ohms, repair open circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If resistance is 5 ohms or less, go to next step.
4. 4) Check PFE/DPFE Circuit For Shorts To Ground & SIG RTN Turn ignition off. Measure resistance between test pin No. 27 and test pins No. 40, 46 and 60 at breakout box. If any reading is less than 10,000 ohms, repair short circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If all readings are 10,000 ohms or more, replace PCM. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
5. 5) Code 337: Generate Code 327 Code 337 indicates PFE/DPFE sensor signal is more than self-test maximum of 4.8 volts. Possible causes for this code are: Faulty PFE/DPFE sensor. Shorted vehicle harness circuits. Open SIG RTN circuit. Faulty Powertrain Control Module (PCM). Turn ignition off. Disconnect PFE/DPFE sensor. Repeat «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) . Check for Code 327. Ignore all other codes at this time. If Code 327 is not present, go to step 7). If Code 327 is present, go to next step.
6. 6) Measure VREF Circuit Voltage With PFE/DPFE sensor disconnected, turn ignition on. Measure voltage between VREF and SIG RTN terminals at PFE/DPFE sensor wiring harness connector. If voltage is 4-6 volts, replace PFE/DPFE sensor. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If voltage is not 4-6 volts, go to «CIRCUIT TEST C»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
7. 7) Check PFE/DPFE Circuit For Shorts To Power With ignition off, disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pin No. 27 and test pins No. 26, 37 and 57. If any reading is less than 10,000 ohms, repair short circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If all readings are 10,000 ohms or more, replace PCM. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
8. 8) Code 335: Verify KOER Codes Code 335 indicates PFE/DPFE sensor is out of self-test range (2.6-4.2 volts) and may be faulty. PFE/DPFE system can detect lack of pressure in exhaust system. A garage exhaust ventilation system, installed during KOEO SELF-TEST, may cause PFE/DPFE sensor to generate Code 335. Remove exhaust ventilation system. Repeat «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) . Service codes as necessary. If no codes are present during KOEO SELF-TEST, complete QUICK TEST. If Code 335 is present during KOEO SELF-TEST, go to next step.
9. 9) Check PFE/DPFE Sensor Pressure Input Hose Remove pressure feed tube from PFE/DPFE sensor. Inspect tube, including PFE/DPFE inlet, for blockage. Repair if necessary, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If no blockage is found, go to next step.
10. 10) Measure VREF Circuit Voltage With ignition off, disconnect PFE/DPFE sensor wiring harness connector. Turn ignition on. Measure voltage between VREF and SIG RTN terminals at PFE/DPFE sensor wiring harness connector. If voltage is 4-6 volts, replace PFE/DPFE sensor and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If voltage is not 4-6 volts, go to «CIRCUIT TEST C»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
11. 11) Code 558: Measure EVR Solenoid Resistance Code 558 indicates failure in EVR solenoid or circuit. Possible causes for this code are: Faulty EVR solenoid. Faulty Powertrain Control Module (PCM). Open or shorted wiring harness circuit. Turn ignition off. Disconnect EVR solenoid connector. Measure resistance between EVR solenoid terminals. If resistance is 25-70 ohms, go to next step. If resistance is not 25-70 ohms, replace EVR solenoid. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
12. 12) Check VPWR Circuit Voltage Set DVOM on 20-volt scale. Turn ignition on. Measure voltage between VPWR terminal at EVR solenoid wiring harness connector and negative battery terminal. If voltage is less than 10.5 volts, repair open circuit and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If voltage is 10.5 volts or more, go to next step.
13. 13) Check EVR Circuit Continuity Turn ignition off. Leave EVR solenoid connector disconnected. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between EVR terminal at EVR solenoid wiring harness connector and test pin No. 33 at breakout box. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If resistance is less than 5 ohms, go to next step.
14. 14) Check EVR Circuit For Shorts To Power Or Ground Turn ignition off. Measure resistance between test pin No. 33 and pins No. 37, 40, 57 and 60 at breakout box. If any reading is less than 10,000 ohms, repair short circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If Code 558 is repeated, replace PCM. If all readings are 10,000 ohms or more, replace PCM. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 14) to step 20). No test procedures have been omitted.
15. 20) Code 326: Verify KOER Codes Code 326 indicates PFE circuit voltage is low during zero EVR duty cycle. Possible causes for this fault are: Obstructed vacuum line. Contaminated EVR filter. Faulty EVR solenoid. Faulty EGR valve. PFE/DPFE system can detect lack of pressure in exhaust system. A garage exhaust ventilation system, installed during KOER SELF-TEST, may cause PFE/DPFE sensor to generate Code 326. Temporarily remove exhaust ventilation system, and retest. If Code 326 is not present, service other codes present during «KOER SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If no code is present, testing is complete. If Code 326 is present, go to next step.
16. 21) Code 327 Code 327 indicates PFE/DPFE sensor signal is less than self-test minimum. Disconnect and plug EGR valve vacuum hose. Perform «KOER SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If Codes 327 or 326 are present, go to next step. If codes are not present, check EVR vent and vacuum hose to EGR valve for blockage. Repair as necessary. If vent and vacuum hose are okay, replace EVR solenoid and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
17. 22) Code 326 Or 327: Check PFE/DPFE Input Hoses With ignition off, check PFE/DPFE sensor pressure input hose for blockage and leaks. Repair as necessary. Connect all lines, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If no fault is found, go to next step.
18. 23) Check PFE/DPFE Voltage With Engine At Idle Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM connected. Start engine and allow to idle with transmission in Park or Neutral. Measure voltage between test pins No. 27 and 46 at breakout box. On DPFE sensor, if voltage is less than 2.9 volts, replace sensor. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . On PFE sensor, if voltage is less then 0.2 volt, go to next step. On either sensor, if voltage is more than specified, replace PCM. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
19. 24) Check EGR Valve For Binding Fault has been isolated to either EGR valve or PFE sensor. If engine runs rough at idle, EGR valve may not be fully seated. Remove EGR valve. Inspect EGR valve for signs of contamination, wear, carbon deposits, binding and other damage. Repair or replace as necessary. If EGR valve is okay, install EGR valve. Perform «KOER SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If Codes 327 or 326 is still present, replace EGR valve. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If either code is still present, replace PFE sensor. If codes are not present, original Code 327 or 326 was result of EGR valve not fully seating. Testing is complete.
20. 25) Codes 336 & 337: Check For Exhaust Restriction Code 336 indicates PFE circuit voltage is higher than expected at zero duty cycle. Code 337 indicates PFE circuit voltage is higher than self-test maximum. Possible causes for these codes are: Exhaust system restricted. PFE sensor faulty. Faulty PCM. Shorted harness circuits. Attach vacuum gauge to intake manifold. Connect tachometer to engine. Start engine and allow to idle. Observe vacuum gauge as engine speed is increased to 2000 RPM. Vacuum gauge needle should drop to zero and then quickly return to 16 in. Hg. If vacuum gauge needle movement is slow, check for restriction in exhaust system. Repair exhaust system as necessary. If vacuum gauge needle is quick, go to next step.
21. 26) Check PFE Sensor Output With Engine Idling Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM connected. Start engine and allow to idle with transmission in Park or Neutral. Measure voltage between test pins No. 27 and 46 at breakout box. If voltage is 3.0-3.5 volts, replace PCM and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If voltage is not 3.0-3.5 volts, go to next step.
22. 27) Check PFE & SIG RTN Harness Continuity Turn ignition off. Ensure PFE sensor is disconnected. Disconnect PCM 60-pin connector. Measure resistance between PFE terminal at PFE sensor wiring harness connector and test pin No. 27. Measure resistance between PFE SIG RTN terminal at PFE sensor wiring harness connector and test pin No. 46. If each resistance is less than 5 ohms, go to next step. If any resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
23. 28) Check PFE Harness Circuit For Short To Power Ensure ignition is off. With PFE sensor and PCM disconnected, measure resistance between test pin No. 27 and test pins No. 26, 37 and 57 at breakout box. If all readings are more than 10,000 ohms, replace PFE sensor. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If any reading is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 28) to step 30). No test procedures have been omitted.
24. 30) Code 332: Verify Vacuum At EGR Valve Code 332 indicates PFE/DPFE sensor input to PCM did not change after EVR solenoid received signal from PCM to open EGR valve. Possible causes for this fault are: Vacuum hose leaks or restrictions. Faulty PFE/DPFE sensor. Faulty EVR solenoid. Faulty EGR valve. Faulty Powertrain Control Module (PCM). Turn ignition off. Using a vacuum "T", connect vacuum gauge at EGR valve. Perform «KOER SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) while observing vacuum gauge. Disregard code output at this time. If vacuum reading is more than 1.0 in. Hg, go to step 34). If vacuum reading is 1.0 in. Hg or less, remove vacuum gauge and go to next step.
25. 31) Check Vacuum Input To EVR Solenoid Turn ignition off. Disconnect EVR vacuum hose. Connect EVR vacuum hose to vacuum gauge. Start engine and allow it to idle while observing vacuum gauge. If 15 in. Hg or more is present, replace EVR solenoid and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If less than 15 in. Hg is present, repair vacuum source and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 31) to step 34). No test procedures have been omitted.
26. 34) Check Vacuum At PFE/DPFE Inlet Hose(s) Turn ignition off. Disconnect and inspect PFE/DPFE vacuum hose for damage and repair as necessary. Reconnect vacuum hose. Disconnect and plug EGR valve vacuum hose. Connect a vacuum pump to EGR valve. Disconnect Idle Air Control (IAC) valve. If engine will not idle with IAC disconnected, open throttle until idle stabilizes. Slowly apply 5-10 in. Hg to EGR valve. Idle speed should drop more than 100 RPM with vacuum applied and should return to normal with vacuum released. If idle speed is as specified, EGR valve is functioning properly. Check EGR vacuum inlet hose. Replace hose as necessary. If vacuum hose is okay, go to next step. If idle speed is not as specified, remove and inspect EGR valve. Replace EGR valve as necessary. If EGR valve is okay, check for obstructed EGR valve passage way in intake manifold. Service as necessary.
27. 35) Attempt To Generate KOEO Code 337 Turn ignition off. Disconnect PFE/DPFE sensor. Connect a jumper wire between PFE/DPFE terminal and VREF terminal at PFE/DPFE sensor wiring harness connector. Perform «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) . If Code 337 is present, ignore all other codes and replace PFE/DPFE sensor. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If Code 337 is not present, remove jumper wire and go to next step.
28. 36) Measure VREF Circuit Voltage With PFE/DPFE sensor disconnected, turn ignition on. Measure voltage between VREF terminal and SIG RTN terminal at PFE/DPFE sensor wiring harness connector. If voltage is 4-6 volts, go to next step. If voltage is not 4-6 volts, go to «CIRCUIT TEST C»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
29. 37) Check PFE/DPFE Circuit Resistance Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between PFE/DPFE terminal at PFE/DPFE sensor wiring harness connector and test pin No. 27 at breakout box. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
30. 38) Check PFE/DPFE Circuit For Short To SIG RTN & Ground Turn ignition off. Measure resistance between PFE/DPFE terminal at PFE/DPFE sensor wiring harness connector and test pins No. 40, 46 and 60 at breakout box. If any reading is less than 10,000 ohms, repair short circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If all readings are 10,000 ohms or more, replace PCM. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 38) to step 50). No test procedures have been omitted.
31. 50) Codes 336 & 337: Check EVR Malfunction Code 336 indicates DPFE voltage is too high at zero duty cycle. Possible causes for these codes are: Vacuum hose routing. EGR valve faulty. EVR solenoid faulty. DPFE sensor faulty. Faulty PCM. Disconnect and plug EGR vacuum hose. Perform «KOER SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If Code 336 or 337 is present, go to next step. If Code 336 or 337 is not present, ensure vacuum hose routing is correct and EVR filter is clean. If okay, replace EVR solenoid. Reconnect all vacuum lines, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
32. 51) Check DPFE Sensor Output With Engine Idling Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM connected. Start engine and allow to idle with transmission in Park or Neutral. Measure voltage between test pins No. 27 and 46 at breakout box. If voltage is less than 0.7 volt at idle, replace PCM. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If voltage is 0.7 volt or more, go to next step.
33. 52) Check EGR Valve Remove EGR valve. Check EGR valve for carbon deposits, binding or other damage. Repair as necessary. Install EGR valve and repeat «KOER SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If Code 336 or 337 is still present, replace EGR valve and repeat «KOER SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If Code 336 or 337 is still present, replace DPFE sensor. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If Code 336 or 337 is not present, fault is intermittent and cannot be duplicated at this time. Original Code 336 or 337 was probably set because EGR valve was not fully seating. Testing is complete. NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 52) to step 90). No test procedures have been omitted.
34. 90) Intermittent Verification This step verifies if trouble code is due to an intermittent or hard fault. Perform «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) and «KOER SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) (if not already performed). Note all codes. If unable to perform KOER SELF-TEST because of a no-start or stall condition, go to step 101). If any codes are output during KOEO or KOER SELF-TEST (ignore continuous memory codes at end of KOEO), perform appropriate circuit test. See «DIAGNOSTIC TROUBLE CODE REFERENCE CHARTS»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If no codes are output during KOEO or KOER SELF-TEST, fault is intermittent. Go to next step.
35. 91) PFE/DPFE System Inspection Check for damaged or loose connectors. Check for loose or corroded connector pins. Inspect wiring harness for proper routing and insulation. Ensure component mounting and vacuum hose routing is correct. Ensure EVR solenoid filter is clean. Repair or replace as necessary. Clear codes and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If no faults are present, reconnect all components and go to next step.
36. 92) EGR Fault Code(s) In Continuous Memory Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If fault code(s) are present in KOEO SELF-TEST or KOER SELF-TEST, go to appropriate circuit test. If fault Code 326, 327, 336 or 337 is present in continuous memory only, go to next step. If fault Code 332 is present in continuous memory only, go to step 105).
37. 93) Continuous Memory Code 326, 327, 336 Or 337 If code is present, possible causes are: Damaged connectors or terminals. Open or shorted wiring harness. Faulty EGR valve operation. Faulty EVR solenoid operation. Circuit fault can be in wiring harness, component or PCM. Enter wiggle test. See «CONTINUOUS MONITOR MODE (WIGGLE TEST)»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__continuous-monitor-mode-wiggle-test) under QUICK TEST. Observe analog VOM or diagnostic tester for indication of fault while performing following steps. Grasp wiring harness near sensor connector while observing VOM or diagnostic tester for fault indication. Shake and bend small sections of harness, working from sensor toward firewall. Shake and bend harness from firewall to PCM. If fault is indicated, inspect connectors and terminals. Repair as necessary. If connectors and terminals are okay, replace PFE/DPFE sensor. Clear codes and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If no fault is indicated, go to next step.
38. 94) Stay in wiggle test. Observe analog VOM or scan tester for indication of fault while bending or wiggling small sections of harness from sensor connector to firewall, and from firewall to PCM. If fault is indicated, isolate fault in harness and repair as necessary. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If no fault is indicated, go to next step.
39. 95) Check PCM Wiring Harness Connector Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Clear codes, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If connector and terminals are okay but fault code is present, go to appropriate step as follows: Code 326 or 327 on models equipped with PFE; go to next step. Code 336 on models equipped with PFE; go to step 100). Code 336 or 337 on models equipped with DPFE; go to next step. If no codes are present, unable to duplicated and/or identify fault at this time. Testing is complete.
40. 96) Check EGR Valve Operation Turn ignition off. Disconnect vacuum hose from EGR valve. Connect vacuum pump to EGR valve. While observing EGR valve, slowly apply 10 in. Hg and release. If EGR valve does not operate smoothly, service or replace EGR valve. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If EGR valve operation is smooth, go to next step.
41. 97) Check EVR Solenoid & Hoses Turn ignition off. Inspect EVR solenoid vacuum hoses for contamination, moisture or restriction. Ensure EVR solenoid filter is clean. Repair or replace as necessary and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If no faults are found, reconnect all components and go to next step.
42. 98) Check EVR Solenoid For Short Circuit Turn ignition off. Disconnect vacuum hose from EGR valve. Connect vacuum pump to vacuum hose. Start engine and operate at idle. While observing vacuum gauge, tap on EVR solenoid and wiggle wiring harness connector. If vacuum gauge does not remain less than 1.0 in. Hg and has erratic increases, replace EVR solenoid and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If vacuum gauge remains less than 1.0 in. Hg with no erratic increases, leave vacuum gauge connected and go to next step.
43. 99) Check Wiring Harness Between EVR Solenoid & PCM With engine running, observe vacuum gauge while wiggling wiring harness connector between EVR solenoid and dash panel. Wiggle wiring harness between dash panel and PCM. If EGR vacuum increases, isolate short and repair as necessary. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If EGR vacuum does not increase, fault is intermittent and cannot be duplicated at this time. Testing is complete.
44. 100) Continuous Memory Code 336 (PFE) With ignition off, remove PFE sensor. Inspect PFE sensor inlet for liquids and/or blockage. Inspect PFE supply host to EGR valve base for liquids and/or blockage. Repair as necessary. Clear codes and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If PFE sensor and EGR supply hose are okay, fault is intermittent and cannot be duplicated at this time. Testing is complete.
45. 101) Check EGR Vacuum At Start-Up Disconnect and plug EGR vacuum hose. Start engine and allow to idle (if possible). If engine idle is correct, ensure EVR hoses are correctly routed. If hoses are okay, replace EVR solenoid. Clear codes and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If engine does not idle correctly, go to next step.
46. 102) Check EGR Valve Operation Turn ignition off. Disconnect vacuum hose from EGR valve. Connect vacuum pump to EGR valve. While observing EGR valve, slowly apply 10 in. Hg and release. If EGR valve does not operate smoothly or close completely, service or replace EGR valve. If EGR valve operation is okay, problem is not EGR related. Connect all components and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 102) to step 105). No test procedures have been omitted.
47. 105) Continuous Memory Code 332: Check EGR Valve Operation If code is present, possible causes are: EGR valve sticking closed. EGR valve diaphragm leaks. Faulty EVR solenoid operation. Loss of vacuum to or from EVR solenoid. Open in EVR VPWR or driver circuits. Leak or restriction in PFE/DPFE signal hoses. Turn ignition off. Disconnect vacuum hose from EGR valve. Connect vacuum pump to EGR valve. While observing EGR valve, apply 1.0-1.5 in. Hg. EGR valve should begin to open. Increase vacuum pump application to 4 in. Hg. EGR valve should be fully open. Increase vacuum pump application to 10 in. Hg. EGR valve should hold and maintain vacuum. If EGR valve does not perform as specified, repair or replace EGR valve as necessary. Clear codes and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If EGR valve is okay, go to next step.
48. 106) Inspect EVR Solenoid Hoses With ignition off, disconnect EVR vacuum hoses. Inspect vacuum hose for damage or restrictions. Repair as necessary. Clear codes and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If EVR vacuum hoses are okay, go to next step.
49. 107) Inspect PFE/DPFE Hoses With ignition off, remove PFE/DPFE hoses from sensor. Inspect hoses for contamination, leaks or restrictions. Repair as necessary. Clear codes and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If PFE/DPFE hoses are okay, go to next step.
50. 108) Check EVR Solenoid Ground Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM connected. Disconnect vacuum hose from EGR valve. Connect EGR vacuum hose to vacuum pump. Start engine and allow to idle. Connect jumper wire between test pins No. 33 and 40 at breakout box. EVR solenoid should turn on. Observe vacuum gauge while tapping on EVR solenoid. Wiggle wiring harness and connector. A sudden drop in vacuum indicates a fault in the system. If a sudden drop in vacuum occurs, isolate fault and repair as necessary. Clear codes and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If no drop in vacuum occurs, go to next step.
51. 109) Check For Obstructed EGR Passage Turn ignition off. Inspect EGR port for sludge obstruction (it may be necessary to remove intake manifold). If excessive sludging is present in intake manifold, clean and service as necessary. Reconnect all components, clear codes and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) suspect. If excessive sludge is not present in intake manifold, fault cannot be identified at this time. Testing is complete.

EVR solenoid receives variable input from PCM, which allows it to control vacuum level to EGR valve. Vacuum not used by EGR is routed to EVR solenoid and vented to atmosphere.

Perform this test when instructed by QUICK TEST or if directed by other test procedures. To prevent replacement of good components, be aware a damaged EGR valve may be cause of problem. This CIRCUIT TEST is intended to diagnose the following

Scheme 45

1. EVP sensor.
2. EVR solenoid.
3. EGR valve assembly.
4. Powertrain Control Module (PCM).
5. EGR and EVR vacuum lines.
6. Wiring harness circuits (VREF, EVP, SIG RTN, EVR and VPWR). (Scheme 45): Identifying EVP Sensor & EVR Solenoid Connector Terminals TEST PIN WIRE COLOR IDENTIFICATION Application Wire Color TEST PIN NO. 26 (VREF) Brown/White TEST PIN NO. 27 (EVP) Brown/Light Green TEST PIN NO. 33 (EVR) Brown/Pink TEST PIN NO. 46 (SIG RTN) Gray/Red NOTE: EVR sensor is preloaded when attached to EGR valve. Valve failure causing EVR sensor to lose preload may set Code 327.

1. 1) Code 327: Attempt To Generate Code 337 Code 327 indicates EVP sensor signal is less than self-test minimum of 0.2 volt. Possible causes for this fault are: Faulty EVP sensor. Faulty EGR valve. Open or grounded harness. Faulty PCM. Turn ignition off. Disconnect EVP sensor wiring harness connector. Install a jumper wire between VREF terminal and EVP terminal at EVP sensor wiring harness connector. Repeat «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) and «KOER SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . Check for Code 337. Ignore all other codes at this time. If Code 337 is present, replace EVP sensor. Remove jumper wire and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If Code 337 is not present, remove jumper wire and go to next step. If no codes are present, remove jumper wire and go to step 4).
2. 2) Check VREF Circuit Voltage Disconnect EVP sensor. Turn ignition on. Measure voltage between VREF terminal and SIG RTN terminal at EVP sensor wiring harness connector. If voltage is 4-6 volts, go to next step. If voltage is not 4-6 volts, go to «CIRCUIT TEST C»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
3. 3) Check EVP Circuit Resistance Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between EVP terminal at EVP sensor wiring harness connector and test pin No. 27. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If resistance is less than 5 ohms, go to next step.
4. 4) Check EVP Circuit For Shorts To Ground Ensure ignition is off and EVP sensor is disconnected. Set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 27 and test pins No. 40, 46 and 60. If any reading is less than 10,000 ohms, repair short circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If all readings are 10,000 ohms or more, replace PCM. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
5. 5) Code 337: Attempt To Generate Code 327 Code 337 indicates EVP sensor signal is more than self-test maximum of 4.81 volts. Possible causes for this fault are: Faulty EVP sensor. Faulty PCM. Short to power in vehicle harness. Open in SIG RTN circuit. Turn ignition off. Disconnect EVP sensor. Perform «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) and «KOER SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . Check for Code 327. Ignore all other codes at this time. If Code 327 is present, go to next step. If Code 327 is not present, go to step 7).
6. 6) Check VREF Circuit Voltage Turn ignition on. Measure voltage between VREF terminal and SIG RTN terminal at EVP sensor wiring harness connector. If voltage is 4-6 volts, replace EVP sensor. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If voltage is not 4-6 volts, go to «CIRCUIT TEST C»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
7. 7) Check EVP Circuit For Short To Power Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pin No. 27 and test pins No. 26 and 57 at breakout box. If any reading is less than 10,000 ohms, repair short circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If all readings are 10,000 ohms or more, replace PCM. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 7) to step 10). No test procedures have been omitted.
8. 10) Code 558: Check EVR Solenoid Resistance Code 558 indicates fault in EVR solenoid circuit. Possible causes for this fault are: Faulty EVR solenoid. Faulty PCM. Shorted or open harness. Turn ignition off. Disconnect EVR solenoid connector. Measure resistance between EVR solenoid terminals. If resistance is not 20-70 ohms, replace EVR solenoid assembly and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If resistance is 20-70 ohms, go to next step.
9. 11) Check VPWR Circuit Voltage Disconnect EVR solenoid. Turn ignition on. Measure voltage between negative battery terminal and VPWR terminal at EVR solenoid wiring harness connector. If reading is less than 10.5 volts, repair open in VPWR circuit and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If reading is 10.5 volts or more, go to next step.
10. 12) Check EVR Circuit Continuity Turn ignition off. Disconnect EVR solenoid. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between EVR terminal at EVR solenoid wiring harness connector and test pin No. 33. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
11. 13) Check EVR Circuit For Shorts To Power Or Ground Turn ignition off. Measure resistance between test pin No. 33 and test pins No. 37, 40, 46, 57 and 60 at breakout box. If any reading is less than 10,000 ohms, repair short circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If code is repeated, replace EVR solenoid. If all readings are 10,000 ohms or more, replace PCM. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 13) to step 20). No test procedures have been omitted.
12. 20) Code 334: Check For Code 558 Code 334 indicates EGR valve and/or EVP is not fully seated in closed position. EVP voltage signal, in closed position, is more than self-test maximum of 0.67 volt. Because of EVP sensor preload, determining whether EGR valve is seated or EVP sensor contacts EGR valve stem is difficult. Possible causes for this fault are: Poor contact in EVP sensor circuit. EGR valve not seated. Faulty EGR valve. Faulty EVP sensor. Faulty EVP solenoid. Faulty PCM. Turn ignition off. Perform «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) . If Code 558 is present, return to step 10). If Code 558 is not present, go to next step.
13. 21) Perform SELF-TEST Without EGR Remove and plug vacuum line to EGR valve. Perform «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) and «KOER SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If Code 334 is still present, go to next step. If Code 334 is not present, check EVR solenoid for obstructions. If no obstructions are present, replace EVR solenoid. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
14. 22) Check EGR Valve & EVP Sensor Operation Turn ignition off. Disconnect EVP sensor. Inspect harness and connector, and service as necessary. Remove and plug vacuum hose to EGR valve. Install vacuum gauge at EGR valve vacuum port. Operate EGR valve by applying and releasing vacuum. Install vacuum hose to EGR valve and wiring harness connector to EVP sensor. Repeat «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) and «KOER SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If Code 334 is present, go to next step. If Code 334 is not present, original fault was caused by poor continuity at EVP sensor connector or binding/sticking of EGR valve stem.
15. 23) Check EVP Signal Voltage Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect PCM to breakout box. Turn ignition on. Measure voltage between test pins No. 27 and 46 at breakout box. If voltage is less than 0.67 volt, replace PCM. Remove breakout box and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If voltage is more than 0.67 volt, go to next step.
16. 24) EGR Valve/EVP Sensor Fault Isolation Remove EGR valve and EVP sensor. Inspect valve and sensor for binding, carbon deposits, excessive wear and damage. Repair or replace EGR valve as necessary. Install EGR valve and EVP sensor. Perform «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) and «KOER SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If Code 334 is still present, replace EGR valve. Remove breakout box and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If Code 334 is not present, original code was a result of EGR valve contamination, binding or a faulty EVP sensor. Testing is complete.
17. 25) Code 328: Check EVP Sensor & EGR Valve Operation Code 328 indicates EVP sensor is lower than normal (0.24 volt) in closed position. Because of EVP sensor preload, determining whether EGR valve has malfunctioned or EVP sensor has an abnormally high resistance is difficult. Possible causes for this fault are: Faulty EGR valve. Faulty EVP sensor. Faulty PCM. Poor continuity in EVP sensor circuit. Turn ignition off. Disconnect EVP sensor wiring harness connector. Inspect harness and connector, and service as necessary. Remove EGR valve vacuum hose. Attach vacuum pump to EGR valve. Operate EGR valve by applying and releasing vacuum. Install vacuum hose to EGR valve and wiring harness connector to EVP sensor. Repeat «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) and «KOER SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If Code 328 is not present, original fault was caused by poor continuity at EVP sensor connector or binding/sticking of EGR valve stem. If Code 328 is present, go to next step.
18. 26) Check EVP Signal Voltage Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect PCM to breakout box. Remove and plug EGR valve vacuum hose. Connect vacuum pump to EGR valve vacuum hose. Turn ignition on. Measure voltage between test pins No. 27 and 46 at breakout box while performing following: apply 6 in. Hg to EGR valve and then slowly bleed vacuum completely off. If voltage does not drop to less than 0.24 volt, replace PCM. Remove breakout box and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If voltage drops to less than 0.24 volt, go to next step.
19. 27) Substitute EVP Sensor On Original EGR Valve Turn ignition off. Install a known good EVP sensor on original EGR valve. Ensure all hoses and electrical connectors are attached. Perform «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) and «KOER SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If Code 328 is present, replace EGR valve. Remove breakout box and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If Code 328 is not present, replace original EVP sensor. Testing is complete. NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 27) to step 40). No test procedures have been omitted.
20. 40) KOER Code 332: Check Vacuum At EGR KOER Code 332 indicates EVP sensor input did not change after PCM signaled operation of EGR. Because Code 558 was not retrieved in KOEO SELF-TEST, EVR solenoid electrical function is okay. Lack of Code 328 or 334 indicates EVP sensor is within closed position specification. Possible causes for this fault are: Leaking vacuum hose. Restricted vacuum hose. Restricted EVR solenoid filter. Faulty EVR solenoid. Faulty EVP sensor. Faulty EGR valve. Turn ignition off. Disconnect vacuum hose from EGR valve. Connect a vacuum gauge at open end of hose. Perform «KOER SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) while observing vacuum gauge. If vacuum reading is more than 1.0 in. Hg, remove vacuum gauge and go to step 43). If reading is 1.0 in. Hg or less, remove vacuum gauge and reconnect EGR vacuum hose. Go to next step.
21. 41) Verify Vacuum Supply To EVR Solenoid Turn ignition off. Disconnect EVR solenoid vacuum hose. Install vacuum gauge at vacuum hose. Start engine and check vacuum. If reading is 10 in. Hg or more, go to next step. If reading is less than 10 in. Hg, check vacuum line to EVR solenoid. Repair if necessary. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
22. 42) Check Vacuum Between EVR Solenoid & EGR Valve Check vacuum hose for cracks, loose connections, blockage and kinks. Repair or replace vacuum hose as necessary, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If vacuum hose is okay, check EVR solenoid filter for obstructions. Replace if necessary. If filter is okay, replace EVR solenoid. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
23. 43) Check EVP Sensor & EGR Valve Operation Turn ignition off. Disconnect EVP sensor. Inspect connector and harness for damage, and service as necessary. Remove vacuum hose from EGR valve. Connect vacuum pump to EGR valve. Operate EGR valve operation by applying and releasing vacuum. Connect vacuum line to EGR valve. Connect wiring harness connector to EVP sensor. Repeat «KOER SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If Code 332 is still present, go to next step. If Code 332 is not present, original code was set either by poor continuity at EVP sensor connector or sticking EGR valve. Testing is complete.
24. 44) Check EGR Valve Function Turn ignition off. Install tachometer. Remove Idle Air Control (IAC) wiring harness connector. Remove and plug vacuum hose to EGR valve. Start engine, and allow it to idle with transmission in Neutral. Ensure idle speed is adjusted correctly. Connect vacuum pump to EGR valve. Slowly apply 5-10 in. Hg. If engine idle decreases more than 100 RPM with vacuum applied and returns to correct idle with vacuum released, EGR valve is okay. Replace EVP sensor. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If vacuum does not drop more than 100 RPM with vacuum applied, repair or replace EGR valve. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 44) to step 90). No test procedures have been omitted.
25. 90) Continuous Memory Code 327, 328 Or 337 Continuous Memory Code 327 or 328 indicates EGR valve closed further than normal or EVP circuit failed with intermittent low voltage sometime during engine operation. Code 337 indicates EVP signal to PCM was above maximum self-test limit sometime during engine operation. Possible causes for these faults are: Poor continuity in EVP wiring harness or connectors. Intermittent open or short in EVP sensor or wiring harness. Faulty EVP sensor. Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect PCM to breakout box. Turn ignition on. Connect DVOM between test pins No. 27 and 46 at breakout box. Wiggle wiring harness and lightly tap on EVP sensor. If voltage remains steady at .24-.67 volt, go to next step. If voltage is erratic or not within .24-.67 volt range, remove and inspect EVP sensor wiring harness connector. Repair or replace as necessary. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If sensor connector is okay, replace EVP sensor. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
26. 91) Check Wiring Harness Connect DVOM between test pins No. 27 and 46 at breakout box. Turn ignition on. Observe DVOM for fault indication while wiggling and bending small sections of wiring harness near sensor, working from sensor toward dash panel. Wiggle and bend wiring harness from firewall to PCM. If fault is indicated, isolate fault and repair wiring harness. Clear codes, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If fault is not found, go to next step.
27. 92) Measure EVP Signal Voltage While Exercising EGR Valve Remove and plug vacuum hose to EGR valve. Install vacuum gauge at EGR valve vacuum hose. Turn ignition on. Measure voltage between test pins No. 27 and 46 at breakout box while performing following: apply 5-10 in. Hg to EGR valve and slowly bleed vacuum completely off. If voltage steadily fluctuates between 0.24-4.81 volts, problem is intermittent and cannot be duplicated at this time. If voltage does not fluctuate steadily between 0.24-4.81 volts, replace EVP sensor. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 92) to step 110). No test procedures have been omitted.
28. 110) Continuous Memory Code 332 Code 332 indicates EGR valve did not open with engine at normal operating temperature and with EVR solenoid signal present sometime during engine operation. Possible causes of this fault are: Fault in vacuum line. Faulty EGR valve. Open or shorted EVR circuit. Turn ignition off. Disconnect vacuum hose at EGR valve. Connect vacuum pump to valve. Apply 10-20 in. Hg to EGR valve. If EGR valve opens and holds vacuum, go to next step. If EGR valve does not open and hold vacuum, service or replace EGR valve as necessary. Clear codes and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
29. 111) Check EVR Solenoid Vacuum Hoses Disconnect and vacuum hose from EGR valve to EVR solenoid, and vacuum hose from EVR solenoid to vacuum source. Check hoses for obstructions, cracks, kinks and leaks. Replace hoses as necessary. Clear codes and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If vacuum hoses are okay, go to next step.
30. 112) Check EVR Solenoid & Wiring Harness For Intermittent Turn ignition off. Disconnect vacuum hose from EGR valve. Connect EGR valve hose to vacuum gauge. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect PCM to breakout box. Start engine, and allow it to idle. Connect jumper wire between test pins No. 33 and 40. Tap on EVR sensor and wiggle wiring harness while observing vacuum gauge. If vacuum gauge shows a sudden drop in vacuum, isolate cause and repair as necessary. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If vacuum gauge does not show a drop in vacuum, problem is intermittent and cannot be duplicated at this time. NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 112) to step 115). No test procedures have been omitted.
31. 115) Continuous Memory Code 334: Code 334 indicates EGR valve was open with engine idling at normal operating temperature. Possible causes for this fault are: Faulty EVP sensor. Faulty EVR solenoid. Faulty EGR valve. Turn ignition off. Disconnect vacuum hose from EGR valve. Connect EGR valve hose to vacuum gauge. Start engine, and allow it to idle. Tap on EVR sensor and wiggle wiring harness while observing vacuum gauge. If vacuum gauge reading does not remain less than 1.0 in. Hg and/or has sudden vacuum increase, check for shorts in EVR solenoid connector. Repair as necessary. If connector is okay, service or replace EVR solenoid. Clear codes and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If vacuum gauge reading remains less than 1.0 in. Hg with no sudden increase, go to next step.
32. 116) EVR Solenoid Check Leave engine idling and vacuum gauge connected to EGR valve hose. Observe vacuum gauge while wiggling and bending small sections of wiring harness near EVR sensor, working from sensor toward dash panel. Wiggle and bend wiring harness from firewall to PCM. If vacuum gauge shows an increase in vacuum, isolate cause and repair as necessary. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If vacuum gauge does not show an increase in vacuum, reconnect vacuum hose to EGR valve and go to next step.
33. 117) Check EVR Signal At PCM Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect PCM to breakout box. Start engine, and allow it to idle. Connect DVOM between test pins No. 27 and 46 at breakout box. Wiggle wiring harness and lightly tap on EVP sensor. If voltage increases to more than 0.67 volt, remove and service EGR valve. If EGR valve is okay, replace EVP sensor and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If voltage is 0.67 volt or less, problem is intermittent and cannot be duplicated at this time. Testing is complete.

Perform this test when directed by QUICK TEST. This CIRCUIT TEST is intended to diagnose

1. Vehicle Speed Sensor (VSS).
2. VSS wiring harness circuits.
3. Powertrain Control Module (PCM).

Vehicle Speed Sensor Circuit. Scheme 46

TEST PIN WIRE COLOR IDENTIFICATION

Preliminary Instructions (A/T)

Record and clear continuous memory codes. Warm engine to normal operating temperature. Place gear selector in Drive position. Accelerate hard to 35 MPH and coast down to a stop. Shut off engine. Perform KOEO SELF-TEST . Go to step 1).

Preliminary Instructions (M/T)

Record and clear continuous memory codes. Warm engine to normal operating temperature. Accelerate moderately to 40 MPH. Start in first gear, shifting no higher than second gear. Decelerate to 40 MPH then shirt into third gear. Accelerate moderately to 45 MPH. Coast down to idle, and stop. Shut engine off. Perform KOEO SELF-TEST , and record continuous memory codes. Go to step 1).

1. Continuous Memory Code 452 Code 452 indicates PCM detected incorrect output from VSS sometime during vehicle operation. Possible causes for this code are: Faulty VSS. Open or shorted circuit. Faulty PCM. Perform appropriate drive cycle procedure. See «PRELIMINARY INSTRUCTIONS (A/T)»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__preliminary-instructions-at) or «PRELIMINARY INSTRUCTIONS (M/T)»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__preliminary-instructions-mt) . Ensure driveability complaint can be verified. If Code 452 is still present or driveability complaint can be verified, go to next step. If code is not present or complaint cannot be verified, fault cannot be duplicated at this time. Clear codes, and see SYMPTOMS in the «TESTS W/O CODES»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wo-codes) article.
2. Check VSS Circuit Continuity Turn ignition off. Disconnect VSS sensor. Remove PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM connector disconnected. Measure resistance between VSS (+) terminal at VSS wiring harness connector and test pin No. 3 at breakout box. Also, measure resistance between VSS (-) terminal at VSS wiring harness connector and test pin No. 6 at breakout box. If any resistance reading is more than 5 ohms, repair open circuit in VSS wiring harness. Remove breakout box reconnect all components. Repeat step 1). If both resistance readings are 5 ohms or less, go to next step.
3. Check VSS Circuits For Shorts To Power Or Ground Turn ignition off. Ensure PCM and VSS are disconnected. Measure resistance between test pin No. 3 and test pins No. 6, 37 and 40 at breakout box. If all readings are more than 500 ohms, go to next step. If any reading is 500 ohms or less, repair shorts in VSS wiring harness and repeat step 1).
4. Check VSS Resistance Turn ignition off. Disconnect VSS wiring harness connector. Measure resistance between VSS terminals. If resistance is not 190-250 ohms, replace VSS and repeat step 1). If resistance is 190-250 ohms, replace PCM and repeat step 1).

CID signal provides PCM information for fuel injector synchronization. The CID signal originates from Camshaft Position (CMP) sensor.

Enter this CIRCUIT TEST only when instructed during QUICK TEST. This test is only intended to diagnose

Scheme 47

1. CID +, CID -, CID, SIG RTN and VREF wiring harness circuits.
2. Camshaft Position (CMP) sensor.
3. Crankshaft Position (CKP) sensor.
4. Powertrain Control Module (PCM). (Scheme 47): CID Wiring Harness Circuits TEST PIN WIRE COLOR ID Application Wire Color TEST PIN NO. 24 (CID) Dark Blue/Orange TEST PIN NO. 46 (SIG RTN) Gray/Red

1. 1) Continuous Memory Code 214 Code 214 indicates error has been detected in CID sensor input signal. Error could be due to a hard fault or an intermittent fault. Possible causes for this fault are: Open or shorted wiring harness. Faulty CMP sensor. Faulty ICM. Faulty PCM. Start engine. If engine starts, go to next step. If engine does not start, go to IGNITION SYSTEMS in the «SYSTEM/COMPONENT TESTS»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-46l) article.
2. 2) Attempt To Generate Code 214 Clear continuous memory codes. Start engine. Raise engine speed to 1500 RPM for 10 seconds. Return to idle speed. Raise speed to 1500 RPM for 10 seconds again. Turn ignition off. Perform «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) . If Continuous Memory Code 214 is not present, go to step 20). If Continuous Memory Code 214 is present, go to next step.
3. 3) Check Continuity Of CID Circuits Disconnect CMP sensor. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure and record resistance between CID or CID (+) test pin at breakout box and CID or CID (+) terminal at sensor wiring harness connector. Also, measure resistance between test pin No. 46 and SIG RTN circuit at CMP sensor wiring harness connector. If any resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If each resistance is less than 5 ohms, go to next step.
4. 4) Check CID Circuit For Short To Power Turn ignition off. Ensure PCM and CMP sensor are disconnected. Ensure scan tester is not connected to vehicle. Turn ignition on. Measure voltage between CID or CID (+) test pin and test pin No. 40 at breakout box. If voltage is less than 1.0 volt, go to next step. If voltage is 1.0 volt or more, repair short to power in CID circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
5. 5) Check CID Circuit For Short To Ground Turn ignition off. Ensure PCM and CMP sensor are disconnected. Measure resistance between CID or CID (+) test pin and pins No. 16, 40 and 46 at breakout box. If any reading is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If all readings are more than 10,000 ohms, go to step 7).
6. 6) Check VPWR Circuit Voltage Ensure PCM and CMP are disconnected. Turn ignition on. Measure voltage between VPWR terminal at CMP sensor and negative battery terminal. If voltage is less than 10.5 volts, repair open in VREF circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If voltage is 10.5 volts or more, go to next step.
7. 7) Check For Shorts In PCM Turn ignition off. Ensure CMP is disconnected. Connect PCM to breakout box. Measure resistance between test pin No. 24 and test pins No. 16, 37, 40, 46, 57 and 60 at breakout box. If all readings are more than 500 ohms, go to next step. If any reading is 500 ohms or less, replace PCM. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
8. 8) Check CMP Sensor Output Turn ignition off. Reconnect CMP sensor wiring harness connector. Set DVOM on AC scale. Start engine. Measure voltage between test pins No. 24 and 40 while varying engine RPM. If voltage varies more than 0.1 volt, replace PCM. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If voltage does not vary more than 0.1 volt, replace CMP sensor. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 8) to step 10). No test procedures have been omitted.
9. 10) Check VPWR At CMP Sensor Turn ignition off. Disconnect CMP sensor. Turn ignition on. Measure voltage between VPWR terminal at CMP sensor wiring harness connector and negative battery terminal. If voltage is less than 10.5 volts, repair open in VREF circuit and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If voltage is 10.5 volts or more, VPWR circuit is okay.Go to IGNITION SYSTEMS in the «SYSTEM/COMPONENT TESTS»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-46l) article. NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 10) to step 20). No test procedures have been omitted.
10. 20) Check CID Circuit Enter wiggle test. See «CONTINUOUS MONITOR MODE (WIGGLE TEST)»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__continuous-monitor-mode-wiggle-test) under QUICK TEST. Observe analog VOM or diagnostic tester for indication of fault while performing following: grasp wiring harness near PCM wiring harness connector while observing VOM or diagnostic tester for fault indication. Shake and bend small sections of harness, working from PCM toward sensor. If fault is indicated, isolate fault and repair as necessary. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If no fault is indicated, problem cannot be duplicated at this time. See SYMPTOMS in the «TESTS W/O CODES»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wo-codes) article.

Perform this test when directed by QUICK TEST or other test procedures. This test is intended to diagnose the following

Scheme 48

1. PSP sensor.
2. PSP, SIG RTN and VREF wiring harness circuits.
3. Powertrain Control Module (PCM). (Scheme 48): PSP Sensor Circuit

1. Verify Operator Interaction Code 519 indicates PSP sensor circuit is open. Code 521 indicates a PSP sensor signal malfunction. Possible causes for this fault are: Damaged PSP sensor. Open or shorted SIG RTN circuit. Open or shorted VREF circuit. Open or shorted PSP sensor signal circuit. Faulty Powertrain Control Module (PCM). If Code 519 is present, go to next step. If Code 519 is not present, during KOER SELF-TEST, ensure steering wheel was turned at least 1/2 turn within 1-2 seconds after ID portion of test. If steering wheel was turned, go to next step. If steering wheel was not turned, repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
2. Check VREF Circuit Voltage Turn ignition off. Disconnect PSP sensor connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Turn ignition on. Measure voltage between VREF circuit terminal (Brown/White wire) and SIG RTN circuit terminal (Yellow/White wire) at PSP sensor wiring harness connector. If voltage is 4-6 volts, go to next step. If voltage is not 4-6 volts, go to «CIRCUIT TEST C»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
3. Check PCM Response Start engine and allow it to idle. Connect a jumper wire between VREF circuit terminal and PSP sensor circuit terminal at PSP sensor wiring harness connector. If engine speed increased, reconnect PSP sensor connector and go to next step. If engine speed did not increase, go to step 5).
4. Check PSP Sensor Operation Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM connected. Start engine and allow it to idle. Connect voltmeter between test pins No. 28 and 46 at breakout box. Observe voltmeter and turn steering wheel all the way to the left then all the way to the right. If voltage changes from 0.5-4.5 volts, PSP circuit is functioning properly. Fault is intermittent and cannot be duplicated at this time. Testing is complete. If voltage does not change from 0.5-4.5 volts, replace PSP sensor. Remove breakout box, reconnect all components and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
5. Check PSP Sensor Circuit Continuity Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM connected. Ensure PSP sensor is disconnected. Perform the following procedures. Measure resistance between PSP sensor signal circuit terminal (White/Violet wire) at PSP sensor wiring harness connector and test pin No. 28 at breakout box. Measure resistance between VREF circuit terminal (Black/White wire) at PSP sensor wiring harness connector and test pin No. 26 at breakout box. Measure resistance between SIG RTN sensor signal circuit (Yellow/White wire) at PSP sensor wiring harness connector and test pin No. 46 at breakout box. If each reading is less than 5 ohms, go to next step. If any reading is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
6. Check For Short To Power Or Ground In PSP Sensor Signal Circuit Measure resistance between test pin No. 28 and test pins No. 26 and 46 at breakout box. Also measure resistance between test pin No. 28 and test pins No. 40, 46 and 60 at breakout box. If each reading is more than 10,000 ohms, replace PCM. Remove breakout box, reconnect all components and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If any reading is 10,000 ohms or less, repair short to power or short to ground. Remove breakout box, reconnect all components and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .

Perform this test when directed by QUICK TEST. This test is intended to diagnose a faulty BOO switch circuit or PCM. To prevent replacement of good components, be aware following non-EEC related areas may be at fault

Scheme 49

1. Brakelight bulb.
2. Brakelight switch or brakelight fuse. (Scheme 49): BOO Switch Circuit TEST PIN NO. 2 OR 5 (BOO) WIRE COLOR ID Application Test Pin No. Wire Color Mark VIII 2 Light Green

1. 1) Code 536: Verify Brake Pedal Was Depressed Code 536 indicates that when brake pedal is applied and released during KOER SELF-TEST, BOO signal did not cycle high and low. Possible causes for this fault are: Brake pedal not applied and released during self-test. Brake pedal applied during entire self-test. Open brakelight circuit. Short to ground or power. Faulty brakelight switch. Faulty Powertrain Control Module (PCM). If brake was not applied during KOER SELF-TEST, repeat test. Depress and release brake pedal only once during test. If pedal was depressed, go to next step.
2. 2) Check Operation Of Brakelights With ignition on, check operation of brakelights. If brakelights operate normally, go to next step. If brakelights do not operate, go to step 4). If brakelights are always on,go to step 5).
3. 3) Check For BOO Switch Circuit Cycling Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure voltage between BOO test pin (No. 2 or 5) and test pin No. 40 while applying and releasing brake. If voltage cycles, replace PCM and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If voltage does not cycle, repair open circuit in BOO switch circuit between PCM and BOO switch connection to brakelight circuit. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
4. 4) Check For Power To Brakelight Switch Ensure related fuses and brakelight bulbs are in good condition. Turn ignition off. Disconnect brakelight switch (located on brake pedal). Measure voltage between BATT (+) input to brakelight switch and ground. If voltage is more than 10 volts, check condition of brakelight switch. If brakelight switch is okay, repair open circuit between brakelight switch and brakelight ground. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If voltage is less than 10 volts, repair open BATT (+) circuit to brakelight switch and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
5. 5) Verify Brake Switch Is Not Always Closed Turn ignition off. Disconnect brakelight switch (located on brake pedal). Turn ignition on. If brakelights are still on, go to next step. If brakelights are not on, verify correct installation of brakelight switch. If installation is okay, replace brakelight switch and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
6. 6) Check For Short To Power In PCM Turn ignition off. Disconnect PCM. Turn ignition on. Check brakelights. If brakelights are on, go to next step. If brakelights are off, replace PCM and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
7. 7) Check For Short To Power In Shift Lock Actuator Turn ignition off. Ensure PCM and brakelight switch are disconnected. Disconnect shift lock actuator, cruise control module and ABS module (if equipped). Turn ignition on. If brakelights are still on, repair short to power in BOO or STOP LAMP circuit and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If brakelights are off, repair short circuit in shift lock actuator circuit, cruise control system circuit or ABS circuit. Reconnect all components and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 7) to step 90). No test procedures have been omitted.
8. 90) Continuous Memory Code 536: Check For Proper Brakelight Switch Installation Code 536 indicates a BOO circuit failure. Possible causes for this fault are: Brakelight switch installed improperly. Open brakelight circuit. Short to ground or power. Faulty brakelight switch. Faulty brakelight switch ground connection. Check brakelight switch for proper installation (alignment with brake pedal, corrosion or frayed wires). If brakelight switch is okay, go to next step. If brakelight switch is not okay, repair as necessary. Clear codes and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
9. 91) Check Brakelight Switch Ground Check brakelight switch ground connection. Also, check brakelight connector wires for corrosion or damage. Repair as necessary. Clear codes and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If connector and wires are okay, go to next step.
10. 92) Check Brakelight BOO Circuits For Short To Power Turn ignition on. Observe brakelights. With brake pedal released, wiggle brakelight BOO circuit wires and connectors. If brakelights flash, isolate short to power and repair as necessary. Clear codes and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If brakelights do not flash, go to next step.
11. 93) Check Brakelight Circuit Continuity Turn ignition off. Depress and hold-down brake pedal. Observe brakelights and wiggle brakelight circuit wires and connectors. Also, lightly tap on brakelight switch (to simulate road shock). If brakelights flash or go off, isolate open in brakelight circuit and repair as necessary. Clear codes and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If brakelights stay on (normal operation), go to next step.
12. 94) Check BOO Circuit Continuity Turn ignition off. Release brake pedal. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Connect DVOM between BOO test pin (No. 2 or 5) at breakout box and BOO terminal at brakelight switch. Observe DVOM and wiggle BOO circuit wires and connectors. If resistance at anytime was more than 5 ohms, isolate open in BOO circuit and repair as necessary. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If resistance was 5 ohms or less at all times, fault is intermittent and cannot be duplicated at this time. Testing is complete.

Electrical load inputs are used for idle speed control strategy so correct idle can be maintained regardless of electrical demands on engine. PCM uses 4 accessories to determine electrical load status: blower motor, headlights, rear window defroster, and daytime running lights (if equipped).

Perform this test when directed by QUICK TEST, CIRCUIT TEST S or if directed by other test procedures. This CIRCUIT TEST is intended to diagnose

1. Blower (BLR) motor input circuit.
2. Daytime Running Lights (DRL) input circuit.
3. Headlight (HDL) input circuit.
4. Rear window Defroster (DEF) input circuit.
5. Powertrain Control Module (PCM). SWITCH CIRCUIT LOGIC Application Switch Position Voltage Blower Motor 1 Or 2 10-17 Blower Motor 3 Or 4 Less Than 1.5 Daytime Running Lights Off 10-17 Daytime Running Lights On Less Than 1.5 Headlights Off Less Than 1.5 Headlights On 10-17 Rear Window Defroster Off 10-17 Rear Window Defroster On Less Than 3.0

1. 1) Isolate Faulty System If idle speed fault occurs when blower motor is on, go to step 10). If idle speed fault occurs when daytime running lights are on, go to step 20). If idle speed fault occurs when headlights are on, go to step 30). If idle speed fault occurs when rear window defroster is on, go to step 40). NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 1) to step 10). No test procedures have been omitted.
2. 10) Check Blower Motor Switch (Low Speed) Turn ignition and all accessories off. Remove PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Turn ignition on. Turn climate control motor switch to low-speed position "1" or "2". Measure voltage between chassis ground and test pin No. 29 at breakout box. If voltage is not 10-17 volts, go to step 13). If voltage is 10-17 volts, go to next step.
3. 11) Check Blower Motor Switch (High Speed) Turn ignition and all accessories off. Turn climate control motor switch to high-speed position "3" or "4". Turn ignition on. Measure voltage between chassis ground and test pin No. 29 at breakout box. If voltage is less than 1.5 volts, replace PCM and confirm idle speed fault has been corrected. If voltage is 1.5 volts or more, go to next step.
4. 12) Check Blower Circuit For Short To Power Turn ignition off. Disconnect high speed blower motor relay connector. Relay is located behind right side of instrument panel on blower assembly. Measure resistance between test pin No. 29 and test pins No. 37 and 57 at breakout box. If all readings are more than 10,000 ohms, check for damaged blower motor switch or relay. If any reading is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and confirm idle speed fault has been corrected.
5. 13) Check Blower Circuit Continuity Turn ignition off. Disconnect blower high speed blower motor relay. Measure resistance between BLR terminal (Orange/Black wire) at high speed blower motor relay connector and test pin No. 29 at breakout box. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and confirm idle speed fault has been corrected. If resistance is less than 5 ohms, go to next step.
6. 14) Check Blower Circuit For Short To Ground Turn ignition off. Disconnect high speed blower motor relay. Measure resistance between test pin No. 29 and test pins No. 40, 46 and 60 at breakout box. If all readings are more than 10,000 ohms, check for damaged blower motor switch or relay. If any reading is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and confirm idle speed fault has been corrected. NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 14) to step 20). No test procedures have been omitted.
7. 20) Check DRL Circuit Voltage (Headlights On) Turn ignition. Remove PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Apply parking brake. Turn ignition on. Turn headlights on. Turn accessories off. Measure voltage between chassis ground and test pin No. 14 at breakout box. If voltage is not 10-17 volts, go to step 23). If voltage is 10-17 volts, go to next step.
8. 21) Check DRL Circuit Voltage (Headlights Off) Turn headlights off. Release parking brake. Turn ignition on. Measure voltage between chassis ground and test pin No. 14 at breakout box. If voltage is less than 1.5 volts, replace PCM. Remove breakout box and confirm idle speed fault has been corrected. If voltage is 1.5 volts or more, go to next step.
9. 22) Check DRL Circuit For Short To Power Turn ignition off. Ensure PCM is disconnected. Disconnect daytime running lights relay. Measure resistance between test pin No. 14 and test pins No. 37 and 57 at breakout box. If all readings are more than 10,000 ohms, check daytime running lights module for malfunction. If any reading is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and confirm idle speed fault has been corrected.
10. 23) Check DRL Circuit Continuity Turn ignition off. Disconnect daytime running lights relay. Measure resistance between DRL circuit terminal at DRL wiring harness connector and test pin No. 14 at breakout box. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and confirm idle speed fault has been corrected. If resistance is less than 5 ohms, go to next step.
11. 24) Check DRL Circuit For Short To Ground Turn ignition off. Measure resistance between test pin No. 14 and test pins No. 40, 46 and 60 at breakout box. If all readings are more than 10,000 ohms, check daytime running lights module for malfunction. If any reading is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and confirm idle speed fault has been corrected. NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 24) to step 30). No test procedures have been omitted.
12. 30) Check Headlight Circuit Voltage (Headlights Off) Turn ignition off. Remove PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Turn all accessories off. Turn ignition on. Measure voltage between chassis ground and test pin No. 42 at breakout box. If voltage is 1.5 volts or more, go to step 34). If voltage is less than 1.5 volts, go to next step.
13. 31) Check Headlight Circuit Voltage (Headlights On) Turn all accessories off. Turn ignition on. Turn headlights on. Measure voltage between chassis ground and test pin No. 42 at breakout box. If voltage is 10-17 volts, replace PCM. Remove breakout box and confirm idle speed fault has been corrected. If voltage is not 10-17 volts, go to next step.
14. 32) Check HDL Circuit Continuity Turn ignition off. Disconnect headlight relay. Relay is located in engine compartment relay box. Measure resistance between HDL circuit terminal (White wire) at headlight relay connector and test pin No. 42 at breakout box. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and confirm idle speed fault has been corrected. If resistance is less than 5 ohms, go to next step.
15. 33) Check HDL Circuit For Short To Ground Turn ignition off. Disconnect headlight relay. Measure resistance between test pin No. 42 and test pins No. 40, 46 and 60 at breakout box. If all readings are more than 10,000 ohms, check headlight switch for malfunction. If any reading is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and confirm idle speed fault has been corrected.
16. 34) Check HDL Circuit For Short To Power Turn ignition off. Disconnect headlight relay. Measure resistance between test pin No. 42 and test pins No. 37 and 57 at breakout box. If all readings are more than 10,000 ohms, check headlight switch for malfunction. If any reading is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and confirm idle speed fault has been corrected. NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 34) to step 40). No test procedures have been omitted.
17. 40) Check DEF Circuit Voltage (Defrost Off) Turn ignition off. Turn all accessories off. Remove PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Turn ignition on. Measure voltage between chassis ground and test pin No. 23 at breakout box. If voltage is 10-17 volts, go to next step. If voltage is not 10-17 volts, go to step 43).
18. 41) Check DEF Circuit Voltage (Defrost On) Turn ignition on. Turn rear window defroster on. Measure voltage between chassis ground and test pin No. 23 at breakout box. If voltage is less than 3 volts, replace PCM. Remove breakout box and confirm idle speed fault has been corrected. If voltage is 3 volts or more, go to next step.
19. 42) Check DEF Circuit For Short To Power Turn ignition off. Disconnect rear window defroster relay. Relay is located in left side of trunk. Measure resistance between test pin No. 23 and test pins No. 37 and 57 at breakout box. If all readings are more than 10,000 ohms, check DEF switch or relay for malfunction. If any reading is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and confirm idle speed fault has been corrected.
20. 43) Check DEF Circuit Continuity Turn ignition off. Disconnect rear window defroster switch. Measure resistance between DEF circuit terminal (Pink/Black wire) at defroster relay wiring harness connector and test pin No. 23 at breakout box. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and confirm idle speed fault has been corrected.
21. 44) Check DEF Circuit For Short To Ground Turn ignition off. Disconnect rear window defroster relay. Measure resistance between test pin No. 23 and test pins No. 40, 46 and 60 at breakout box. If all readings are more than 10,000 ohms, check DEF switch and relay circuit for malfunction. If any reading is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and confirm idle speed fault has been corrected.

The PSP switch is a normally closed switch that opens as pressure in the power steering system increases. Perform this test when instructed during QUICK TEST or if directed by other test procedures. Some vehicles may not have power steering, but PCM may be equipped with PSP switch software strategy. If a KOEO Code 519 is displayed, check if vehicle is equipped with power steering. If vehicle is not equipped with power steering, disregard Code 519. This test is only intended to diagnose

1. Power Steering Pressure (PSP) switch.
2. PSP and SIG RTN wiring harness circuits.
3. Powertrain Control Module (PCM).

To prevent replacement of good components, be aware the following non-EEC related areas may be at fault

Scheme 50

1. Idle speed/throttle stop adjustment.
2. Binding throttle shaft/linkage.
3. Cruise control linkage.
4. Power steering hydraulic system. (Scheme 50): Power Steering Pressure (PSP) Switch Circuit PSP SWITCH BREAKOUT BOX TEST PIN NUMBER ID Application Test Pin No. Wire Color Mark VIII 28 Yellow/Light Green

1. 1) KOEO Code 519: Attempt To Eliminate Code Code 519 indicates PSP switch circuit is open. Possible causes for this fault are: Damaged PSP switch. Open circuit in wiring harness. Faulty PCM. Turn ignition off. Disconnect PSP switch. Connect a jumper wire between PSP circuit terminal and SIG RTN terminal at PSP wiring harness connector. Repeat «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) . If Code 519 is not displayed, replace PSP switch and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If Code 519 is displayed, remove jumper wire and go to next step.
2. 2) Check Continuity Of PSP Circuits Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pin No. 46 at breakout box and SIG RTN terminal at PSP switch wiring harness connector. Measure resistance between PSP test pin at breakout box and PSP circuit terminal at PSP switch wiring harness connector. If all readings are less than 5 ohms, replace PCM. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If any reading is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
3. 3) Check PSP Switch Operation Turn ignition off. Connect tachometer, and start engine. Allow engine to idle in Park or Neutral. Disconnect PSP switch wiring harness connector. If RPM increases, replace PSP switch and recheck system. If RPM does not increase, go to next step.
4. 4) Check PSP Switch Circuits For Shorts Turn ignition off. Disconnect PSP switch wiring harness connector. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between PSP test pin and test pin No. 46 at breakout box. If resistance is 10,000 ohms or less, repair short in wiring harness and recheck symptom. If resistance is more than 10,000 ohms, replace PCM and recheck symptom.
5. 5) KOER Code 521 Disregard this code if vehicle does not have power steering. Code 521 indicates PSP switch did not change states due to open or closed switch. Possible causes for this fault are: Damaged PSP switch. Open or shorted circuit in wiring harness. Front wheels turned but not centered. Faulty PCM. If steering wheel was turned at least 1/2 turn within 2 seconds after engine ID code and then returned to center, go to next step. If steering wheel was not turned, repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
6. 6) Check PCM Open Circuit Identifying Capabilities Turn ignition off. Disconnect PSP switch. Perform «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) . If Code 519 is present, go to step 8). If Code 519 is not present, go to next step.
7. 7) Check PSP Switch Circuits For Shorts Turn ignition off. Disconnect PSP switch. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between PSP test pin and test pin No. 46 at breakout box. If resistance is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If resistance is more than 10,000 ohms, replace PCM. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
8. 8) Check PSP Switch Position Comparison Turn ignition off. Connect PCM connector to breakout box. With PSP switch connected, turn ignition on. Measure and record resistance between PSP test pin and test pin No. 46 at breakout box. Observe voltmeter and start engine. If reading shows less than 10 ohms difference between key on engine off and key on engine running, go to next step. If reading is not as specified, replace PSP switch and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
9. 9) Check PSP Switch With Engine Running (Load & No Load) Connect PSP switch. Start engine, and allow it to idle. Measure resistance between PSP test pin and test pin No. 46 at breakout box. Turn steering wheel 1/2 turn and return to center position. If resistance changes from less than 10 ohms to infinity and then returns to 10 ohms or less (when steering wheel is centered), PSP switch system is okay. Testing is complete. If reading does not change as indicated, replace PSP switch. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
10. 10) Code 519: Attempt To Eliminate Code 519 Disregard this code if vehicle does not have power steering. Code 519 indicates PSP switch circuit is closed. Possible causes for this fault are: Damaged PSP switch. Open or shorted circuit in wiring harness. Faulty PCM. Turn ignition off. Disconnect PSP switch connector. Repeat «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) . If Code 519 is not present, replace PSP switch. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If Code 519 is present, go to next step.
11. 11) Check PSP Circuit For Short Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between PSP test pin and test pin No. 46 at breakout box. If reading is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and recheck symptom. If reading is more than 10,000 ohms, replace PCM. Remove breakout box, reconnect all components, and recheck symptom. NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 11) to step 15). No test procedures have been omitted.
12. 15) Check PSP Switch Operation Connect tachometer, and start engine. Allow engine to idle in Park or Neutral. Disconnect PSP switch connector. Connect a jumper wire between ground and PSP circuit terminal at PSP switch wiring harness connector. If RPM increases, replace PSP switch and recheck symptom. If RPM does not increase, go to next step.
13. 16) Check Continuity Of PSP Switch Circuits Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM connected. Measure resistance between PSP switch test pin at breakout box and PSP circuit terminal at PSP switch wiring harness connector. Measure resistance between SIG RTN circuit terminal at PSP switch wiring harness connector and test pin No. 46 at breakout box. If all readings are less than 5 ohms, replace PCM. Remove breakout box, reconnect all components, and recheck symptom. If any reading is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 16) to step 20). No test procedures have been omitted.
14. 20) KOER Code 521 Disregard this code if vehicle does not have power steering. Code 521 indicates PSP switch did not change states due to open or closed switch. Possible causes for this fault are: Damaged PSP switch. Open or shorted circuit in wiring harness. Front wheels turned but not centered. Faulty PCM. If steering wheel was turned 1/2 turn within 2 seconds after engine ID code and then returned to center, go to next step. If steering wheel was not turned, repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
15. 21) Check PCM Closed Circuit Identifying Capabilities Turn ignition off. Disconnect PSP switch. Connect jumper wire between ground and PSP circuit terminal at PSP switch wiring harness connector. Perform «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) . If Code 519 is present, remove jumper wire and go to step 23). If Code 519 is not present, go to next step.
16. 22) Check Continuity Of PSP Switch Circuits Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between PSP test pin at breakout box and PSP circuit terminal at PSP switch wiring harness connector. Measure resistance between test pin No. 46 at breakout box and SIG RTN terminal at PSP switch wiring harness connector. If all readings are less than 5 ohms, replace PCM and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If any reading is 5 ohms or more, repair open circuit and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
17. 23) Check PSP Switch Position Comparison Turn ignition off. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM connected. Reconnect PSP switch. Turn ignition on. Measure resistance between PSP switch test pin and test pin No. 46 at breakout box. Start engine. If reading remains less than 10 ohms difference between key on engine off and key on engine running, go to next step. If reading is not as specified, replace PSP switch and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
18. 24) Check PSP Switch With Engine Running (Load & No Load) Start engine, and allow it to idle. Measure resistance between PSP switch test pin and test pin No. 46 at breakout box. Turn steering wheel 1/2 turn and return to center position. If resistance changes from less than 30 ohms to infinity and then returns to 30 ohms or less (when steering wheel is centered), PSP switch system is okay. Testing is complete. If reading does not change as indicated, replace PSP switch. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .

Perform this test when instructed during QUICK TEST or if directed by other test procedures. To prevent replacement of good components, be aware the following non-EEC related areas may be at fault

1. Excessive blow-by.
2. PCV malfunction.
3. Vacuum leaks.
4. Incorrect fuel pressure.
5. Throttle binding.
6. Improper fuel pressure.
7. Idle air control solenoid.

This test is only intended to diagnose

1. MAP/BARO sensor.
2. Throttle Position (TP) sensor.
3. Mass Airflow (MAF) sensor.
4. Intake Air Temperature (IAT) sensor.
5. Fuel injectors.

1. Check For Idle Air Codes Code 121 indicates TP sensor is inconsistent with MAF value. Code 124 indicates TP sensor value is higher than expected. Code 125 indicates TP sensor value is lower than expected. Turn ignition on. Repeat «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) . If Code 411 or 412 is present, perform appropriate circuit test. See «DIAGNOSTIC TROUBLE CODE REFERENCE CHARTS»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If Code 411 or 412 is not present, go to next step.
2. Throttle Position (TP) Sensor: TP Sensor Integrity Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect PCM to breakout box. Connect DVOM to test pins No. 46 and 47 at breakout box. Turn ignition on. Slowly apply throttle to WOT, and release to closed position. Voltage should change smoothly from 0.4-4.5 volts. See «CIRCUIT TEST DH»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) for schematics and TP sensor specifications. If voltage change is incorrect or erratic, ensure TP sensor is properly installed. If TP sensor is properly installed, replace TP sensor. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If voltage is okay and Code 121 is present, go to step 8). If voltage is okay and Code 121 is not present, go to next step.
3. Check Idle Ensure idle is correct. If idle is correct, go to next step. If idle is incorrect, see IDLE SPEED in the «ADJUSTMENTS»(ref-23158) article.
4. Check Throttle Body Ensure idle is correct. Check throttle and/or cruise control linkage for binding and rough operation. Inspect throttle body for sludge build-up. Check engine vacuum hoses. Refer to Vehicle Emission Control Information (VECI) decal for proper vacuum hose routing. Check for air leak between IAC solenoid and MAF sensor. If problems are found, repair as necessary. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If no problems are found, go to next step.
5. Check MAP/BARO Sensor Output On vehicles without MAP/BARO go to next step. On vehicles with MAP/BARO, see «DIAGNOSTIC AIDS»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) , then continue with this test. With tester connected and ignition on, measure sensor output voltage. If output voltage is within range for specified altitude, remove MAP/BARO tester and go to next step. See «MAP SENSOR VOLTAGE OUTPUT»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) table for specification. If output voltage is not within range, replace MAP/BARO sensor. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . MAP SENSOR VOLTAGE OUTPUT Elevation (Feet) Volts 0 1.55-1.63 1000 1.52-1.60 2000 1.49-1.57 3000 1.46-1.54 4000 1.43-1.51 5000 1.40-1.48 6000 1.37-1.45 7000 1.35-1.43
6. Check IAT Sensor Ensure ambient temperature is more than 50°F (10°C) before performing this test. Also, check and repair any air leaks in front of IAT sensor. Turn ignition off. Connect breakout box to PCM. Set DVOM to 20-volt scale. Connect DVOM to test pins No. 25 and 46. Start engine, and let it idle. Observe voltage as engine warms up. See «CIRCUIT TEST DA»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) for voltage specifications. If voltage decreases smoothly and stabilizes when engine reaches operating conditions, system is operating properly at this time. Testing is complete. If voltage does not decrease smoothly and stabilize after engine reaches operating conditions, replace IAT sensor and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
7. Continuous Memory Code 184 & 185: Inspect MAF Sensor Code 184 indicates MAF sensor signal is higher than expected. Code 185 indicates MAF sensor signal is lower than expected. Turn ignition off. Check for air leaks between Idle Air Control (IAC) solenoid and MAF sensor. Inspect MAF sensor for oil contamination caused by excessive blow-by or malfunctioning PCV. If problems are found, repair as necessary. Clear codes and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If no problems are found, go to step 10).
8. Check MAF Sensor Circuit Voltage Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect PCM to breakout box. Start engine, and warm it to normal operating temperature. Measure voltage between test pin No. 50 and test pin No. 40 or 60 at breakout box. If voltage is not within specification, replace MAF sensor. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . For MAF sensor specifications, see the appropriate «PIN VOLTAGE CHARTS»(ref-23254) article. If voltage is within acceptable range, system is operating normally at this time. Sometime during the last 80 warm-up cycles, MAF sensor signal was out of range.
9. Continuous Memory Code 186 & 187: Visual Vacuum Checks Code 186 indicates pulse width is longer than expected (rich). Code 187 indicates pulse width is shorter than expected (lean). Inspect air cleaner and air inlet duct. Replace or repair an necessary. Check for unmetered air leaks between MAF sensor and IAC solenoid. Check all engine vacuum hoses for damage, blockage and improper routing. Repair a necessary, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If all checks are okay, go to next step.
10. Check Fuel Pressure Turn ignition off. Install fuel pressure gauge. Ensure vacuum hose is connected to fuel pressure regulator (if applicable). Start engine, and run it at idle. For fuel pressure specifications, see «FUEL PRESSURE SPECIFICATIONS»(/lincoln/mark-viii/i-1992-1998/remont/specifications/#fuel-pressure-specifications) article. If fuel pressure is within specification, go to next step. If fuel pressure is not within specification, repair as necessary. See FUEL SYSTEM in the «SYSTEM/COMPONENT TESTS»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-46l) article.
11. Verify Fuel Pressure Retention Ability Turn ignition on. If fuel pressure remains at specification for 60 seconds, go to next step. If fuel pressure does not remain at specification, repair fuel delivery system as necessary. See FUEL SYSTEM in the «SYSTEM/COMPONENT TESTS»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-46l) article.
12. Cylinder Balance Test Perform «KOER SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . After last code, wait 5-10 seconds, and then goose throttle lightly (not wide open throttle). This will activate cylinder balance test. If Code 90 is present after test, go back to step 7). If Code 90 is not present after test, go to «CIRCUIT TEST H»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__circuit-test-h-fuel-control) , step 4).

If possible, measure several known good MAP/BARO sensors. Average voltage reading will be typical for location and day of testing. Also, refer to CIRCUIT TEST DF for MAP/BARO sensor output check. (Scheme 38)for connector terminal identification and MAP/BARO tester hookup.

CIRCUIT TEST H - FUEL CONTROL

Note. For fuel pressure specifications, see FUEL PRESSURE SPECIFICATIONS article.

Perform this test when instructed during QUICK TEST or if directed by other test procedures. (Fuel-contaminated engine oil may affect Codes 136, 137, 139, 144, 171, 172, 173, 175, 176 and 177. If fuel-contaminated engine oil is suspected, remove PCV valve from valve cover and repeat QUICK TEST ). If problem is corrected, change engine oil and filter. Only use this test to diagnose

1. HO2S and sensor connection.
2. Vacuum systems.
3. Fuel injector and/or fuel injector circuitry.
4. Powertrain Control Module (PCM).
5. Electrical circuits (HO2S, HO2S GND, INJ 1-8, VPWR and SIG RTN).

To prevent replacement of good components, be aware the following non-EEC areas may be cause of driveability concerns

Scheme 51

1. Ignition system.
2. Faulty evaporative emission system.
3. EGR and/or PCV system.
4. Air intake system.
5. Engine oil contamination.
6. Fuel system.
7. Intake, supercharger, or charge air cooler leaks.
8. Exhaust system leaks or restriction.
9. Electrical system.
10. Secondary air injection system.
11. Engine cooling system. (Scheme 51): Identifying Fuel Injector & HO2S Connector Terminals INDIVIDUAL INJECTOR RESISTANCE Engine Ohms Mark VIII 11-18 TEST PIN WIRE COLOR ID Application Test Pin No. Wire Color HO2S-1 44 Gray/Light Blue HO2S-2 43 Red/Black HO2S-GROUND 46 Gray/Red FUEL INJECTOR TEST PIN NO. IDENTIFICATION Application Test Pin No. Wire Color Cylinder No. 1 58 Tan Cylinder No. 2 59 White Cylinder No. 3 39 Brown/Yellow Cylinder No. 4 35 Brown/Light Blue Cylinder No. 5 15 Tan/Black Cylinder No. 6 12 Light Green/Orange Cylinder No. 7 13 Tan/Red Cylinder No. 8 14 Light Blue TEST PIN NO. 37/57 (VPWR) WIRE COLOR IDENTIFICATION Application Wire Color Mark VIII Red

Scheme 52

1. 1) Check For Contaminated Engine Oil Turn ignition off. Remove PCV valve from valve cover. Inspect PCV system for damage. Inspect valve for blockage and movement of valve plunger. Repair as necessary. Perform «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) and «KOER SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). Service ignition continuous memory code (if present) before servicing KOER codes. If vehicle is a no-start, install PCV valve and go to next step. If Code 139, 144, 171, 176 or 177 is present, go to next step. If no codes are set, change engine oil and filter. Install PCV valve, and drive vehicle for 5 miles at 55 MPH. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
2. 2) Check Fuel Pressure Turn ignition off. Release fuel pressure. Install fuel pressure gauge. Ensure manifold vacuum supply is connected to fuel pressure regulator (if equipped). Run engine at idle and check fuel pressure. If vehicle will not start, cycle ignition on and off several times. Check fuel pressure. For fuel pressure specifications, see «FUEL PRESSURE SPECIFICATIONS»(/lincoln/mark-viii/i-1992-1998/remont/specifications/#fuel-pressure-specifications) article. If fuel pressure is within specification, go to next step. If pressure is not within specification, repair fuel system as necessary. See FUEL SYSTEM in the «SYSTEM/COMPONENT TESTS»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-46l) article.
3. 3) Check System Ability To Hold Fuel Pressure Turn ignition on. Check fuel system for leaks. Repair or replace as necessary. If fuel system does not leak and pressure remains at specification for 60 seconds, go to next step (no-starts) or step 6) (all others).
4. 4) Fuel Delivery Test Release fuel system pressure. With fuel pressure gauge installed, pressurize fuel system as in step 1). Disconnect inertia switch. Crank engine for 5 seconds. If fuel pressure drop is greater than 5 psi after 5 seconds of cranking, EEC-IV system is not causing no-start condition. Check additional no-start tests in the appropriate «TESTS W/O CODES»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wo-codes) article. If fuel pressure drop is less than 5 psi, remove fuel pressure gauge. Connect inertia switch and go to step 8). NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 4) to step 6). No test procedures have been omitted.
5. 6) Cylinder Balance Test (SFI) Perform «KOER SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). After last code is displayed, wait 5-10 seconds. Enter CYLINDER BALANCE TEST by lightly goosing throttle (not WOT). Test time is about 2-3 minutes. To interpret codes retrieved from test, refer to «CYLINDER BALANCE TEST SERVICE CODES»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) table. If fault codes are present, go to step 8). Code 538 indicates throttle was touched when test was run and test is not completed. Code 538 could also be output if Continuous Memory Code 214 (CID) is present. If Continuous Memory Code 214 is present, see appropriate chart under «DIAGNOSTIC TROUBLE CODE REFERENCE CHARTS»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) for instruction. For Code 136, 172 or 176, go to step 13). For Code 137, 173 or 177, go to step 24). For all other codes, go to step 14). CYLINDER BALANCE TEST SERVICE CODES Service Code Application 90 Pass 10 Cylinder No. 1 20 Cylinder No. 2 30 Cylinder No. 3 40 Cylinder No. 4 50 Cylinder No. 5 60 Cylinder No. 6 70 Cylinder No. 7 80 Cylinder No. 8 538 Retest NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 6) to step 8). No test procedures have been omitted.
6. 8) Check Injector & Harness Resistance (SFI) Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure and record resistance between suspected injector circuit test pin and test pin No. 37 at breakout box. For no-start, measure and record resistance between any injector circuit test pin and test pin No. 37 at breakout box. If resistance is 11-18 ohms, go to step 12). If resistance is not 11-18 ohms, repair open VPWR circuit for no-start or go to next step for all other conditions.
7. 9) Check Continuity Of Fuel Injector Harness Turn ignition off. Disconnect injector wiring harness connector at suspect injector. Set DVOM to 200-ohm scale. Measure resistance between test pins No. 37 and 57 at breakout box and VPWR terminal at suspect injector wiring harness connector. Also, measure resistance between injector test pin(s) at breakout box and same injector circuit terminal at each injector wiring harness connector. If each reading is less than 5 ohms, go to next step. If any reading is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components and drive vehicle for 5 miles at 55 MPH. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
8. 10) Check Injector Harness Circuit For Short To Power Or Ground Turn ignition off. With breakout box installed and PCM disconnected, disconnect suspect fuel injector wiring harness connector. Measure resistance between injector test pin(s) and test pins No. 37, 40, 46, 57 and 60. Also, measure resistance between injector test pin(s) at breakout box and chassis ground. If each resistance is 10,000 ohms or more, replace injector per cylinder balance test service code and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If each resistance is less than 10,000 ohms, repair short. Remove breakout box, reconnect all components and drive vehicle for 5 miles at 55 MPH. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 10) to step 13). No test procedures have been omitted.
9. 13) Check Thermactor Operation If vehicle is equipped with pulse-air or does not have secondary air injection system, go to next step. A HO2S which is always lean could be caused by thermactor air being diverted upstream from HO2S. With dual HO2S, Code 172 applies to right or rear HO2S and Code 136 or 176 applies to left or front HO2S. Turn ignition off. Disconnect secondary air hose(s) from pump and vent to atmosphere. Perform «KOER SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If Code 172, 136 or 176 is present, reconnect air hose(s) and go next step. If Continuous Memory Code 139, 144, 171, 176 or 177 is present, go to step 90). If Code 311, 312 or 313 is present, go to CIRCUIT TEST KC. If code(s) is not present, repair air injection system as necessary.
10. 14) Check HO2S Integrity A HO2S which is always lean, slow to switch or does not switch could be caused by: Moisture inside HO2S or connector causing a short to ground. HO2S coated with contaminants. HO2S circuit open. HO2S circuit shorted to ground. Turn ignition off. Inspect HO2S wiring harness for damage. Inspect HO2S and connector for signs of fluid entry. Repair or replace as necessary. Start engine, and run it at 2000 RPM for 2 minutes. Turn ignition off. Run «KOER SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If fault codes are present, go to step 16). If no codes are present, go to step 21). NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 14) to step 16). No test procedures have been omitted.
11. 16) Check HO2S (Engines With MAF Sensor) Purpose of this test is to verify HO2S can generate a voltage signal of greater than 0.5 volt during KOER SELF-TEST. Vacuum or air leaks in non-EEC-IV areas could cause Code 136, 172 or 176. Check following possibilities before continuing: Leaking vacuum actuated motor. Leaking intake gasket. EGR system. PCV system. Unmetered air between MAF sensor and throttle body. Lead-contaminated HO2S. Turn ignition off. Disconnect appropriate HO2S from harness. Connect DVOM between HO2S signal circuit terminal and HO2S GND circuit terminal at HO2S wiring harness connector. Run engine at 2000 RPM for 2 minutes. Repeat «KOER SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) and monitor HO2S voltage. If voltage is 0.5 volt or more at end of self-test, go to next step. If voltage is less than 0.5 volt, replace HO2S and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
12. 17) Check Continuity Of HO2S Ground Circuits Turn ignition off. Install breakout box, leaving PCM disconnected. Disconnect suspect HO2S wiring harness connector. Inspect connector for damage, moisture and corrosion. Repair as necessary. Measure resistance between test pin No. 46 at breakout box and HO2S GND circuit terminal at HO2S wiring harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, and reconnect all components. Drive vehicle for 5 minutes at 55 MPH. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
13. 18) Check HO2S Circuit For Short To Ground Turn ignition off. Leave breakout box installed and PCM disconnected. Disconnect HO2S. Measure resistance between HO2S circuit test pin and test pins No. 40, 46 or 49 at breakout box. If any reading is less than 10,000 ohms, repair short to ground. Drive vehicle at 55 MPH for 5 minutes and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If reading is 10,000 ohms or more, go to next step.
14. 19) Check HO2S For Short To Ground Ensure ignition is off and PCM is disconnected. With HO2S disconnected, measure resistance between PWR GND and HO2S circuit terminal at HO2S connector. Also, measure resistance between HO2S circuit terminal and HO2S GND terminal at HO2S wiring harness connector. If resistance is less than 10,000 ohms, replace HO2S. Drive vehicle for 5 miles at 55 MPH and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If resistance is 10,000 ohms or more, go to next step.
15. 20) Check Resistance Of HO2S Heating Element Turn ignition off. Disconnect suspect HO2S. Inspect both ends of connector for damage, moisture and corrosion. Repair as necessary. Measure resistance between IGNITION RUN circuit terminal or VPWR circuit terminal and PWR GND circuit at HO2S connector. Hot to warm engine resistance should be 5-30 ohms. Cold engine temperature resistance is 2-5 ohms. If resistance is within specification, go to next step. If resistance is not as specified, replace HO2S and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
16. 21) Check For Power At HO2S Harness Connector Disconnect HO2S. Turn ignition on. Measure voltage between negative battery terminal and IGNITION RUN circuit terminal at HO2S wiring harness connector. If voltage more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, repair open in IGNITION RUN circuit. Reconnect HO2S and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
17. 22) Check Continuity Of Power Ground Circuit Turn ignition off. Measure resistance between PWR GND circuit at HO2S wiring harness connector and negative battery terminal. If resistance is less than 5 ohms, repair open in IGNITION RUN circuit and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If resistance is 5 ohms or more, repair open in PWR GND circuit and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 22) to step 24). No test procedures have been omitted.
18. 24) Diagnostic Test Code 137, 173 Or 177: Check HO2S SIGNAL For Short To Power On dual HO2S systems, Code 173 applies to right or rear sensor. Codes 137 and 177 applies to left or front sensor. HO2S continuously rich could be caused by: Moisture inside wiring harness causing short to power. HO2S shorted to power. Turn ignition off. Disconnect suspect HO2S. Inspect connector for damage and repair as necessary. Turn ignition on. Measure voltage between HO2S and PWR GND terminals at HO2S wiring harness connector. If voltage is less than 0.5 volt, go to step 26). If voltage is 0.5 volt or more, go to next step.
19. 25) Check For Short To Power Turn ignition off. Disconnect suspect HO2S. Inspect wiring harness for damage and repair as necessary. Disconnect PCM 60-pin connector. Install Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between VPWR test pin No. 37/57 and HO2S test pin at breakout box. If resistance is 10,000 ohms or more, replace PCM. Remove breakout box, and reconnect all components. Drive vehicle 5 miles at 55 MPH. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If resistance is less than 10,000 ohms, repair short circuit. Remove breakout box, and reconnect all components. Drive vehicle 5 miles at 55 MPH. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
20. 26) Check HO2S For Short To IGNITION RUN Circuit Turn ignition off. Disconnect HO2S. Measure resistance between IGNITION RUN terminal and HO2S terminal at HO2S connector. If resistance is 10,000 ohms or more, go to next step for Codes 137, 173 and 177 or step 30) for all others. If resistance is less than 10,000 ohms, replace HO2S. Drive vehicle for 5 miles at 55 MPH, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
21. 27) Attempt To Generate Code 136, 172 Or 176 Turn ignition off. Disconnect appropriate HO2S. Connect a jumper wire between negative battery terminal and HO2S terminal at HO2S wiring harness connector. Repeat «KOER SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If Code 136, 172 or 176 is present, remove jumper wire and go to step 30). If Codes 136, 172 or 176 is not present, remove jumper wire. Disconnect PCM connector, and inspect it for damage. If connector is okay, replace PCM. Drive vehicle for 5 miles at 55 MPH. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 27) to step 30). No test procedures have been omitted.
22. 30) HO2S Check Turn ignition off. Disconnect HO2S. Connect DVOM to HO2S terminal and HO2S GND or SIG RTN terminal at HO2S connector. Create a vacuum leak to force HO2S to go lean (disconnect any vacuum hose). Start engine. Raise engine speed to about 2000 RPM. DVOM should indicate less than 0.4 volt within 30 seconds. If voltage is not as specified, replace HO2S. Reconnect vacuum hoses, and drive vehicle for 5 miles at 55 MPH. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If voltage is as specified, go to step 90). NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 30) to step 40). No test procedures have been omitted.
23. 40) Code 593: Check HO2S Heater Relay Operation Code 593 indicates that a primary HO2S heater failure has been detected. Possible causes for this fault are: Damaged HO2S heater relay. Open VPWR circuit. Open in relay control signal circuit. Short to power or ground in relay control signal circuit. Faulty Powertrain Control Module (PCM). Turn ignition off. Disconnect both HO2S connectors. Inspect HO2S wiring harness connectors for damage and repair as necessary. Connect DVOM positive lead to VPWR circuit terminal at HO2S wiring harness connector. Connect DVOM negative lead to PWR GND circuit terminal at HO2S wiring harness connector. Enter output state Diagnostic Test Mode (DTM). See «OUTPUT STATE DIAGNOSTIC TEST MODE (DTM)»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__output-state-diagnostic-test-mode-dtm) under ADDITIONAL SYSTEM FUNCTIONS. Once output state DTM has been entered, observe DVOM and depress and release throttle several times to cycle outputs. Voltage should cycle between 10.5 volts to less than 0.5 volt. Repeat voltage check on other HO2S connector. If voltage is as specified, fault is intermittent. Reconnect all components and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If voltage is not as specified, go to next step (if Code 593 is present) or go to step 46) (all others).
24. 41) Check VPWR Circuit Voltage Turn ignition off. Disconnect HO2S heater relay. Measure voltage between negative battery terminal and VPWR circuit terminal at HO2S wiring harness connector. If voltage is 10.5 volts or less, repair open circuit. Remove breakout box, reconnect all components and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If voltage is more than 10.5 volts, go to next step (if Code 593 is present) or step 46) (all others).
25. 42) Check HO2S Heater Relay Continuity Turn ignition off. Disconnect HO2S heater relay. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pin No. 14 at breakout box and HO2S signal circuit terminal at HO2S wiring harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
26. 43) Check For Short To Power Measure resistance between test pin No. 14 and test pins No. 37 and 57. If resistance is more than 10,000 ohms, go to next step. If resistance is 10,000 ohms or less, repair short to power. Remove breakout box, reconnect all components and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
27. 44) Check For Short To Ground Measure resistance between test pin No. 14 and test pins No. 40, 46 and 60. If resistance is more than 10,000 ohms, go to next step. If resistance is 10,000 ohms or less, repair short to ground. Remove breakout box, reconnect all components and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
28. 45) Check HO2S Heater Relay Coil Resistance Measure resistance between terminals No. 2 and 3 at HO2S heater relay. (Scheme 52) If resistance is 90-110 ohms, replace PCM. Remove breakout box, reconnect all components and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If resistance is not 90-110 ohms, replace relay. Remove breakout box, reconnect all components and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). (Scheme 52): Identifying HO2S Heater Relay Terminals
29. 46) Check For Closed HO2S Heater Relay Contact Turn ignition off. Disconnect HO2S heater relay connector. Measure resistance between terminal No. 2 (VPWR circuit) and terminal No. 3 (HO2S HTR circuit) at HO2S relay. (Scheme 52) If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, replace relay.
30. 47) Check VPWR Circuit Continuity Measure resistance between test pin No. 14 at breakout box and VPWR circuit terminal at HO2S relay wiring harness connector (check at both HO2S connectors). If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open circuit.
31. 48) Check Power Ground Continuity Check resistance between negative battery terminal and PWR GND circuit terminals at both HO2S wiring harness connectors. If resistance is 5 ohms or more, repair open in PWR GND circuit. If resistance is less than 5 ohms, replace HO2S heater relay. NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 48) to step 90). No test procedures have been omitted.
32. 90) Check Continuous Monitor Mode Start engine, and warm it to normal operating temperature. Raise engine speed to 2000 RPM for 2 minutes and then return to idle. Enter KOER wiggle test. See «CONTINUOUS MONITOR MODE (WIGGLE TEST)»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__continuous-monitor-mode-wiggle-test) under QUICK TEST. While observing DVOM or scan tester, shake or bend small sections of wiring harness from HO2S to PCM. Wiggle, shake or bend small sections of wiring harness from HO2S GND to PCM. If no fault is indicated, remain in CONTINUOUS MONITOR MODE and go to next step. If fault is indicated, isolate and repair fault as necessary. Clear codes. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
33. 91) Continuous Monitor Test Drive Check While still in KOER wiggle test, test drive vehicle for 5 miles at 55 MPH over smooth roads. Drive an additional 5 miles at 55 MPH over rough roads. If possible, drive vehicle through a pool of water to wet HO2S and connector. If fault is indicated, isolate fault and repair as necessary. Clear codes, and remove breakout box. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If no codes are indicated, exit KOER wiggle test and go to next step.
34. 92) Check HO2S Switching Turn ignition off. Inspect wiring harness for proper routing and insulation. Check for burnt, chaffed or open wires. Repair as necessary. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install breakout box. Connect PCM to breakout box. Connect analog voltmeter to suspect HO2S test pin and HO2S GND at breakout box. Test drive vehicle for 5 miles at 55 MPH while observing voltmeter. HO2S should switch from.3 volt to.9 volt within 3 seconds. If HO2S does not switch as described, replace HO2S. Connect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If HO2S switches as described, fault cannot be identified or duplicated at this time. See INTERMITTENTS in the «TESTS W/O CODES»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wo-codes) article.

Perform this test when directed by QUICK TEST or if directed by other test procedures. PCM uses adaptive fuel logic to compensate for normal variances in fuel system components. If fuel system appears to be too rich or too lean, adaptive fuel will make appropriate shift in fuel delivery calculations to compensate.

If possible, measure several known good MAP/BARO sensors. Average voltage reading will be typical for location and day of testing.

MAP SENSOR VOLTAGE OUTPUT

TEST PIN NO. 37/57 (VPWR) WIRE COLOR IDENTIFICATION

1. 1) Continuous Memory Codes 181, 183, 189 & 192 These codes identify a lean fuel condition resulting in adaptive fuel strategy enriching fuel system to compensate. Code 181 Indicates single right or rear HO2S detected a problem and adaptive fuel rich limit has been reached. Code 183 Indicates single right or rear HO2S detected a problem and adaptive fuel rich limit has been reached at idle. Code 189 Indicates left or front HO2S detected a problem and adaptive fuel rich limit has been reached. Code 192 Indicates left or front HO2S detected a problem and adaptive fuel rich limit has been reached at idle.
2. 1a) Continuous Memory Codes 179, 182, 188 & 191 These codes identify a rich fuel condition resulting in adaptive fuel strategy leaning fuel system to compensate. Code 179 Indicates right or rear HO2S detected a problem and adaptive fuel lean limit has been reached at idle. Code 182 Indicates right or rear HO2S detected a problem and adaptive fuel lean limit has been reached at idle. Code 188 Indicates left or front HO2S detected a problem and adaptive fuel lean limit has been reached. Code 191 Indicates left or front HO2S detected a problem and adaptive fuel lean limit has been reached. Possible causes for these codes are: Incorrect fuel pressure. Faulty fuel injector or circuit. Leaking or restricted air intake. Restricted air or fuel filter. If other codes are present, repair as necessary. If no other codes are present, go to next step.
3. 2) Check Fuel Pressure Release fuel system pressure. With ignition off, install fuel pressure gauge. Ensure manifold vacuum is connected to fuel pressure regulator. Start engine and allow to idle. For fuel pressure specifications, see «FUEL PRESSURE SPECIFICATIONS»(/lincoln/mark-viii/i-1992-1998/remont/specifications/#fuel-pressure-specifications) article. If fuel system pressure is not within specification, repair as necessary. See FUEL SYSTEM in the «SYSTEM/COMPONENT TESTS»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-46l) article. If fuel system pressure is within specification, go to next step. NOTE: For fuel pressure specifications, see «FUEL PRESSURE SPECIFICATIONS»(/lincoln/mark-viii/i-1992-1998/remont/specifications/#fuel-pressure-specifications) article.
4. 3) Check System Ability To Hold Fuel Pressure With fuel pressure gauge installed, cycle ignition from OFF to ON position 3-4 times to pressurize fuel system ( DO NOT start engine). If fuel pressure remains at specification for 60 seconds, go to next step (MAP/BARO equipped vehicles) or step 6) (all other vehicles). If fuel pressure does not remain at specification for 60 seconds, repair fuel system as necessary. See FUEL SYSTEM in the «SYSTEM/COMPONENT TESTS»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-46l) article.
5. 4) Check MAP/BARO Frequency Turn ignition off. Connect MAP/BARO tester to MAP/BARO sensor. (Scheme 38)in CIRCUIT TEST DF. Turn ignition on. If MAP/BARO voltage is within specification, go to step 6). See «MAP SENSOR VOLTAGE OUTPUT»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) table. If voltage is not within specification, check wiring to MAP/BARO sensor for corrosion and other damage. Repair as necessary. Clear Keep-Alive Memory (KAM), and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If wiring is okay, replace MAP/BARO sensor. Clear KAM, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 4) to step 6). No test procedures have been omitted.
6. 6) Cylinder Balance Test (SFI) Perform «KOER SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). After last code is displayed, wait 5-10 seconds. Enter CYLINDER BALANCE TEST by lightly goosing throttle (not WOT). Test time is about 2-3 minutes. To interpret codes retrieved from test, refer to CYLINDER BALANCE TEST SERVICE CODES table. If Code 90 is present, original fault is in ignition system. If Code 90 is not present, go to step 8). CYLINDER BALANCE TEST SERVICE CODES Service Code Application 90 Pass 10 Cylinder No. 1 20 Cylinder No. 2 30 Cylinder No. 3 40 Cylinder No. 4 50 Cylinder No. 5 60 Cylinder No. 6 70 Cylinder No. 7 80 Cylinder No. 8 538 Retest NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 6) to step 8). No test procedures have been omitted.
7. 8) Check Injector & Circuit Resistance (SFI) Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure and record resistance between suspected injector circuit test pin and test pin No. 37. See «FUEL INJECTOR TEST PIN NO. IDENTIFICATION»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) table in CIRCUIT TEST H. If each resistance is 11-18 ohms, go to step 12). If any resistance is not 11-18 ohms, go to next step.
8. 9) Check Continuity Of Fuel Injector Circuit Turn ignition off. Disconnect suspect injector wiring harness connector at injector. Measure resistance between test pins No. 37 and 57 at breakout box and each injector VPWR terminal at wiring harness connector. Measure resistance between injector test pin(s) at breakout box and same injector circuit terminal at each injector wiring harness connector. If each resistance is less than 5 ohms, go to next step. If any resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components and drive vehicle for 5 miles at 55 MPH. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
9. 10) Check Injector Circuit For Short To Power Or Ground Turn ignition off. With breakout box installed and PCM disconnected, disconnect suspect fuel injector wiring harness connector. Measure resistance between injector test pin(s) and test pins No. 37, 40, 46, 57 and 60. Also, measure resistance between injector test pin(s) at breakout box and chassis ground. If each resistance is 10,000 ohms or more, replace injector per cylinder balance test service code and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If each resistance is less than 10,000 ohms, repair short. Remove breakout box, reconnect all components and drive vehicle for 5 miles at 55 MPH. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 10) to step 12). No test procedures have been omitted.
10. 12) Check Injector Drive Signal With ignition off, connect PCM to breakout box. Connect a non-powered 12-volt test light between test pin No. 37 and suspect injector test pin at breakout box. Crank or start engine. If test light glows dimly, system is operating correctly. Clean injectors, and drive vehicle for 5 miles at 55 MPH. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) and CYLINDER BALANCE TEST. If test light does not glow dimly (no light/bright light), replace PCM. Reconnect all components, and drive vehicle for 5 miles at 55 MPH. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).

Perform this test when instructed by QUICK TEST or if directed by other test procedures. This test is only intended to diagnose

Scheme 53

1. CANP solenoid.
2. Harness circuits (CANP and VPWR).
3. Powertrain Control Module (PCM). (Scheme 53): Identifying Canister Purge (CANP) Circuit TEST PIN WIRE COLOR IDENTIFICATION Application Test Pin No. Wire Color CANP (1) Gray/Yellow VPWR 37 & 57 Red (1) (Scheme 53)

1. Check CANP Solenoid Operation Enter output state Diagnostic Test Mode (DTM). See «OUTPUT STATE DIAGNOSTIC TEST MODE (DTM)»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__output-state-diagnostic-test-mode-dtm) under ADDITIONAL SYSTEM FUNCTIONS. Once output state DTM has been entered, disconnect CANP solenoid. Connect DVOM positive test lead to VPWR terminal and negative test lead to CANP terminal at solenoid wiring harness connector. While observing DVOM, depress and release throttle several times to cycle output voltage on and off. If CANP circuit voltage does not cycle 0.2 volt or more, remove jumper wire and go to step 6). If CANP circuit voltage cycles, remain in output state DTM and go to next step.
2. Check CANP Resistance Turn ignition off. Measure resistance between CANP solenoid terminals. If resistance is 30-90 ohms, remain in output state DTM and go to next step. If resistance is not 30-90 ohms, replace CANP solenoid and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
3. Check Solenoid For Vacuum Leaks Turn ignition on. Leave CANP solenoid disconnected. Disconnect vacuum hose at CANP solenoid from manifold vacuum side of solenoid. Apply 16 in. Hg vacuum to manifold vacuum side of CANP solenoid. If CANP solenoid does not hold vacuum for 20 seconds, replace solenoid and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If fault is still present, service fuel evaporation canister or hoses. If CANP holds vacuum for 20 seconds, remain in output state DTM, leave vacuum pump attached and go to next step.
4. Check Solenoid Mechanical Operation Connect CANP solenoid connector. Apply 16 in. Hg vacuum to manifold vacuum side of CANP solenoid. Depress and release throttle. If vacuum is released, check hose from CANP solenoid to canister for leaks and cracks. If hose is okay, remove jumper wire from STI to SIG RTN and go to next step. If vacuum is not released, check hose from CANP solenoid to canister for blockage or kinks. If hose is okay, replace CANP solenoid and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
5. Check Vacuum Supply To CANP Solenoid Disconnect vacuum hose from CANP solenoid on manifold vacuum side. Start engine. If vacuum is present at vacuum hose, engine control system is okay. Check evaporative canister. If vacuum is not present at hose, check vacuum hose for improper routing, kinks and blockage. If hose is okay, check engine for mechanical cause of low vacuum.
6. Code 565 Or 569: Check VPWR To CANP Solenoid Code 565 or 569 indicates fault in CANP solenoid circuit. Possible causes for this fault are: Faulty CANP solenoid. Open or short circuit in wiring harness circuit. Faulty PCM. Turn ignition off. Disconnect CANP solenoid connector. Measure voltage between negative battery terminal and VPWR circuit terminal at CANP solenoid vehicle wiring harness connector. If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, repair open VPWR circuit. Reconnect components and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
7. Check CANP Resistance Turn ignition off. Measure resistance between CANP solenoid terminals. If resistance is 30-90 ohms, go to next step. If resistance is not 30-90 ohms, replace CANP solenoid and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
8. Check Continuity Of CANP Circuit Turn ignition off. Disconnect CANP solenoid. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between CANP circuit breakout box test pin (No. 11, 15 or 31) and CANP circuit terminal at CANP vehicle wiring harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
9. Check CANP Circuit For Short To Ground Turn ignition off. Disconnect scan tester from DLC, if applicable. With CANP solenoid disconnected, measure resistance between CANP circuit breakout box test pin (No. 11, 15 or 31) and pins No. 40, 46 and 60. If all readings are more than 10,000 ohms, go to next step. If any reading is 10,000 ohms or less, repair short to ground. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
10. Check CANP Circuit For Short To Power Turn ignition off. With CANP solenoid and PCM disconnected, measure resistance between CANP circuit breakout box test pin (No. 11, 15 or 31) and test pins No. 37 and 57. If all readings are more than 10,000 ohms, replace PCM. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If any reading is 10,000 ohms or less, repair short to power. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .

The IAC solenoid controls engine idle speed and dashpot functions by regulating the volume of air by-passing the throttle plate. IAC solenoid positioning is determined by signals sent from the PCM. Perform this test when instructed by QUICK TEST or if directed by other test procedures. This test is intended to diagnose

1. RPM during SELF-TEST mode.
2. IAC solenoid.
3. Wiring harness circuits (IAC and VPWR).
4. Powertrain Control Module (PCM).

To prevent replacement of good components, be aware the following non-EEC related areas may be at fault

Scheme 54

1. Engine temperature outside correct operating range.
2. A/C input (electrical problem).
3. Incorrect throttle stop adjustment.
4. Faulty throttle or cruise control linkage. (Scheme 54): Identifying Idle Air Control Circuit TEST PIN WIRE COLOR IDENTIFICATION Application Wire Color TEST PIN NO. 21 (IAC) White/Light Blue TEST PINS NO. 37 & 57 (VPWR) Red

Scheme 55

1. 1) Code 412: Check For RPM Drop Code 412 indicates engine RPM could not be controlled within upper RPM limit during KOER SELF-TEST. Possible causes for this fault are: Open or shorted circuit. Sticking or binding throttle linkage. Incorrect idle airflow setting. Throttle body or IAC solenoid contaminated. Faulty IAC solenoid. Faulty PCM. Mechanical faults unrelated to EEC-IV which could affect RPM. Turn ignition off. Connect tachometer to engine. Start engine. Disconnect Idle Air Control (IAC) harness. If RPM drops or engine stalls, go to next step. If RPM does not drop or engine does not stall, go to step 3).
2. 2) Check For EGR Codes If EGR service Code 213, 232, 326, 327, 328, 332, 334 or 336 is displayed, reconnect IAC solenoid. Go to appropriate KOER circuit test. See «DIAGNOSTIC TROUBLE CODE REFERENCE CHARTS»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If these codes are not displayed, go to next step.
3. 3) Check For Other Diagnostic Test Codes If Code 126, 136, 137, 172 or 173 is displayed, reconnect IAC solenoid. Go to appropriate KOER circuit test. See «DIAGNOSTIC TROUBLE CODE REFERENCE CHARTS»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If these codes are not displayed, go to next step.
4. 4) Measure IAC Solenoid Resistance Turn ignition off. Disconnect IAC solenoid. Connect DVOM positive lead to VPWR terminal and negative lead to IAC terminal. (Scheme 55) Measure resistance of IAC solenoid. If resistance is not 6-13 ohms, replace IAC solenoid and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If resistance is 6-13 ohms, go to next step. (Scheme 55): IAC Solenoid Connector
5. 5) Check For Internal Short To IAC Solenoid Case Turn ignition off. With IAC solenoid disconnected, measure resistance from either IAC terminal pin to IAC solenoid housing. If resistance is more than 10,000 ohms, go to next step. If resistance is 10,000 ohms or less, replace IAC solenoid. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
6. 6) Check VPWR Circuit Voltage Leave IAC harness disconnected. Turn ignition on. Measure voltage between VPWR terminal at IAC vehicle harness connector and negative battery terminal. If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, repair open circuit and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
7. 7) Check IAC Circuit Continuity Turn ignition off. Leave IAC solenoid disconnected. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pin No. 21 at breakout box and IAC terminal at IAC vehicle wiring harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open circuit and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
8. 8) Check IAC Circuit For Short To Ground Turn ignition off. Leave IAC solenoid and PCM disconnected. Measure resistance between test pin No. 21 and test pins No. 40, 46 and 60 at breakout box. If any reading is 10,000 ohms or less, repair short to ground. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If all readings are more than 10,000 ohms, go to next step.
9. 9) Check IAC Circuit For Short To Power Leave IAC solenoid and PCM disconnected. Turn ignition on. Measure voltage between breakout box test pin No. 21 and chassis ground. If voltage is less than 1.0 volt, go to next step. If voltage is 1.0 volt or more, repair short circuit and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). After repair is complete, if code or symptom is still present, replace PCM.
10. 10) Check IAC Signal From PCM Turn ignition off. Reconnect IAC solenoid. Connect PCM to breakout box. Connect DVOM between test pins No. 21 and 40 at breakout box. Start engine. Observe DVOM while slowly increasing engine speed to 3000 RPM. If voltage is 3.0-11.5 volts, go to next step. If voltage is not 3.0-11.5 volts, remove IAC solenoid to confirm that it is not stuck open. If IAC is okay, replace PCM and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
11. 11) Check Base Idle Verify base idle speed correct. See «ADJUSTMENTS»(ref-23158) article. If base idle speed is within specification, remove IAC solenoid and inspect for contamination. Clean or replace solenoid as necessary. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If code or symptom is still present, replace IAC solenoid. If base idle speed is not correct, reset idle speed to specification. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If unable to set idle to specification, go to next step. CAUTION: One of 3 IAC solenoid valves may be used. Two are Hitachi solenoids and one is a Nippondenso solenoid. The only IAC solenoid valve that can be cleaned is the Hitachi solenoid that has a Silver metal housing. The Nippondenso solenoid or the Hitachi solenoid without the Silver metal housing must be replaced if contaminated.
12. 12) Check For Faults Affecting Idle Speed Check following mechanical items for faults: Throttle linkage and/or cruise control linkage (sticking or binding). Throttle body (contamination). Vacuum hoses. Check Vehicle Emission Control Information (VECI) label. Check for leaks around IAC solenoid (gaskets, etc.). If any of these items are faulty, service as necessary, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If all of these items are okay, remove IAC solenoid and inspect for contamination. Clean or replace solenoid as necessary. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If code or symptom is still present, replace IAC solenoid. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 12) to step 15). No test procedures have been omitted.
13. 15) Code 411 Code 411 indicates engine RPM could not be controlled within lower RPM limit during KOER SELF-TEST. Possible causes for this fault are: Incorrect idle airflow setting. Vacuum leaks. Sticking or binding throttle linkage. Throttle plates open. Incorrect ignition timing (distributor ignition only). Throttle body or IAC solenoid contamination. IAC circuit shorted to ground. Faulty IAC solenoid. If above items are okay and idle is set to specification, remove IAC solenoid and inspect for contamination. Repair or replace as necessary. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If code or symptom is still present, replace IAC solenoid. If idle speed is not within specification, adjust as necessary and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If idle speed cannot be set to specification, go to next step.
14. 16) Check For Conditions Affecting Idle Speed Check the following mechanical components: Vacuum hoses. Check Vehicle Emission Control Information (VECI). Throttle linkage and/or cruise control linkage (sticking or binding). Ensure throttle plates are fully closed. Induction system (vacuum leaks). Throttle body (contamination). Ensure CANP solenoid is not stuck open. Ensure base ignition timing is to specification on emission decal (distributor ignition only. If everything checks okay, go to next step. If fault is found, service as necessary and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
15. 17) Check For Internal Short To IAC Solenoid Case Turn ignition off. Disconnect IAC solenoid wiring harness connector. Measure resistance from either IAC terminal pin to IAC solenoid housing. If resistance is more than 10,000 ohms, go to next step. If resistance is 10,000 ohms or less, replace IAC solenoid. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
16. 18) Check IAC Circuit For Short To Ground Turn ignition off. Leave IAC solenoid disconnected. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pin No. 21 and test pins No. 40, 46 and 60. If any reading is 10,000 ohms or less, repair short to ground. Reconnect components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If all readings are more than 10,000 ohms, go to next step.
17. 19) Check IAC Signal From PCM Turn ignition off. Connect PCM to breakout box. Reconnect IAC solenoid. Set DVOM on 20-volt scale. Connect DVOM between test pins No. 21 and 40 at breakout box. Start engine. Observe DVOM while slowly increasing engine speed to 3000 RPM. If voltage is not 3.0-11.5 volts, replace PCM and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If voltage is 3.0-11.5 volts, remove IAC solenoid and inspect for contamination. Clean or replace IAC solenoid as necessary, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If code or symptom is still present, replace IAC solenoid.

Perform this test when instructed during QUICK TEST. Use this test only to diagnose

1. FPRC solenoid.
2. Wiring harness circuits (FPRC and VPWR).
3. Faulty Powertrain Control Module (PCM).

To prevent replacement of good components, be aware the following non-EEC areas may be cause of driveability concerns

Scheme 56

1. Fuel pressure regulator.
2. Engine not obtaining correct operating temperature.
3. Vacuum hoses leaking or misrouted.
4. Excessive internal engine wear or damage. (Scheme 56): Fuel Pressure Regulator Control (FPRC) Solenoid Circuit

1. Code 554: Enter Output State Diagnostic Test Mode (DTM) Code 554 indicates fault in FPRC circuit. Possible causes are: Faulty FPRC solenoid. Vacuum hoses leaking or misrouted. Open or shorted circuit. Faulty PCM. Enter Output State Diagnostic Test Mode (DTM). See «OUTPUT STATE DIAGNOSTIC TEST MODE (DTM)»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__output-state-diagnostic-test-mode-dtm) under ADDITIONAL SYSTEM FUNCTIONS. Once output state DTM has been entered, disconnect FPRC solenoid connector. Connect DVOM positive lead to VPWR circuit terminal at FPRC solenoid wiring harness connector. Connect DVOM negative lead to FPRC circuit terminal at FPRC wiring harness connector. Set DVOM to 20 volt scale. Observe DVOM and depress and release throttle several times to cycle solenoid output. If FPRC solenoid voltage increases to more than 1.0 volt, reconnect FPRC solenoid, remove jumper wire and go to next step. If FPRC solenoid does not increase to more than 1.0 volt, remove jumper wire and go to step 6).
2. Check Vacuum Hose Turn ignition off. Disconnect vacuum hose between manifold vacuum source and FPRC solenoid input port. Inspect vacuum hose for kinks, blockage and cracks. Replace hose as necessary. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If hose is okay, go to next step.
3. Check FPRC Vacuum Signal Turn ignition off. Using a vacuum tee, connect vacuum gauge between manifold vacuum source and FPRC solenoid input port. Start engine and observe vacuum gauge. If vacuum is present, remove vacuum gauge and go to next step. If vacuum is not present, check engine mechanical condition (valves, vacuum leaks, timing, EGR valve, etc.).
4. Check Vacuum Hose Turn ignition off. Disconnect vacuum hose between FPRC solenoid output port and fuel pressure regulator. Inspect vacuum hose for kinks, cracks and blockage. Replace hose as necessary. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If hose is okay, reconnect hose and go to next step.
5. Check FPRC Solenoid Operation Turn ignition off. Install vacuum gauge between FPRC solenoid output port and fuel pressure regulator. Perform road test as follows: Warm engine to normal operating temperature. Observe vacuum gauge and accelerate heavily to 40 MPH. Observe vacuum gauge and decelerate to a steady cruise below 20 MPH. Vacuum gauge should indicate a low vacuum (FPRC solenoid closed) during heavy acceleration and a higher vacuum (FPRC solenoid open) during steady cruise if FPRC solenoid is functioning properly. Repeat test as necessary to confirm test results. If vacuum signal is as specified, remove vacuum gauge and check for fuel system malfunction. See FUEL SYSTEM in the «SYSTEM/COMPONENT TESTS»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-46l) article. If vacuum signal is not as specified, replace FPRC solenoid. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
6. Check FPRC Solenoid VPWR Turn ignition off. Disconnect FPRC solenoid connector. Turn ignition on. Measure voltage between VPWR terminal at FPRC wiring harness connector and negative battery terminal. If voltage is 10.5 volts or less, repair open circuit and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If voltage is more than 10.5 volts, go to next step.
7. Check FPRC Circuit Continuity Turn ignition off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Disconnect FPRC solenoid wiring harness connector. Measure resistance between test pin No. 32 and FPRC circuit terminal at FPRC solenoid wiring harness connector. If resistance is 5 ohms or more, repair open circuit. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If resistance is less than 5 ohms, go to next step.
8. Check FPRC Circuit For Short Leave ignition off and FPRC solenoid disconnected. Measure resistance between test pin No. 32 and test pins No. 37 and 57. Also, measure resistance between test pin No. 32 and test pins No. 40, 46 and 60. If any reading is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If each reading is more than 10,000 ohms, replace PCM. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .

Enter this test when directed by QUICK TEST. This test is only intended to diagnose

1. Harness circuits (SIG RTN and OCT ADJ).
2. Octane adjust shorting bar connector.

Purpose of Octane Adjust Shorting Bar is to provide optimum spark advance for fuel used. If engine detonates (spark knock), remove Octane Shorting Bar. This retards spark advance about 3-4 degrees. If engine continues to detonate, use fuel with a higher octane rating.

Octane Adjust Circuit. Scheme 57

TEST PIN WIRE COLOR ID

Octane Adjust (OCT ADJ) shorting bar is similar in shape to SPOUT in-line connector and on some models the Power Steering Pressure (PSP) circuit will also have a similar shorting bar connector. DO NOT remove OCT ADJ shorting bar unless instructed to do so.

1. Code 341 Code 431 indicates Octane Adjust (OCT ADJ) shorting bar is not in place or OCT ADJ circuit is open. Turn ignition off. Inspect Octane Adjust in-line connector. If shorting bar has been removed, go to next step. If shorting bar is in place, go to step 4).
2. Check For Modification Decal If vehicle has modification decal indicating OCT ADJ shorting bar was removed as a factory authorized procedure, testing is complete. If engine is detonating, go to the «TESTS W/O CODES»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wo-codes) article. If vehicle does not have modification decal, go to next step.
3. Check For Code 341 Replace OCT ADJ shorting bar. Perform «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) . If Code 341 is present, go to next step. If Code 341 is not present, testing is complete. If driveability faults are present, go to the appropriate «TESTS W/O CODES»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wo-codes) article.
4. Check Octane Adjust Circuit Continuity Continuity should exist from OCT ADJ circuit, through in-line connector and shorting bar, to SIG RTN circuit. Turn ignition off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pin No. 46 and OCT ADJ test pin at breakout box. If resistance is 5 ohms or more, repair open OCT ADJ circuit, shorting bar or SIG RTN circuit. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If resistance is less than 5 ohms, replace PCM and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
5. Check For Code 111 Start engine. Warm it to normal operating temperature. Turn ignition off. Perform «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) . If Code 111 is present, go to next step. If Code 341 is present, return to step 1). For all other codes, return to «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
6. Verify In-Line Shorting Bar Is Installed Turn ignition off. Inspect OCT ADJ in-line connector. If shorting bar is installed, go to step 8). If shorting bar is not installed, go to next step.
7. Check For Modification Decal If vehicle has modification decal indicating OCT ADJ shorting bar was removed as a factory authorized procedure, go to step 10. If vehicle does not have a modification decal, replace shorting bar. If engine is detonating, go to the «TESTS W/O CODES»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wo-codes) article.
8. Check For Technical Service Bulletin (TSB) If a TSB authorizing removal of OCT ADJ shorting bar exists, go to next step. If a TSB authorizing removal of OCT ADJ shorting bar does not exist, testing is complete. If engine is detonating, go to the «TESTS W/O CODES»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wo-codes) article.
9. Remove OCT ADJ Shorting Bar Turn ignition off. Remove OCT ADJ shorting bar. Test drive vehicle to verify complaint. If detonation is present, go to next step. If detonation is not present, EEC-IV is okay. Testing is complete.
10. Check Octane Adjust Circuit For Short To Ground Turn ignition off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between OCT ADJ terminal at in-line connector and test pins No. 40, 46 and 60 at breakout box. If resistance is 10,000 ohms or less, repair short circuit. If engine is detonating, go to the «TESTS W/O CODES»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wo-codes) article. If each resistance is more than 10,000 ohms, go to next step.
11. Check PCM Turn ignition off. Disconnect OCT ADJ shorting bar. Connect PCM to breakout box. Turn ignition on. Measure voltage between breakout box OCT ADJ test pin terminal and test pins No. 40 or 60. If voltage is 4 volts or less, replace PCM. If engine is detonating, go to the «TESTS W/O CODES»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wo-codes) article. If voltage is more than 4 volts, remove breakout box. If engine is detonating, go to the same article.

Perform this test only when instructed by QUICK TEST or directed here by a driveability symptom. This test is only intended to diagnose

1. Wiring harness circuits (VPWR and IMRC).
2. Intake Manifold Runner Control (IMRC) solenoid.
3. Faulty Powertrain Control Module (PCM).

To prevent replacing good components, check the following non-EEC areas for faults

Scheme 58

1. Vacuum tank leaks.
2. Vacuum hose leaks. (Scheme 58): IMRC Circuit TEST PIN NO. 32 OR 34 (IMRC) WIRE COLOR IDENTIFICATION Application Test Pin No. Wire Color Mark VIII 32 Light Green/Black

1. Code 551: Check IMRC Solenoid Resistance Code 551 indicates IMRC solenoid output voltage did not change when IMRC was activated during KOEO SELF-TEST. Possible causes for this fault are: IMRC circuit open or shorted. Faulty IMRC solenoid. PCM output driver open or grounded. Turn ignition off. Disconnect IMRC solenoid wiring harness connector. Measure resistance between IMRC solenoid terminals. If resistance is not 50-100 ohms, replace solenoid and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If resistance is 50-100 ohms, go to next step.
2. Check Voltage Of VPWR Circuit Turn ignition on. Measure voltage between VPWR terminal of IMRC solenoid wiring harness connector and negative battery terminal. If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, repair open circuit and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
3. Check Continuity Of IMRC Solenoid Circuit Turn ignition off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pin No. 32 at breakout box and IMRC circuit terminal at IMRC solenoid wiring harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
4. Check IMRC Circuit For Short To Ground Turn ignition off. Measure resistance between test pin No. 32 and test pins No. 40, 46 and 60. If all readings are more than 100,000 ohms, go to next step. If any reading is 100,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
5. Check IMRC Circuit For Short To Power Turn ignition off. Measure resistance between test pin No. 32 and test pins No. 37 and 57 at breakout box. If all readings are 100,000 ohms or more, replace PCM and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If any reading is less than 100,000 ohms, repair short circuit and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If fault is still present, replace PCM. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
6. Check IMRC Valves Turn ignition off. Disconnect vacuum lines from both IMRC valves. Use vacuum pump to apply 10 in. Hg vacuum to each IMRC valve. If both valves hold vacuum, go to next step. If valve(s) do not hold vacuum, replace valve as necessary and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
7. Check Operation Of IMRC Valves Apply 10 in. Hg to each air valve. If both valves and mechanical linkage move in response to applied vacuum, go to next step. If valves and/or linkage do not move, repair as necessary and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
8. Check Vacuum Hoses To IMRC Valves Check vacuum lines from IMRC valves to solenoids. Inspect vacuum lines for damage and blockage. If vacuum lines are damaged or blocked, repair as necessary. If vacuum lines are okay, go to next step.
9. Enter OUTPUT STATE CHECK Enter output state Diagnostic Test Mode (DTM). See «OUTPUT STATE DIAGNOSTIC TEST MODE (DTM)»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__output-state-diagnostic-test-mode-dtm) under ADDITIONAL SYSTEM FUNCTIONS. Once output state DTM has been entered, disconnect IMRC solenoid connector. Connect DVOM positive lead to VPWR circuit terminal at IMRC solenoid wiring harness connector. Connect DVOM negative lead to IMRC circuit terminal at IMRC solenoid wiring harness connector. Set DVOM to 20 volt scale. Observe DVOM and depress and release throttle several times. If IMRC voltage cycles to more than 0.5 volt, remain in output state DTM and go to next step. If IMRC voltage does not cycle to more than 0.5 volt, return to step 1).
10. Check IMRC Solenoid Vacuum Disconnect IMRC solenoid vacuum hose and wiring harness connector. Turn ignition on. Use vacuum pump to apply 16 in. Hg vacuum to each IMRC valve. If vacuum is not held for 20 seconds, replace solenoid and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If vacuum is held, go to next step.
11. Check IMRC Solenoid Mechanical Operation Remain in output state DTM. Using vacuum pump, apply 16 in. Hg vacuum to each IMRC valve. Depress and release throttle. If vacuum is not released, replace solenoid and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If vacuum is released, go to next step.
12. Disconnect IMRC solenoid vacuum hose. Start engine. Check vacuum at disconnected hose. If vacuum is present at hose, system is okay. If vacuum is not present, check supply hose to IMRC solenoid. Repair as necessary, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .

To prevent replacing good components, be aware the following non-EEC related areas may be cause of problem

1. Technician did not perform brief Wide Open Throttle (WOT) after Dynamic Response Code.
2. Engine did not go over 2000 RPM during WOT.

This test is only intended to diagnose

1. Throttle movement (minimum 3/4 throttle).
2. RPM increase is more than 2000 RPM.

If throttle is snapped open briefly, it may not pass WOT test. Ensure throttle is depressed fully to WOT and engine speed exceeds 2000 RPM.

Code 538 Displayed: System Failed To Recognize WOT Test

Repeat KOER SELF-TEST as follows

1. Activate SELF-TEST.
2. Start engine.
3. Observe ID Code start of test.
4. Observe Dynamic Response Code 1 (Code 0 with STAR tester).
5. Perform brief WOT.
6. Testing is complete; Diagnostic Test Code (DTC) output begins.

Ensure vehicle speed reached 2000 RPM during WOT. If engine speed did not reach 2000 RPM, check for binding throttle linkage. If Code 538 is present, replace PCM. Repeat QUICK TEST . If Code 538 is not present, vehicle has passed dynamic response test. Service other codes if necessary.

The MIL is turned on when PCM detects a fault in EEC circuit(s). The light will remain on as long as fault remains in system.

Perform this test only when instructed by QUICK TEST or if directed by CIRCUIT TEST QA . This test does not include procedure for models with electronic instrument panel. To prevent replacing good components, be aware that fuse, bulb or bulb socket may be cause of problem. This test is only intended to diagnose

Scheme 59

1. STO/MIL circuit.
2. Faulty PCM. (Scheme 59): Identifying Data Link Connector (DLC) Terminals TEST PIN WIRE COLOR IDENTIFICATION Application Test Pin No. Wire Color STO/MIL 17 Pink/Light Green DATA + 18 Tan/Orange DATA - 19 Pink/Light Blue

1. 1) Malfunction Indicator Light (MIL) Always On If vehicle will not start, go to appropriate circuit test: For Distributor Ignition (DI) systems, CIRCUIT TEST AA. For distributorless ignition systems (low data rate), CIRCUIT TEST AB. For distributorless ignition systems (high data rate), «CIRCUIT TEST AC»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__circuit-test-ac-no-start-ei) . If vehicle will start, service all KOEO and Continuous Memory Codes before proceeding with this test. Turn ignition off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pins No. 17 and 40 at breakout box. If resistance is 5 ohms or more, replace PCM and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If resistance is less than 5 ohms, repair short between test pin No. 17 and Data Link Connector (DLC) or MIL. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
2. 2) Malfunction Indicator Light (MIL) Does Not Light If vehicle will not start, go to step 1). Turn ignition on. Measure voltage between negative battery terminal and ground side of MIL fuse. If voltage is more than 10.5 volts, go to step 4). If voltage is 10.5 volts or less, go to next step.
3. 3) Check For Voltage At Fuse Turn ignition on. Measure voltage from negative battery terminal to power side of MIL fuse. If voltage is more than 10.5 volts, replace fuse. Verify repair by turning ignition on. If voltage is 10.5 volts or less, repair open MIL/B+ circuit. Verify repair by turning ignition on.
4. 4) Check Voltage At B+ Circuit Turn ignition on. Measure voltage between B+ side of MIL bulb socket and negative battery terminal. If voltage is 10.5 volts or less, repair open in MIL circuit between fuse and bulb. Verify repair by turning ignition on. If voltage is more than 10.5 volts, go to next step.
5. 5) Check MIL Bulb Response To Grounding Turn ignition off. Attach jumper wire between ground side of MIL bulb socket and chassis ground. Turn ignition on. If MIL light comes on, remove jumper wire, and go to next step. If MIL light does not come on, remove jumper wire. Replace MIL bulb socket. Turn ignition on to verify correct MIL operation.
6. 6) Check Continuity Of MIL Circuit Turn ignition off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pin No. 17 at breakout box and MIL wiring harness connector terminal. If resistance is less than 5 ohms, replace PCM. Turn ignition on to verify correct MIL operation. If resistance is 5 ohms or more, repair open in ground side of MIL circuit. Turn ignition on to verify correct MIL operation. NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 6) to step 10). No test procedures have been omitted.
7. 10) MIL On Intermittently, Check For Intermittent Short From STO To Ground If vehicle does not start, go to step 1). MIL comes on when a fault code is present. Service all fault codes before proceeding. If no codes are output, proceed with this test. Enter KOEO wiggle test. See «CONTINUOUS MONITOR MODE (WIGGLE TEST)»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__continuous-monitor-mode-wiggle-test) under QUICK TEST. Check DVOM for indication of fault while performing wiggle test on harness in the following areas: From Data Link Connector (DLC) to dash panel. Dash panel to PCM. Dash panel to Malfunction Indicator Light (MIL). If a fault is indicated, repair short to ground and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If a fault is not indicated, fault cannot be duplicated at this time. Testing is complete. NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 10) to step 15). No test procedures have been omitted.
8. 15) MIL Flashes With Erratic Idle Symptoms indicate STI is grounded and PCM is performing self-test without tester installed. Turn ignition off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between STI connector and engine ground. If resistance is less than 10,000 ohms, repair short circuit. Reconnect PCM, and turn ignition on to verify correct MIL operation. If resistance is 10,000 ohms or more, MIL circuit is okay. Verify symptom, and test for other rough idle symptoms. NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 15) to step 20). No test procedures have been omitted.
9. 20) CHECK ENGINE Message Displayed If vehicle will not start, go to step 1). Perform «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) . If result is Code 111-10-111 (pass code), fault is in instrument cluster. If pass code is not displayed, service codes as necessary. NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 20) to step 25). No test procedures have been omitted.
10. 25) Continuous Memory Code 529 Or 533: CHECK ENGINE Or CHECK DCL Message Displayed Codes 529 and 533 indicate circuit fault has occurred on Data Communications Link (DCL). These codes can occur alone or with another code. Fault will occur under following conditions: Code 529 indicates PCM or DCL circuit failure. Code 533 indicates DCL to electronic instrument cluster circuit failure. If vehicle does not start, go to step 1). If vehicle starts, clear continuous memory codes. Wait 5 minutes, and repeat «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) . If result is pass code (Code 111-10-111), fault is in instrument cluster. If pass code is not displayed, service codes as necessary.

The IDM is an input signal to the PCM that verifies spark plug fire based on ignition coil primary discharge. IDM signal consists of a single pulse for each engine RPM. No IDM pulse indicates secondary ignition misfire.

Perform this test when directed by QUICK TEST . This test is only intended to diagnose EEC-IV portion of ignition system. For additional information on ignition system and component testing, see the SYSTEM/COMPONENT TESTS article. To prevent replacing good components, be aware following non-EEC related areas may be at fault

1. Ignition Control Module (ICM).
2. Ignition coil packs.
3. Spark plugs and/or wires.
4. Crankshaft Position (CKP) sensor.
5. Secondary ignition short to ground.

This test is intended to diagnose

Scheme 60

1. Wiring harness circuits (IDM and SPOUT).
2. Powertrain Control Module (PCM). (Scheme 60): IDM Circuit Schematic

1. Continuous Memory Code 211: Erratic Ignition Code 211 indicates 2 successive erratic Profile Ignition Pick-Up (PIP) pulses occurred. Possible causes for this fault are: Loose wires or connectors. Secondary ignition short to ground. On-board transmitter equipment (2-way radio). If any of the above possible causes are found, repair as necessary. Clear code, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . Attempt to start vehicle. If vehicle does not start, go to «CIRCUIT TEST AC»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__circuit-test-ac-no-start-ei) . If vehicle starts, run engine for 5-10 minutes exercising throttle. Repeat KOEO portion of SELF-TEST and record any continuous memory codes. If Continuous Memory Code 211 is present, go to next step. If Continuous Memory Code 211 is not present, fault is intermittent. See INTERMITTENTS in the «TESTS W/O CODES»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wo-codes) article.
2. Code 226: IDM Circuit Failure Code 226 indicates PCM did not receive IDM signal from ICM in KOEO SELF-TEST. Possible causes for this problem are: Open or short in IDM or IGN GND circuit wiring harness. Faulty ICM. If engine does not start, go to IGNITION SYSTEMS in the «SYSTEM/COMPONENT TESTS»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-46l) article. If engine starts, go to step 4).
3. Continuous Memory Code 212: Check For Other Codes Code 212 indicates loss of IDM input signal to PCM. Possible causes for this fault are: Open or short circuit in wiring harness. Faulty ICM. Faulty PCM. Clear code, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . Attempt to start vehicle. If vehicle does not start, go to CIRCUIT TEST AC. If vehicle starts, run engine for 5-10 minutes exercising throttle. Repeat KOEO portion of SELF-TEST and record any continuous memory codes. If Continuous Memory Code 212 is present, go to next step. If Continuous Memory Code 215, 216 or 217 is present, go to IGNITION SYSTEMS in the «SYSTEM/COMPONENT TESTS»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-46l) article. If Continuous Memory Code 212, 215, 216 or 217 is not present, fault is intermittent. See INTERMITTENTS in the «TESTS W/O CODES»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wo-codes) article.
4. Code 212: Check IDM Circuit Continuity Turn ignition off. Disconnect ICM. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pin No. 4 at breakout box and pin No. 2 (IDM circuit) at ICM wiring harness connector. If resistance is 5 ohms or more, repair open circuit. Clear codes and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If resistance is less than 5 ohms, go to next step.
5. Check IDM Circuit For Short To Power (Except VREF) Leave PCM and ICM disconnected. Monitor circuit voltage by connecting DVOM between test pin No. 4 and test pins No. 40 or 60. To check VBAT circuit, turn ignition off. To check VPWR circuit, turn ignition on. If any reading is more than 10.5 volts, repair short to power. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If voltage is 10.5 volts or less, go to next step.
6. Check IDM Circuit For Short To VREF & PIP Turn ignition off. Ensure PCM and ICM are disconnected. Disconnect scan tool (if applicable). To check for shorts to VREF, use DVOM to measure resistance between test pins No. 4 and 26 at breakout box. To test for shorts to PIP, measure resistance between test pins No. 4 and 56 at breakout box. If resistance is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If resistance is more than 10,000 ohms, go to next step.
7. Check IDM Circuit For Short To Ground Leave PCM and ICM disconnected. Measure resistance between test pin No. 4 and test pins No. 40, 46 and 60 at breakout box. If any reading is 10,000 ohms or less, repair short to ground in IDM circuit. Clear codes and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If all resistances are more than 10,000 ohms, go to next step.
8. Check ICM Leave ignition off. Connect ICM to wiring harness connector. Connect PCM to breakout box. Start engine, and allow it to idle. Connect DVOM to test pin No. 4 and No. 16. Start engine. Observe DVOM for voltage surge (fault) while lightly tapping on ignition components to simulate road shock. Wiggle both ICM wiring harness connectors. If fault is indicated, disconnect and inspect ICM wiring harness connectors and terminals for damage. If connectors and terminals are okay, check ignition system. See the «SYSTEM/COMPONENT TESTS»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-46l) article. If fault is not indicated, leave DVOM connected to breakout box and go to next step.
9. Check EEC-IV Harness Ensure engine is idling at correct RPM. Wiggle, shake or bend small sections of harness, working from ICM connectors to firewall. Observe DVOM for indication of fault. Repeat process from firewall to PCM. If fault is indicated, isolate fault and repair wiring harness. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If no fault is indicated, go to next step.
10. Check PCM & Harness Connectors Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Clear codes, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If connector is okay, go to next step.
11. Check PCM For Short To Power Turn ignition off. Disconnect ICM connectors. Connect PCM to breakout box. Measure voltage between test pin No. 4 and chassis ground. Turn ignition on. Measure voltage between test pin No. 4 and pins No. 40 and 60. If any reading is more than 10.5 volts, replace PCM. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If each reading is 10.5 volts or less, go to next step.
12. Check PCM For Short To Ground Turn ignition off. Leave ICM connectors disconnected. Ensure PCM is connected to breakout box. Measure resistance between test pin No. 4 and pins No. 16, 20, 40, 46 and 60. If all readings are more than 10,000 ohms, EEC system is okay. Check ignition system. See the «SYSTEM/COMPONENT TESTS»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-46l) article. If any reading is 10,000 ohms or less, replace PCM. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .

During this test, a short to SIG RTN (pin No. 46) may be indicated along with an actual short to PWR GND when 4-wire HO2S is connected to vehicle wiring harness.

Perform this test when checking computed timing or if directed by QUICK TEST . This test is intended to diagnose

1. SPOUT wiring harness circuit.
2. Base timing.
3. Powertrain Control Module (PCM).

To prevent replacing good components, be aware the following non-EEC related areas may be at fault

Scheme 61

1. Basic engine condition (valves, vacuum leaks, valve timing, etc.).
2. ICM.
3. Crankshaft Position Sensor (CKP). (Scheme 61): Identifying ICM Connector Terminals

1. Check For Power To PCM Turn ignition off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Turn ignition on. Measure voltage between test pins No. 37 and 40 at breakout box. Also, measure voltage between test pins No. 57 and 60 at breakout box. If both readings are more than 10.5 volts, go to next step. If any reading is 10.5 volts or less, go to «CIRCUIT TEST XB»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
2. Check SPOUT Circuit For Continuity Turn ignition off. Disconnect ICM. Measure resistance between test pin No. 36 at breakout box and SPOUT terminal at ICM wiring harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open circuit and check ignition timing.
3. Check SPOUT Circuit For Shorts To Power (Except VREF) Turn ignition off. Leave PCM and ICM disconnected. Measure voltage between test pin No. 36 and test pin No. 40 or 60 at breakout box. Turn ignition off to check for short to VBAT or turn ignition on to check for short to VPWR. If any reading is more than 10.5 volts, repair short circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If voltage is 10.5 volts or less, go to next step. NOTE: When performing step 4), a short to SIG RTN (pin No. 46) may be indicated along with an actual short to PWR GND when 4-wire HO2S is connected to vehicle wiring harness.
4. Check SPOUT Circuit For Shorts To VREF, Ground & PIP Turn ignition off. Leave PCM and ICM disconnected. To check for shorts to ground, measure resistance between test pin No. 36 and test pins No. 16, 20, 40, 46 and 60. To check for shorts to VREF, measure resistance between test pins No. 26 and 36. To check for shorts to PIP circuit, measure resistance between test pins No. 36 and 56. If all readings are more than 10,000 ohms, check ignition system. See IGNITION SYSTEMS in the «SYSTEM/COMPONENT TESTS»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-46l) article. If any reading is 10,000 ohms or less, repair short circuit and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .

Aftermarket devices, such as alarm system, may cause SELF-TEST to abort if wiring is connected to certain EEC components. If a device is installed, disconnect it completely from EEC system. Before continuing with this circuit test, restore EEC circuits to original state and repeat QUICK TEST .

Perform this test when directed by QUICK TEST or other test procedures. This test is intended to diagnose

Scheme 62

1. Powertrain Control Module (PCM).
2. EEC power relay.
3. Constant Control Relay Module (CCRM).
4. Wiring harness circuits (HO2S, SIG RTN, STO, STI, VPWR and VREF). (Scheme 62): No Codes/Codes Not Listed Circuits TEST PIN WIRE COLOR IDENTIFICATION Application Wire Color TEST PIN NO. 17 (STO/MIL) Pink/Light Green TEST PINS NO. 37 & 57 (VPWR) Red TEST PIN NO. 46 (SIG RTN) Gray/Red TEST PIN NO. 48 (STI) White/Purple

1. Check VREF Voltage At Data Link Connector (DLC) Turn ignition off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect PCM to breakout box. Turn ignition on. Measure voltage between test pin No. 26 at breakout box and SIG RTN terminal at DLC. If reading is 4-6 volts, go to step 3). If reading is not 4-6 volts, go to next step.
2. Check SIG RTN Circuit Continuity Turn ignition off. Disconnect PCM from breakout box. Measure resistance between test pin No. 46 at breakout box and SIG RTN terminal at DLC. If resistance is less than 5 ohms, go to «CIRCUIT TEST C»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If resistance is 5 ohms or more, repair open circuit and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
3. Check STI Circuit Continuity Turn ignition off. Disconnect PCM from breakout box. Measure resistance between test pin No. 48 at breakout box and Self-Test Input (STI) terminal at pigtail connector. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If resistance is less than 5 ohms, go to next step.
4. Check STO Circuit Continuity Leave ignition off and PCM disconnected. Measure resistance between test pin No. 17 at breakout box and STO terminal at DLC. If resistance is less than 5 ohms, go to step 5). If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
5. Check HO2S Signal For Short To Power Leave PCM disconnected. Turn ignition on. Measure voltage between test pin No. 40 or 60 and HO2S SIGNAL test pin No. 29 or 44 at breakout box. For HO2S circuit schematics, see «CIRCUIT TEST H»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__circuit-test-h-fuel-control) . If voltage is more than 2 volts, go to step 6). If voltage is 2 volts or less, go to step 7).
6. Isolate Short To Harness Or HO2S Sensor Turn ignition off. Leave PCM disconnected. Disconnect right/rear HO2S sensor connector. Turn ignition on. Measure voltage between HO2S SIGNAL test pin No. 29 or 44 and test pin No. 40 or 60 at breakout box. If any reading is more than 2 volts, repair short to power in HO2S SIGNAL circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If voltage is 2 volts or less, replace right/rear HO2S sensor. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
7. Check STO Circuit For Short To Ground Turn ignition off. Leave PCM disconnected. Measure resistance between STO at DLC and engine ground. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in STO or MIL circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
8. Check If Power Relay Is Always On Leave ignition off and PCM disconnected. Connect DVOM between test pin No. 37 or 57 and test pin No. 40 or 60 at breakout box. Turn ignition on and then off. Wait 10 seconds. If voltage changes from more than 10.5 volts to less than 1.0 volt, go to step 10). If voltage does not change from more than 10.5 volts to less than 1.0 volt, go to next step.
9. Check VPWR Circuit For Short To Power Turn ignition off. Leave PCM disconnected. Disconnect EEC power relay or Constant Control Relay Module (CCRM). Connect DVOM to test pin No. 37 or 57 and test pin No. 40 or 60 at breakout box. If voltage is more than 1.0 volt, repair VPWR circuit for a short to power. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If voltage is 1.0 volt or less, replace EEC power relay or CCRM. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
10. Check Malfunction Indicator Light (MIL) Function If MIL is always on, go to CIRCUIT TEST ML, step 1). If MIL is always off, go to CIRCUIT TEST ML, step 2). If MIL is flashing, go to CIRCUIT TEST ML, step 15). If MIL is working normally, replace PCM and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .

A right/rear HO2S shorted to power could prevent EEC system from entering self-diagnostics.

Perform this test when directed by QUICK TEST. This test is intended to diagnose

1. Faulty Powertrain Control Module (PCM).
2. KAPWR wiring harness circuits.

KAPWR Circuit Schematic. Scheme 63

TEST PIN NO. 1 (KAPWR) WIRE COLOR IDENTIFICATION

Continuous Memory Code 512 may be displayed when power between PCM and KAPWR is interrupted. This code may be set when a breakout box is installed or battery is disconnected.

1. Continuous Memory Code 512: Check KAPWR Circuit Voltage Code 512 indicates PCM power interruption in Keep-Alive Memory (KAM). Turn ignition off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure voltage between test pin No. 1 and test pin No. 40 or 60 at breakout box. Observe DVOM while wiggling small sections of EEC wiring harness from PCM to dash. If voltage is less than 10.5 volts, repair open circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If reading is 10.5 volts or more, go to next step.
2. Inspect Wiring Harness Routing Ensure EEC wiring is not routed close to ignition components and secondary ignition wires. If necessary, reroute EEC wiring. Clear codes, and wait 5 minutes. Repeat «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) . If Continuous Memory Code 512 is not repeated, service other codes as necessary. If no other codes are present, testing is complete. If Continuous Memory Code 512 is still present, replace PCM and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .

Perform this circuit test when directed by other CIRCUIT TESTS. This test is only intended to diagnose

1. Throttle plate linkage.
2. Test conditions.

1. Check For Codes 121, 122 & 123 Disconnect cruise control servo wiring harness connector (if equipped). Perform «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) . If Code 121, 122 or 123 is present, go to appropriate CIRCUIT TEST. See «DIAGNOSTIC TROUBLE CODE REFERENCE CHARTS»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) , and service codes as necessary. If Code 111 (pass code) is displayed, go to next step. If no code is displayed, go to «CIRCUIT TEST QA»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
2. Check Throttle Linkage Check throttle and linkage for sticking and binding. If throttle and linkage are okay, replace Throttle Position (TP) sensor and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If throttle or linkage is binding, repair as necessary and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .

Perform this test only when directed by QUICK TEST. This test is intended to diagnose

1. Battery voltage.
2. Powertrain Control Module (PCM).

1. Code 513 Code 513 indicated PCM internal voltage is not to specification. Possible causes for this fault are: Low battery voltage. Faulty PCM. Turn ignition off. Measure voltage between battery terminals. If voltage is more than 10.5 volts, replace PCM and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If voltage is 10.5 volts or less, service charging system as necessary. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .

Perform this test only when directed by CIRCUIT TEST AA, CIRCUIT TEST AB or CIRCUIT TEST AC . This test is intended to diagnose

1. IAC system.
2. EGR system.

1. 1) IAC Check Try to start engine at part throttle. If engine starts and runs smoothly at part throttle, go to «CIRCUIT TEST KE»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) , step 4). If engine does not run as described, go to step 3). If engine starts and idles smoothly, go to next step.
2. 2) Check For RPM Drop Turn ignition off. Connect a tachometer to engine. Start engine. Disconnect IAC solenoid. If RPM drops or engine stalls, reconnect IAC solenoid and go to step 8). If RPM does not drop, «CIRCUIT TEST KE»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) , step 4). NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 2) to step 8). No test procedures have been omitted.
3. 8) Check EGR Vacuum If vehicle is not equipped with EGR system, go to CIRCUIT TEST H, step 2). If vehicle is equipped with EGR, disconnect and plug vacuum line at EGR valve. Attempt to start engine. If vehicle could not start previously and still does not start or if vehicle driveability fault is still present, go to next step. If vehicle did not start previously but starts now or if driveability symptoms are eliminated, go to one of the following: Models with Differential Pressure Feedback EGR (DPFE), go to «CIRCUIT TEST DL»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) , step 50). Models with Pressure Feedback EGR (PFE), go to «CIRCUIT TEST DL»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) , step 21). On all other models, go to «CIRCUIT TEST DN»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) , step 42).
4. 9) Check EGR Valve Inspect EGR valve for leaks. If valve is fully closed, go to «CIRCUIT TEST H»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__circuit-test-h-fuel-control) , step 2). If EGR valve is leaking or is not fully seated, repair or replace valve as necessary.

Perform this test only when directed by QUICK TEST. This test is intended to diagnose

1. Clutch Pedal Position (CPP) switch.
2. Park/Neutral Position (PNP) switch.
3. Powertrain Control Module (PCM).
4. Wiring harness circuits (CPP, PNP and SIG RTN). TEST PIN WIRE COLOR IDENTIFICATION Application Wire Color TEST PIN NO. 30 (CPP/PNP) Light Blue/Yellow TEST PIN NO. 46 (SIG RTN) Gray/Red

Scheme 64

Scheme 65

1. 1) Code 522, 525 Or 528 Code 522, 525 or 528 is a result of voltage being high at pin No. 30 (CPP/PNP input) while cranking engine or during KOEO SELF-TEST. Possible causes for these faults are: CPP or PNP circuit open. Faulty Powertrain Control Module (PCM). Starter relay disconnected during self-test. On A/T models, go to step 8). On M/T models, go to step 2).
2. 2) Check CPP/PNP Input Turn ignition off. Turn A/C off (if equipped). Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pins No. 30 and 46 with transmission in Neutral and clutch pedal up. Also, measure resistance between test pins No. 30 and 46 with transmission in gear and clutch pedal down. If each resistance is less than 5 ohms, go to next step. If any resistance is 5 ohms or more, go to step 5). (Scheme 64): Identifying Neutral Gear/Clutch Input Circuit
3. 3) Check CPP/PNP Switch Integrity Leave ignition off and PCM disconnected. Measure resistance between test pins No. 30 and 46 with transmission in any gear and clutch pedal up. If resistance is less than 5 ohms, replace PCM and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If resistance is 5 ohms or more, go to next step.
4. 4) Check For CPP Short To Ground Leave ignition off and PCM disconnected. Disconnect CPP switch. Measure resistance between test pins No. 30 and 46. If resistance is more than 10,000 ohms, replace PCM and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If resistance is 10,000 ohms or less, repair short circuit. Reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
5. 5) Check PNP & CPP Switches Leave ignition off and PCM disconnected. Locate PNP switch (on transmission) and CPP switch (at clutch pedal linkage). Disconnect wiring harness at both switches. Measure resistance between PNP switch terminals with transmission in Neutral. Also, measure resistance between CPP switch terminals with clutch pedal down. If each resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, replace switch. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
6. 6) Check Neutral Gear/Clutch Harness Leave ignition off and PCM disconnected. Measure resistance between test pin No. 30 and the following terminals: PNP switch wiring harness connector terminal CPP and/or PNP. CPP switch wiring harness connector terminal CPP and/or PNP. Measure resistance between test pin No. 46 and the following terminals: PNP switch wiring harness connector terminal SIG RTN. CPP switch wiring harness connector terminal SIG RTN. If any resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If each resistance is less than 5 ohms, replace PCM and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
7. 7) Check CPP Switch Turn ignition and A/C off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pins No. 30 and 46 at breakout box. If resistance is less than 5 ohms, replace PCM and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If each resistance is 5 ohms or more, repair open circuit. Reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
8. 8) Check PNP Input Turn ignition and A/C off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect PCM to breakout box. Ensure transmission is in Neutral or Park. Turn ignition on. Measure voltage between test pin No. 30 and chassis ground. If voltage is less than 1.0 volt, replace PCM and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If voltage is 1.0 volt or more, go to next step.
9. 9) Check PNP Switch Resistance Turn ignition off. Disconnect PCM from breakout box. Disconnect PNP wiring harness connector. Measure resistance between switch terminals. If resistance is less than 5 ohms, repair open in PNP circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If resistance is 5 ohms or more, replace PNP switch. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 9) to step 15). No test procedures have been omitted.
10. 15) Code 522: Check If Engine Starts KOEO Code 522 indicates that high voltage was sensed at test pin No. 30 during SELF-TEST. Possible causes for this fault are: Engine Starts: Transmission not in Park during SELF-TEST. Open PNP circuit between PCM and connection to START circuit. PNP/START circuit shorted to power Faulty PCM. No Start: Faulty starter relay. Open in START circuit between PNP switch and PNP connection to circuit, PNP switch and starter relay or starter relay and ground. Verify transmission was in Park during SELF-TEST. If transmission was not in Park, repeat SELF-TEST. If transmission was in Park, try to start engine. If engine starts, go to next step. If engine does not start, fault is in starter circuit. Repair as necessary.
11. 16) Check For Short To Power In PNP/START Circuit Turn ignition off. Disconnect PCM 60-pin connector. Inspect for damage, and repair if necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Turn ignition on. Measure voltage between test pins No. 30 and 40 (GND) at breakout box. If voltage is less than 0.5 volt, turn ignition off and go to next step. If voltage is 0.5 volt or more, repair short to power. Remove breakout box and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
12. 17) Check PNP Circuit Continuity Disconnect PNP 3-pin connector at transmission. Measure resistance between test pin No. 30 at breakout box and PNP/IGN START terminal at PNP switch vehicle wiring harness connector. If resistance is less than 5 ohms, replace PCM. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If resistance is 5 ohms or more, repair open circuit between PCM and PNP circuit connection to START circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). (Scheme 65): Identifying PNP/IGN START Circuit

Perform this test only when directed by QUICK TEST. This test is intended to diagnose

1. Powertrain Control Module (PCM).
2. Wiring harness circuits (TCIL, TCS).

To prevent replacing good components, be aware the following non-EEC related areas may be at fault

1. Basic engine condition (valves, vacuum leaks, valve timing, etc.).
2. Charging system.
3. Transmission (fluid, friction elements and cooling).

Transmission Control Switch (TCS) allows driver to disengage overdrive. TCS is located on transmission shift knob. TCIL is located in instrument cluster.

TEST PIN WIRE COLOR IDENTIFICATION

Note. Procedure starts at step 2). No test procedures have been omitted.

1. 2) Code 632 Or 653 Code 632 or 653 indicates that the TCS was not cycled between engine ID Code and WOT check during KOER SELF-TEST. Possible causes for this fault are: Faulty TCS or switch was not cycled during SELF-TEST. Shorted wiring harness. Faulty Powertrain Control Module (PCM). Open in wiring harness or fuse. If TCS was cycled during KOER SELF-TEST, go to step 4). If TCS was not cycled during KOER SELF-TEST, repeat «KOER SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) while cycling TCS.
2. 3) Code 623 Or 631 Code 623 or 631 indicates transmission control indicator light circuit fault during KOEO SELF-TEST. Possible causes for this fault are: Burned out bulb. Open or shorted wiring harness. If TCS was cycled during KOEO SELF-TEST, go to step 5). If TCS was not cycled during KOEO SELF-TEST, repeat «KOER SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) while cycling TCS.
3. 4) Check TCS Circuit Turn ignition off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Turn ignition on. Measure voltage between test pin No. 41 and test pin No. 40 or 60 at breakout box while cycling TCS several times. If voltage cycles replace PCM. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If voltage does not cycle, go to next step if diagnosing a trouble code or step 7) if diagnosing a driveability symptom.
4. 5) Check Circuits For Short To Ground Turn ignition off. Leave PCM disconnected from breakout box. Disconnect TCS connector. Inspect connector for damage and repair as necessary. Measure resistance between test pin No. 41 and test pin 40 or 60. Also, measure resistance between test pin No. 55 and test pin No. 40 or 60. If each reading is more than 10,000 ohms, go to next step (Code 623 or 631) or step 8) (Code 632 or 653). If any reading is 10,000 ohms or less, repair short circuit. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If code is still present, go to step 7).
5. 6) Check Power Through TCIL Circuit Turn ignition off. Leave PCM disconnected from breakout box. Measure voltage between test pin No. 55 and test pin No. 40 or 60. If voltage is more than 10.5 volts, replace PCM. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If voltage is 10.5 volts or less, go to next step.
6. 7) Check Output Driver Voltage Signal Leave PCM disconnected from breakout box. Turn ignition on. Measure voltage between test pin No. 55 and test pin No. 40 or 60. If voltage is 2 volts or more, go to next step. If voltage is less than 2 volts, check bulb and fuse. Replace as necessary. If bulb and fuse are okay, repair open circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
7. 8) Check Transmission Control Switch Wiring Harness Turn ignition off. Leave PCM disconnected from breakout box. Ensure TCS is disconnected. Measure resistance of Red/Yellow wire between TCS and fuse No. 9 (10-amp) at instrument panel fuse block. Measure resistance of TCS circuit between test pin No. 41 at breakout box and TCS circuit terminal at TCS wiring harness connector. If any reading is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If each reading is less than 5 ohms, go to next step.
8. 9) Check For Short To Power Turn ignition off. Leave PCM disconnected from breakout box. Ensure TCS is disconnected. Measure resistance between test pin No. 41 and test pin No. 37 or 57. Also, measure resistance between test pin No. 55 and test pin No. 37 or 57. If each reading is more than 10,000 ohms, replace TCS switch. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If any reading is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .

Perform this test only when directed by QUICK TEST. To prevent replacing good components, be aware the following non-EEC areas may be at fault

1. Engine condition (compression, cam timing, valves, etc.).
2. Charging system or battery.
3. Transmission linkage, internal components or cooling.

This test is not intended to diagnose transmission. This test is intended to diagnose

Scheme 66

1. Wiring harness circuits TCC, CCS, EPC, SS3/4, SS1, SS2, SS3, SIG RTN, EPC PWR and VPWR.
2. Faulty Powertrain Control Module (PCM). CIRCUIT TEST TC ACRONYMS Acronym Definition CCC Converter Clutch Control CCS Coast Clutch Control EPC Electronic Pressure Control MCCC Modulated Converter Clutch Control SS Shift Solenoid TCC Torque Converter Clutch (Scheme 66): AODE Solenoid Circuits AODE DIAGNOSTIC TROUBLE CODE IDENTIFICATION Application PCM Pin No. KOEO Code EPC 38 624 & 625 SS1 51 621 SS2 52 622 TCC 53 623 & 652 TEST PIN NO. 53 (TCC) WIRE COLOR IDENTIFICATION Application Wire Color Mark VIII Pink/Yellow

1. 1) OUTPUT STATE CHECK Codes 621, 622, 626, 629, 641 and 652 indicates shift solenoid did not respond to PCM command. Possible causes for these faults are: Faulty solenoid assembly. Circuit open or grounded. Faulty Powertrain Control Module (PCM). To enter output state Diagnostic Test Mode (DTM), use only VOM or DVOM. DO NOT use scan tester. Turn ignition off. Disconnect cruise control servo wiring harness connector. Connect DVOM negative lead to STO terminal at Data Link Connector (DLC). Connect positive lead to positive battery terminal. Connect a jumper wire between SIG RTN terminal and STI terminal at DLC. (Scheme 62) Perform «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) until continuous memory test is complete. DVOM will read less than 1.0 volt when test is complete to indicate PCM has entered output state DTM. Depress and release throttle. If voltage increases, remain in output state DTM and go to next step. If voltage does not increase, depress throttle to WOT and release. If STO voltage goes high, go to next step. If STO voltage does not go high, leave test equipment connected and go to «CIRCUIT TEST QC»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
2. Check Solenoid Electrical Condition Turn ignition off. Disconnect transmission wiring harness connector. Inspect terminals, and repair if damaged. Connect VOM or DVOM positive test lead to solenoid wiring harness connector VPWR terminal. Connect negative test lead to appropriate shift solenoid terminal at transmission wiring harness connector. Turn ignition on. Cycle solenoid output on and off by depressing and releasing throttle 3-5 times. If voltage output changes 0.5 volt or more, fault is in transmission. If voltage output does not change 0.5 volt or more, remove jumper wire between SIG RTN terminal and STI terminal at DLC. Go to next step.
3. 3) Check Solenoid & VPWR Circuit Continuity Turn ignition off. Leave transmission wiring harness disconnected. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between suspect signal output terminal at transmission vehicle wiring harness connector terminal and corresponding test terminal at breakout box. See appropriate wiring schematic at beginning of this circuit test. Also, measure resistance between breakout box test pins No. 37 and 57 and VPWR terminal at transmission vehicle wiring harness connector. If each resistance is less than 5 ohms, go to next step. If any resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
4. 4) Check Solenoid Circuit For Short To Power Or Ground Leave ignition off and PCM disconnected. Leave transmission wiring harness disconnected. Measure resistance between suspect solenoid output signal test pin and test pins No. 37 and 57 at breakout box. Also, measure resistance between suspect solenoid output signal test pin and pins No. 40, 46 and 60 at breakout box and chassis ground. Measure resistance between PCM output signal test pin and chassis ground. If any reading is less than 10,000 ohms, repair short circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If all readings are 10,000 ohms or more, check solenoids. If solenoids are okay, replace PCM. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 4) to step 10). No test procedures have been omitted.
5. 10) Code 624 Or 625: Check VPWR To Solenoid Code 624 indicates failure of EPC circuit. Code 625 indicates EPC driver failure. Possible causes for these faults are: Faulty solenoid. Circuit open or grounded. Turn ignition off. Disconnect transmission wiring harness connector. Turn ignition on. Measure voltage between VPWR and EPC PWR terminal at transmission wiring harness connector and chassis/battery ground. If voltage is less 10.5 volts or less, repair open circuit. Reconnect all components and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If voltage is more than 10.5 volts, go to next step.
6. 11) Check Solenoid Signal & VPWR Circuit Continuity Turn ignition off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between VPWR/EPC PWR terminal at transmission wiring harness connector breakout box test pins No. 37 and 57. Also, measure resistance between test pin No. 38 at breakout box and EPC terminal at transmission wiring harness connector. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If resistance is less than 5 ohms, go to next step.
7. 12) Check Circuit For Short To Power Or Ground Leave ignition off and PCM disconnected. Leave transmission wiring harness connector disconnected. Measure resistance between test pins No. 37 and 57 and suspect solenoid test pin at breakout box. Also, measure resistance between test pins No. 40, 46 and 60 and suspect solenoid test pin at breakout box. If any reading is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If all readings are more than 10,000, check solenoids. If solenoids are okay, replace PCM. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 12) to step 20). No test procedures have been omitted.
8. 20) Code 621, 622, 641 Or 643: Check Solenoid Resistance KOEO Code 621 (SS1), 622 (SS2), 641 (SS3) or 643 (TCC) indicate failure in shift solenoid circuit. Possible causes for these faults are: Faulty shift solenoid. Circuit open or grounded. Faulty PCM. Turn ignition off. Disconnect transmission wiring harness connector. Measure resistance between suspect shift solenoid at transmission wiring harness connector and chassis ground. If resistance is 13-27 ohms, go to next step. If resistance is not 13-27 ohms, go to step 25).
9. 21) Check Shift Solenoid For Short To Power Leave ignition off and transmission wiring harness connector disconnected. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Turn ignition on. Measure voltage between suspect shift solenoid at transmission wiring harness connector and chassis ground. If voltage is 0.5 volt or more, repair short to power and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If voltage is less than 0.5 volt, go to next step.
10. 22) Check Shift Solenoid For Short To Ground Turn ignition off. Leave transmission wiring harness connector disconnected. Measure resistance between suspect shift solenoid at transmission wiring harness connector and chassis ground. Also, measure resistance between suspect shift solenoid and other circuits at transmission wiring harness connector. If any reading is 10,000 ohms or less, repair short circuit. Reconnect all components and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If all readings are more than 10,000 ohms, go to next step.
11. 23) Check Shift Solenoid Circuit Continuity Turn ignition off. Leave transmission wiring harness connector disconnected. Install EEC-IV Breakout Box (T83L-50-EEC-IV) or 4EAT tester, leaving PCM disconnected. Measure resistance between suspect shift solenoid test pin at breakout box and suspect shift solenoid terminal at transmission wiring harness connector. If resistance is 5 ohms or more, repair open circuit. Reconnect all components and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If resistance is less than 5 ohms, go to next step.
12. 24) Check Shift Solenoid For Short To Power In Transmission Leave ignition off and PCM disconnected. Reconnect transmission wiring harness connector. Measure voltage between test pin No. 60 and suspect shift solenoid test pin at breakout box. If voltage is 0.5 volt or more, replace or repair solenoid for a short to power (within transmission). Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If voltage is less than 0.5 volt, replace PCM. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
13. 25) Check Transmission Wiring Leave ignition off. Check transmission wiring harness circuits and connectors breaks or corrosion in insulation. Check for open or grounded circuits. Repair or replace wiring as necessary. If connectors and circuits are okay, replace suspect solenoid and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 25) to step 30). No test procedures have been omitted.
14. 30) Continuous Memory Codes 621, 622, 641 & 643 Continuous Memory Code 621 (SS1), 622 (SS2), 641 (SS3) or 643 (TCC) indicates a failure was detected in shift solenoid circuit during last 80 warm-up cycles. Possible causes for these faults are: Faulty shift solenoid. Circuit open or grounded. Turn ignition off. Check shift solenoid circuit between PCM and transmission. Repair or replace wiring as necessary. If circuits are okay, go to next step.
15. 31) Check For Intermittent Short Or Open Turn ignition off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV) or 4EAT tester, leaving PCM disconnected. Turn ignition on. Connect test light between test pin No. 37 and suspect shift solenoid test pin at breakout box. See «IDENTIFYING SHIFT SOLENOID TEST CIRCUITS»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) table. Test light should be at partial brightness. Observe test light while wiggling and bending shift solenoid circuit between transmission and PCM. An open or short to power will be indicated by light going off. A short to ground will be indicated by light getting brighter. Repeat procedure for all solenoids. If fault is indicated, isolate and repair as necessary. If no fault is indicated, go to next step. IDENTIFYING SHIFT SOLENOID TEST CIRCUITS Shift Solenoid Test Pin No. SS1 11 SS2 51 SS3 52 CCC 55
16. 32) Check For Intermittent Short To Ground Leave ignition off and PCM disconnected. Disconnect transmission wiring harness connector. Turn ignition on. Connect test light between test pin No. 37 and suspect shift solenoid test pin at breakout box. See «IDENTIFYING SHIFT SOLENOID TEST CIRCUITS»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) table. Test light should be off. Observe test light while wiggling and bending shift solenoid circuit between transmission and PCM. A short to ground will be indicated by light turning on. Repeat procedure for all solenoids. If fault is indicated, isolate and repair as necessary. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If no fault is indicated, problem is intermittent and cannot be duplicated at this time.

Perform this test only when directed by QUICK TEST. To prevent replacing good components, be aware the following non-EEC areas may be at fault

1. Transmission linkage and internal components.
2. Electrical (alternator, battery, add-on devices, etc.).

This test is not intended to diagnose transmission. This test is intended to diagnose

1. Wiring harness circuits TR, TRD, TRL, TRR, TROD and SIG RTN.
2. Powertrain Control Module (PCM).

Transmission range sensor may also be known as transmission range switch.

Identifying TR Sensor Circuits (AODE). Scheme 67

1. 1) Codes 522, 634, 654, 667 & 668: Check TR Sensor Alignment KOEO Code 634 indicates TR sensor is out of self-test range (3770-4607 ohms) when gear selector is in Park position. KOEO Codes 522 and 654 indicate gear selector was not in Park position during self-test. KOEO Code 667 indicates a short to ground in TR sensor circuits. KOEO Code 668 indicates an open in TR sensor circuits. Possible causes for these faults are: Transmission range not in Park during SELF-TEST. Linkage not adjusted correctly. Faulty TR sensor. Circuit open or shorted. Faulty Powertrain Control Module (PCM). Turn ignition off. Apply parking brake. Check TR sensor adjustment. Adjust sensor as necessary. See ADJUSTMENTS in the TRANSMISSION SERVICING - A/T article. If sensor is adjusted properly, go to next step.
2. 2) Check TR Sensor Circuit Continuity Turn ignition off. Disconnect TR sensor wiring harness connector. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between TR terminal at TR sensor wiring harness connector and test pin No. 30 at breakout box. Also, measure resistance between SIG RTN terminal at TR sensor wiring harness connector and test pin No. 46 at breakout box. If any reading is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If both readings are less than 5 ohms, go to next step.
3. 3) Check TR Sensor For Short To Power & Ground Turn ignition off. Leave PCM and TR sensor disconnected. Measure resistance between test pin No. 30 and test pins No. 37, 40, 46, 57 and 60 at breakout box. Also, measure resistance between test pin No. 30 and chassis ground. If any reading is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If resistance is more than 10,000 ohms, go to next step.
4. 4) Check TR Sensor Resistance Turn ignition off. Connect TR sensor. Leave PCM disconnected. Unlock steering column. Measure resistance between test pins No. 30 and 46 at breakout box while cycling gear selector. See «TR SENSOR RESISTANCE»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) table. If resistance is within specification, replace PCM and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If resistance is not within specification, replace TR sensor and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . TR SENSOR RESISTANCE Gear Selected Ohms Park 3770-4607 Reverse 1304-1593 Neutral 660-807 Overdrive 361-442 Drive 190-232 First 78-95 NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 4) to step 9). No test procedures have been omitted.
5. 9) Transmission In Third Gear Only While in D/OD Ensure transmission fluid is at correct level and in good condition. Test drive vehicle with shift lever in both D and OD positions. If transmission always remains in 3rd gear when vehicle is operated with shift lever in D or OD position, go to step 11). If transmission sometimes shifts okay, go to step 20).
6. 10) Continuous Memory Code 634 Code 634 indicates PCM has received incorrect voltage signals from PNP switch. Test drive vehicle with shift lever in both D and OD positions. If transmission always remains in 3rd gear when vehicle is operated with shift lever in D or OD position, go to next step. If transmission sometimes shifts okay, go to step 20).
7. 11) Check IGN START/RUN Circuit At Transmission Turn ignition off. Disconnect 4EAT wiring harness connector at transmission. Turn ignition on. Measure voltage between IGN START/RUN terminal at transmission wiring harness connector and chassis ground. If voltage is 10.5 volts or less, repair open circuit and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If voltage is more than 10.5 volts, go to next step.
8. 12) Check Transmission Select Switches Leave ignition off and 4EAT wiring harness connector disconnected. Disconnect 3-pin inhibit (PNP) switch connector at transmission. Check that each switch state resistance is correct for each gear selector position. If any resistance is not correct, go to step 14). If all resistances are correct, go to next step.
9. 13) Check Transmission Switch Input Voltage Turn ignition off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV) or 4EAT tester, leaving PCM disconnected. Reconnect inhibit switch and transmission switch connectors. Turn ignition on. Check that each switch state voltage at breakout box is correct for each gear selector position. If all voltage readings are correct and no other problems can be found, replace PCM and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If any voltage reading is not correct, repair circuit(s) and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
10. 14) Check TR Sensor & Wiring Turn ignition off. Check TR sensor circuits and connectors for damage and corrosion. Repair wiring as necessary. If wiring is okay, ensure TR sensor is adjusted correctly. Adjust sensor as necessary. See ADJUSTMENTS in the TRANSMISSION SERVICING - A/T article. If sensor is adjusted properly, replace TR sensor. Reconnect all components and check system operation. NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 14) to step 20). No test procedures have been omitted.
11. 20) Inspect 4EAT Circuit Turn ignition off. Inspect TR sensor and transmission shift solenoid wires between PCM and transmission for corrosion or damage. Inspect wiring harness for correct routing. If any faults are found, repair or replace as necessary. If no faults are found, go to next step.
12. 21) Check Wiring Harness & Connectors For Intermittent Open Or Short Circuit Turn ignition off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV) or 4EAT tester, leaving PCM disconnected. Turn ignition on. Connect test light between test pin No. 40 and transmission test pin as follows: Test pin No. 18 (TRD) with gear selector in D. Test pin No. 23 (TRR) with gear selector in R. Test pin No. 38 (TROD) with gear selector in OD. Test pin No. 45 (TRL) with gear selector in L. Test light should be on when gear selector is in the same gear as the circuit being tested. Shake and wiggle transmission switch wiring harness between PCM and transmission. Lightly tap on inhibit switch to simulate road shock. If test light dims, flickers or goes off, fault is indicated. Isolate fault and repair as necessary. Remove breakout box, reconnect all components and check system operation. If test light stays on, fault cannot be duplicated at this time. CAUTION: Following road test is an optional procedure. Follow all applicable safety procedures and traffic laws. This road test requires a driver and an assistant. Assistant should make measurements, observe changes and record notes. If this test is not performed, go to the «TESTS W/O CODES»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wo-codes) article for other possible causes.

Perform this test only when directed by QUICK TEST. To prevent replacing good components, be aware the following non-EEC areas may be at fault

1. Engine and/or transmission fluid level.
2. Engine and/or transmission fluid temperature.
3. Ambient temperature.

This test is intended to diagnose

1. TFT sensor.
2. Wiring harness circuits TFT and SIG RTN.
3. Faulty Powertrain Control Module (PCM). TFT SENSOR SPECIFICATIONS Temperature °F (°C) (1) Volts (1) Ohms 32 (0) 3.88 96,255 59 (15) 3.32 46,883 104 (40) 2.15 16,043 158 (60) 1.03 5260 194 (90) 0.60 2750 (1) Values may vary by 15 percent.

1. 1) KOEO Code 636 KOEO Code 636 indicates TFT sensor is out of self-test range. Possible causes for these faults are: Transmission fluid level incorrect. Transmission fluid temperature incorrect. Sensor resistance out of specification. Faulty Powertrain Control Module (PCM). Ensure transmission fluid temperature is more than 50°F (10°C). Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If Code 636 is present, go to next. If Code 636 is not present, no problem is indicated at this time. Test is complete.
2. 2) Check VREF At Throttle Position (TP) Sensor Turn ignition off. Disconnect TP sensor wiring harness connector. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect PCM to breakout box. Turn ignition on. Measure voltage between VREF and SIG RTN terminals at TP sensor wiring harness connector. If voltage is 4-6 volts, go to next step. If voltage is not 4-6 volts, go to «CIRCUIT TEST C»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
3. 3) Check TFT Sensor Resistance Turn ignition off. Disconnect PCM from breakout box. Allow transmission to cool. Measure and record resistance between test pin No. 46 and TFT test pin at breakout box. Reconnect PCM. Drive vehicle until transmission fluid is normal operating temperature. Disconnect PCM from breakout box. Again, measure resistance between test pin No. 46 and TFT test pin at breakout box. If cold resistance measurement is greater than warm resistance measurement, and warm resistance is within specification, replace PCM and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . See appropriate TFT SENSOR SPECIFICATIONS table at beginning of this circuit test. If resistance is not as specified, service TFT sensor. NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 3) to step 10). No test procedures have been omitted.
4. 10) KOEO Code 637 KOEO Code 637 indicates TFT sensor output exceeds self-test maximum voltage (4.8 volts). Possible causes for these faults are: Transmission fluid level incorrect. Open wiring harness circuit. Faulty TFT sensor. Faulty PCM. Turn ignition off. Disconnect transmission connector. Inspect terminals, and repair if damaged. Connect jumper wire between TFT and SIG RTN terminals at transmission vehicle wiring harness connector. Perform «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) . If Code 638 is present, remove jumper wire and service TFT sensor. If Code 638 is not present, remove jumper wire and go to next step.
5. 11) Check TFT & SIG RTN Circuit Continuity Turn ignition off. Leave transmission connector disconnected. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between TFT circuit at transmission vehicle wiring harness connector and TFT test pin at breakout box. Also, measure resistance between SIG RTN circuit at transmission vehicle wiring harness connector and test pin No. 46 at breakout box. If any reading is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If all readings are less than 5 ohms, go to next step.
6. 12) Check TFT Sensor For Short To VPWR Turn ignition off. Leave PCM and transmission connector disconnected. Measure resistance between TFT test pin and test pins No. 37 and 57 at breakout box. If all readings are more than 10,000 ohms, replace PCM. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If any reading is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 12) to step 20). No test procedures have been omitted.
7. 20) KOEO Code 638 KOEO Code 638 indicates TFT sensor output is lower than self-test minimum voltage. Possible causes for these faults are: Damaged TFT sensor. Shorted wiring harness circuit. Faulty PCM. Turn ignition off. Disconnect transmission wiring harness connector. Inspect terminals, and repair if damaged. Perform «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) with transmission connector disconnected. If Code 637 is present, service TFT sensor. If Code 637 is not present, go to step 21).
8. 21) Check VREF At Throttle Position (TP) Sensor Turn ignition off. Disconnect TP sensor wiring harness connector. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect PCM to breakout box. Turn ignition on. Measure voltage between VREF and SIG RTN terminals at TP sensor vehicle wiring harness connector. If voltage is 4-6 volts, go to next step. If voltage is not 4-6 volts, go to «CIRCUIT TEST C»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
9. 22) Check TFT Circuit For Short To Ground Turn ignition off. Disconnect PCM from breakout box. Measure resistance between TFT test pin at breakout box and test pins No. 40, 46 and 60. If all readings are more than 10,000 ohms, replace PCM. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If any reading is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 22) to step 25). No test procedures have been omitted.
10. 25) Check Transmission Wiring Harness Turn ignition off. Check transmission internal and external wiring and connectors for damage and corrosion. Repair or replace as necessary and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If wiring is okay, replace TFT sensor and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 25) to step 90). No test procedures have been omitted.
11. 90) Continuous Memory Code 637 Or 638 Continuous Memory Code 637 or 638 indicates a fault has been detected in TFT circuit during previous 80 warm-up cycles. Possible causes for these faults are: Incorrect fluid level. Intermittent fault in TFT sensor. Intermittent short or open in wiring harness. Turn ignition off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect PCM to breakout box. Connect DVOM between test pins No. 2 and 46 at breakout box. Turn ignition on. Note DVOM voltage reading. Shake and bend TFT and SIG RTN wires between transmission and PCM. Voltage should remain stable or change gradually. If voltage drops to zero, a short to ground is indicated. If voltage increases up to 5 volts, an open circuit is indicated. If voltage increases to more than 5 volts, a short to power is indicated. If fault is indicated, isolate and repair as necessary. If no faults are found, go to «CIRCUIT TEST TD»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) , step 22). NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 90) to step 100). No test procedures have been omitted.
12. 100) Continuous Memory Code 657 Continuous Memory Code 657 indicates excessive transmission temperatures. Possible causes for these faults are: Damage in transmission cooling system. Pulling overweight trailer. Incorrect fluid level. Damaged clutch. Fault in TFT sensor. Intermittent short or open in wiring harness. Turn ignition off. Disconnect transmission wiring harness connector. Inspect terminals, and repair if damaged. Reconnect transmission connector. Perform «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test) . If no code(s) is present, fault is in transmission. If Code 657 is present, fault is in transmission. If any other code(s) is present, service as necessary and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .

Perform this test only when directed by QUICK TEST. To prevent replacing good components, be aware the following non-EEC areas may be at fault

1. Transmission fluid level.
2. Engine/transmission fluid temperature.
3. Ambient temperature.
4. Aftermarket modifications.
5. Engine sensors.
6. Faulty wiring harness connectors.

This test is intended to diagnose

Scheme 68

1. Wiring harness circuits CCS, SS1, SS2, SS3, EPC, TCC, TFT, TR and 3-2/CC3.
2. Powertrain Control Module (PCM) (Scheme 68): Identifying A0DE Electronic Transmission Circuits TEST PINS NO. 30 (TR) & 53 (TCC) WIRE COLOR ID Application Test Pin No. Wire Color Mark VIII 53 Purple/Yellow Mark VIII 30 Light Blue/Yellow NOTE: Procedure begins with step 90). No test procedures have been omitted.

1. 90) Perform Drive Cycle Test Ensure all components are connected. Ensure transmission fluid is correct level. Warm engine to normal operating temperature. Perform «KOER SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) and CONTINUOUS MEMORY CODE SELF-TEST. Clear all codes. Perform appropriate DRIVE CYCLE TEST.
2. 91) Code 624, 634 Or 651 Code 624 and 651 indicate Electronic Pressure Control (EPC) failure. Code 634 indicates that Transmission Range (TR) sensor is out of calibration. Possible causes for these faults are: Faulty EPC solenoid. Faulty TR sensor. Circuit open or grounded. Damaged PCM connector pins. Turn ignition off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect PCM to breakout box. To test EPC solenoid, connect DVOM between EPC test pin and EPC VPWR test pin at breakout box. To test TR sensor, connect DVOM between TR test pin and test pin No. 46 at breakout box. For EPC solenoid or TR sensor, turn ignition on. Voltage for EPC should be less than 10 volts. Voltage for TR should be less than 5 volts with transmission in Park. Shake and bend EPC/TR wiring harness. Lightly tap on components to simulate road shock. Voltage should remain stable. If voltage changes or exceeds specification, fault in circuit is indicated. If fault is indicated, isolate fault and repair as necessary. Clear continuous memory codes, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If no faults are found, problem cannot be located at this time.
3. 92) Check Circuit Harness & Connectors Enter CONTINUOUS MONITOR MODE. Shake and bend EEC wiring harness while observing analog VOM or scan tool. Lightly tap on components to simulate road shock. If VOM indicator has erratic movement or scan tool beeps, fault is indicated. If fault is indicated, isolate and repair as necessary. Clear continuous memory codes, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If no faults are found, problem cannot be located at this time. CIRCUIT TEST KOEO CONTINUOUS MEMORY CODES Code Fault 617 Improper 1-2 Shift 618 Improper 2-3 Shift 619 Improper 3-4 Shift 628 Excessive Converter Clutch Slippage 637 Excessive TFT Circuit Voltage 638 Inadequate TFT Circuit Voltage 645 Inadequate 1st Gear Command Response 646 Inadequate 2nd Gear Command Response 647 Inadequate 3rd Gear Command Response 648 Inadequate 4th Gear Command Response 656 Continuous Slippage Detected
4. 93) Check For Code 659 Code 659 indicates high vehicle speed detected while vehicle was in Park. Possible causes for this fault are: Faulty Transmission Range (TR) sensor. Faulty Powertrain Control Module (PCM). If Code 659 was present after performing drive cycle test in step 90), go to step 103). If Code 659 was not present after performing drive cycle test in step 90), go to next step.
5. 94) Check For Code 675 Code 675 indicates TR circuit voltage was out of range. Possible causes for this fault are: Faulty TR sensor. Open or short circuit. Short to power or ground in SIG RTN circuit. Faulty Powertrain Control Module (PCM). If Code 675 was present after performing drive cycle test in step 90), go to next step. If Code 675 was not present after performing drive cycle test in step 90), go to step 98).
6. 95) Check For Codes 675 & 667 Code 667 indicates TR circuit voltage was less than self-test minimum voltage allowed. Possible causes for this fault are: Faulty TR sensor. Open or short in TR circuit. Short to power in TR circuit. Faulty Powertrain Control Module (PCM). If Codes 675 and 667 were present after performing drive cycle test in step 90), go to step 99). If Codes 675 and 667 were not present after performing drive cycle test in step 90), go to next step.
7. 96) Check For Codes 675 & 668 Code 668 indicates TR circuit voltage was more than self-test maximum voltage allowed. Possible causes for this fault are: Faulty TR sensor. Open TR circuit. Short to power in SIG RTN circuit. Faulty Powertrain Control Module (PCM). If Codes 675 and 668 were present after performing drive cycle test in step 90), go to step 101). If Code 675 and 668 were not present after performing drive cycle test in step 90), go to next step.
8. 97) Check TR Alignment Turn ignition off. Apply parking brake. Place transmission gear selector in Neutral position. Check TR sensor adjustment. See ADJUSTMENTS in the TRANSMISSION SERVICING - A/T article. Adjust sensor as necessary, clear codes and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If sensor is adjusted properly, go to next step.
9. 98) Check For Code 667 Code 667 indicates TR circuit voltage less than self-test minimum voltage allowed. Possible causes for this fault are: Faulty TR sensor. Open or short to ground in TR circuit. Faulty Powertrain Control Module (PCM). If Code 667 was present after performing drive cycle test in step 90), go to next step. If Code 667 was not present after performing drive cycle test in step 90), go to step 101).
10. 99) Check TR Circuit Resistance Turn ignition off. Disconnect 60-pin PCM connector. Disconnect TR sensor. Inspect connectors for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pin No. 30 at breakout box and TR terminal at TR sensor connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
11. 100) Check For Shot To Ground In TR Circuit Turn ignition off. Ensure breakout box is installed and TR sensor and PCM are disconnected. Measure resistance between test pin No. 30 and chassis ground. If resistance is more than 10,000 ohms, go to step 103). If resistance is 10,000 or less, repair short circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
12. 101) Code 668 Code 668 indicates TR circuit voltage was more than self-test maximum voltage allowed. Possible causes for this fault are: Faulty TR sensor. Open TR circuit. Faulty TR sensor circuit. Faulty Powertrain Control Module (PCM). Turn ignition off. Disconnect 60-pin PCM connector. Disconnect TR sensor. Inspect connectors for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pins No. 46 at breakout box and SIG RTN terminal at TR sensor connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
13. 102) Check For Short To Power Ensure PCM and TR sensor are disconnected. Measure resistance between test pin No. 30 and test pins No. 37, 40, 46, 57 and 60 at breakout box. If all readings are more than 10,000 ohms, go to next step. If any reading is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) .
14. 103) Check TR Sensor Resistance Turn ignition off. Connect TR sensor. Leave PCM disconnected. Unlock steering column. Measure resistance between test pins No. 30 and 46 at breakout box while cycling gear selector. See «TR SENSOR RESISTANCE»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) table. If resistance is within specification, replace PCM and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . If resistance is not within specification, replace TR sensor and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) . TR SENSOR RESISTANCE Gear Selected Ohms Park 3770-4607 Reverse 1304-1593 Neutral 660-807 Overdrive 361-442 2/Drive 190-232 First 78-95

Drive Cycle Test (AODE, CD4E)

With transmission gear selector in Drive position, press Transmission Control Switch (TCS). Transmission Control Indicator Light (TCIL) should come on. Moderately accelerate vehicle to 40 MPH for at least 15 seconds (30 seconds above 4000 ft. elevation). Transmission should be in 3rd gear. While holding speed steady, press TCS. TCIL should go off. Accelerate from 40 MPH to 50 MPH. Transmission should shift from 3rd gear to 4th gear. Hold speed steady for 15 seconds. While holding speed steady, lightly apply and release brakes to turn brakelights on. Maintain 50 MPH for about 5 seconds. Brake to a stop and remain stopped for a minimum of 20 seconds with transmission gear selector in Drive position. Repeat procedure 5 times. After completing drive cycle test, perform KOER SELF-TEST and CONTINUOUS MEMORY CODE SELF-TEST. If Code 111 is present, fault cannot be duplicated at this time. If Code 624, 634 or 651 is present, go to next step. If Code 452 is present, go to CIRCUIT TEST DP. If Code 659, 667, 668 or 675 is present, go to step 93). If any other code(s) is present, go to step 92).

VCRM interfaces with the EEC-IV system to provide control for cooling fan,A/C clutch and A/C head pressure. VCRM also supplies VPWR to EEC-IV system and PCM.

Perform this test only when instructed by QUICK TEST or directed by other test procedures. VCRM is located in left front of vehicle behind front grille. This test is only intended to diagnose following.

1. Variable Control Relay Module (VCRM).
2. Powertrain Control Module (PCM).
3. Harness Circuits Associated With VCRM.

Refer to illustration for VCRM connector terminal identification. (Scheme 69) For VCRM terminals and wiring identification, see the WIRING DIAGRAMS article. To prevent replacing good components, be aware that the following unrelated components or systems may be at fault.

Scheme 69

1. Ignition switch, battery cables and ground straps.
2. Alternator and voltage regulator. (Scheme 69): Identifying VCRM Connector Terminals

Scheme 70

Scheme 71

Scheme 72

Scheme 73

Scheme 74

1. 1) Check Battery Supply Power Turn ignition on. Set DVOM on 20-volt scale. Measure voltage across battery terminals. If voltage is less than 10.5 volts, service or replace discharged battery. Check charging system. If voltage is 10.5 volts or more, go to next step.
2. 2) PCM Ground Fault Isolation Ensure ignition is off. Install breakout box, and connect PCM. Set DVOM on 20-volt scale. Measure voltage between positive battery terminal and SIG RTN terminal (Gray/Red wire) at Data Link Connector (DLC). If voltage is more than 10.5 volts and within one volt of reading in step 1), go to step 10). If voltage is not as specified, go to next step.
3. 3) Check Continuity Of SIG RTN Circuit Turn ignition off. With breakout box installed, disconnect PCM. Measure resistance between test pin No. 46 at breakout box and SIG RTN terminal (Gray/Red wire) at DLC. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open SIG RTN circuit. Remove breakout box, and reconnect all components. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
4. 4) Check PCM Ground Circuit Turn ignition off. With breakout box installed and PCM disconnected, measure resistance between negative battery terminal and test pins No. 40 and 60 at breakout box. If both readings are less than 5 ohms, go to next step. If any reading is 5 ohms or more, repair open in ground circuit. Remove breakout box, and reconnect all components. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
5. 5) Check Internal PCM Ground Circuits Turn ignition off. With breakout box installed, reconnect PCM connector. Measure resistance between test pin No. 46 and test pins No. 40 and 60 at breakout box. If each resistance is less than 5 ohms, system tests okay. Remove breakout box. Reconnect PCM, and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If any resistance is 5 ohms or more, replace PCM. Remove breakout box, and reconnect all components. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 5) to step 10). No test procedures have been omitted.
6. 10) Check Continuity Of VPWR Circuit Turn ignition off. With break-out box installed, disconnect PCM connector. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Measure resistance between terminal No. 7 (Red wire) at VCRM wiring harness connector and test pins No. 37 and 57 at breakout box. If each resistance is less than 5 ohms, go to next step. If any resistance is 5 ohms or more, repair open in VPWR circuit between PCM and VCRM. Remove breakout box, and reconnect all components. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
7. 11) Check For B (+) & IGN START/RUN Power To VCRM Turn ignition off. With breakout box installed and PCM and VCRM disconnected, measure voltage between terminal No. 6 (Yellow wire) at VCRM wiring harness connector and negative battery terminal. Record voltage reading. Turn ignition on. Measure voltage between terminal No. 17 (Red/Light Green wire) at VCRM wiring connector and negative battery terminal. If both readings are 10.5 volts or more, go to next step. If any reading is less than 10.5 volts, turn ignition off. Repair open in B (+) or IGN START/RUN circuit. Remove breakout box, and reconnect all components. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
8. 12) Check VCRM Ground (Terminal No. 16) Turn ignition off. With breakout box installed and PCM and VCRM disconnected, measure resistance between terminal No. 16 (Black/Yellow wire) at VCRM connector and negative battery terminal. If resistance is less than 5 ohms, replace VCRM. Remove breakout box, and reconnect all components. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If resistance is 5 ohms or more, repair open ground circuit. Remove breakout box, and reconnect all components. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 12) to step 15). No test procedures have been omitted.
9. 15) Continuous Memory Code 584 Continuous Memory Code 584 indicates VCRM PWR GND circuit is open. This could be due to a hard fault or an intermittent condition. Following are possible causes for this fault. Open VCRM PWR GND circuit. Damaged VCRM. Clear continuous memory. See «CLEARING CODES»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__clearing-codes) under SELF-DIAGNOSTIC SYSTEM. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Perform Key On Engine Off (KOEO) SELF-TEST. If Code 584 is present (hard code), go to next step. If Code 584 is not present (intermittent), go to step 18).
10. 16) Check Continuity Of VCRM PWR GND Circuit Turn ignition off. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Measure resistance between terminal No. 1 (Black wire) at VCRM connector and negative battery terminal. If resistance is less than 5 ohms, replace VCRM. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If resistance is 5 ohms or more, repair open in ground circuit (Black wire). Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 16) to step 18). No test procedures have been omitted.
11. 18) Check VCRM PWR GND Circuit Turn ignition off. Visually inspect VCRM PWR GND circuit (Black wire) between terminal No. 1 at VCRM connector and ground. VCRM circuit is grounded at a weld nut on right side of radiator support. Repair wiring as necessary. Start engine. Turn A/C on. Shake, wiggle and bend VCRM PWR GND circuit between VCRM and circuit's ground point. Also, lightly tap on VCRM to simulate road shock. An open circuit will be indicated by fan speed increasing to 100 percent (open circuit must be present for 5 seconds). If an open circuit is detected, isolate fault and repair as necessary. Clear continuous memory (Code 584 should have been set). Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If an open circuit is not detected, turn A/C and ignition off. Go to next step.
12. 19) Check VCRM PWR GND Circuit (Cont.) Turn ignition off. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Connect a test light between terminals No. 1 (Black wire) and No. 5 (Yellow wire) of VCRM wiring harness connector. Observe test light, and shake, wiggle and bend VCRM PWR GND circuit between VCRM and circuit's ground point at right side of radiator support. Test light will go out if a fault is detected, indicating open circuit. If an open circuit is detected, isolate fault and repair as necessary. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If open circuit is not detected, fault is intermittent and cannot be duplicated at this time. Testing is complete. Reconnect all components.
13. 20) Continuous Memory Code 581 Continuous Memory Code 581 indicates that when cooling fan was activated, power to cooling fan circuit exceeded normal current draw. This could be due to a hard fault or an intermittent condition. Following are possible causes for this fault. Short to ground in power-to-cooling fan circuit. Faulty cooling fan motor. Faulty VCRM Clear continuous memory. See «CLEARING CODES»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__clearing-codes) under SELF-DIAGNOSTIC SYSTEM. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Perform Key On Engine Off (KOEO) SELF-TEST. If Code 581 is present (hard code), go to next step. If Code 581 is not present (intermittent), go to step 24).
14. 21) Check Cooling Fan Motor Clear continuous memory. Disconnect cooling fan motor connector. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Perform Key On Engine Off (KOEO) self-test. If Code 581 is present, go to next step. If Code 581 is not present, replace cooling fan motor. Reconnect all connectors and repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
15. 22) Check For Short To Ground In Cooling Fan Circuit Turn ignition off. Ensure cooling fan motor connector is disconnected. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Measure resistance between Light Blue wire at cooling fan connector and negative battery terminal. If resistance is more than 10,000 ohms, replace VCRM. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If resistance is 10,000 ohms or less, repair short to ground in Light Blue wire. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 22) to step 24). No test procedures have been omitted.
16. 24) Check For Intermittent Short To Ground In Cooling Fan Circuit Turn ignition off. Visually inspect power-to-cooling fan circuit between terminal No. 2 (Light Blue wire) of VCRM connector and cooling fan motor connector. Repair wiring as necessary. Start engine. Turn A/C on. Shake, wiggle and bend power-to-cooling fan circuit between VCRM and cooling fan motor connector. A short to ground will be indicated by cooling fan turning off. Turn A/C and ignition off. If a short to ground is detected, isolate fault and repair as necessary. Clear continuous memory (Code 581 should have been set). Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If a short to ground is not detected, go to next step.
17. 25) Check VCRM Connector & Cooling Fan Circuit Turn ignition off. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Connect a test light between terminals No. 2 (Light Blue wire) and No. 4 (Yellow wire) at VCRM connector. Test light should glow, but not at full brightness. Observe test light, and shake, wiggle and bend power-to-cooling fan circuit (Light Blue wire) near cooling fan. A short to ground is present if test light gets brighter. If a short to ground is detected, isolate fault and repair as necessary. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If a short to ground is not detected, disconnect and inspect cooling fan connector. Clean or repair connector as necessary. With test light still connected between terminals No. 2 and 4 of VCRM connector, observe test light and repeat power-to-cooling fan circuit wiggle test. If a short to ground is detected (test light gets brighter), isolate fault and repair as necessary. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If a short to ground is not detected, fault is intermittent and cannot be duplicated at this time. Testing is complete. Reconnect all components. NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 25) to step 30). No test procedures have been omitted.
18. 30) Code 582 KOEO Code 582 indicates an open or short to power in cooling fan circuit. Following are possible causes for this fault. Open or short to power in cooling fan circuit. Open cooling fan motor ground circuit. Open circuit in cooling fan. Faulty VCRM. If KOEO Code 587 is also present, repair fault causing KOEO Code 587 to set prior to continuing this test. Go to step 170). Ensure cooling fan was not turning during KOEO self-test. If fan was turning, feedback voltage could be sent to VCRM through power-to-cooling fan circuit, resulting in an invalid KOEO Code 582. Ensure engine is cooled down (cooling fan off). Ensure defroster and A/C are off. Turn ignition off. Check cooling fan. If cooling fan is on, go to step 35). If cooling fan is off, go to next step.
19. 31) Check Power To Cooling Fan Turn ignition off. Disconnect cooling fan connector. Start engine. Turn A/C on. Measure voltage between ground and power to cooling fan circuit (Light Blue wire) at cooling fan connector. If voltage is 6 volts or more, turn ignition off. Replace cooling fan. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If voltage is less than 6 volts, go to next step.
20. 32) Check Continuity Of Cooling Fan Circuit Turn ignition off. Ensure cooling fan is disconnected. Measure resistance between ground circuit (Black wire) at cooling fan motor connector and negative battery terminal. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Black wire between cooling fan motor connector and ground. Reconnect cooling fan connector. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
21. 33) Check Continuity Of Cooling Fan Circuit (Cont.) Turn ignition off. Ensure cooling fan is disconnected. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Measure resistance between Light Blue wire at cooling fan motor connector and terminals No. 2 and 3 of VCRM connector. If resistance is less than 5 ohms, replace VCRM. Reconnect all components. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If resistance is 5 ohms or more, repair open in power-to-cooling fan circuit (Light Blue wire). Reconnect all components. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 33) to step 35). No test procedures have been omitted.
22. 35) Check Power To Cooling Fan Circuit For Short To Power Turn ignition off. Disconnect cooling fan motor connector. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Turn ignition on. Measure voltage between Light Blue wire at cooling fan connector and negative battery terminal. If voltage is less than one volt, replace VCRM. Reconnect all components. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If voltage is more than one volt, repair short to power in Light Blue wire. Reconnect all components. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 35) to step 40). No test procedures have been omitted.
23. 40) Continuous Memory Code 578 Continuous Memory Code 578 indicates A/C Pressure (ACP) sensor VREF circuit is shorted to ground. This could be due to a hard fault or an intermittent condition. Following are possible causes for this fault. ACP sensor VREF circuit is shorted to ground. Faulty ACP sensor. Faulty VCRM. Clear continuous memory. Start engine. Wait 15 seconds. Turn ignition off. Perform Key On Engine Off (KOEO) SELF-TEST. If Code 578 is present (hard code), go to next step. If Code 578 is not present (intermittent), go to step 44).
24. 41) Check ACP Sensor Clear continuous memory. Turn ignition off. Disconnect ACP sensor connector. Start engine and wait 15 seconds. Turn ignition off. Perform Key On Engine Off (KOEO) SELF-TEST. If Code 578 is present, go to next step. If Code 578 is not present, replace ACP sensor. Clear continuous memory. Start engine and wait 15 seconds. Turn ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
25. 42) Check ACP VREF Circuit For Short To Ground Ensure ACP sensor is disconnected. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Measure resistance between ACP VREF circuit (Orange/Light Blue wire) at ACP sensor connector and negative battery terminal. If resistance is more than 10,000 ohms, replace VCRM. Reconnect all components. Clear continuous memory. Start engine and wait 15 seconds. Turn ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If resistance is 10,000 ohms or less, repair short to ground in ACP VREF circuit (Orange/Light Blue wire). NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 42) to step 44). No test procedures have been omitted.
26. 44) Check For Intermittent Short To Ground In ACP VREF Circuit Turn ignition off. Visually inspect ACP VREF circuit between terminal No. 20 (Orange/Light Blue wire) at VCRM connector and ACP sensor connector. Repair wiring as necessary. Disconnect and inspect ACP sensor connector. Clean or repair connector as necessary. Disconnect and inspect VCRM connector. Clean and repair connector as necessary. Connect test light between terminals No. 6 (Yellow wire) and No. 20 (Orange/Light Blue wire) at VCRM connector. Observe test light, and shake, wiggle and bend ACP VREF circuit between ACP sensor connector and VCRM connector. If a fault is detected, test light will turn on, indicating a short to ground. If a short to ground is detected, isolate fault and repair wiring as necessary. Reconnect all components. Start engine and wait 15 seconds. Turn ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If a short to ground is not detected, fault is intermittent and cannot be duplicated. Testing is complete. Reconnect all components. NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 44) to step 50). No test procedures have been omitted.
27. 50) Continuous Memory Code 579: Check ACP, VREF and ACP SIG RTN Circuits Continuous Memory Code 579 indicates A/C Pressure (ACP) sensor did not detect a sufficient change in A/C system pressure when A/C system was turned on. This could be due to a problem in ACP sensor circuit or A/C system, and can be a hard fault or an intermittent condition. Following are possible causes for this fault. Open or shorted ACP sensor circuit. Faulty ACP sensor. Faulty VCRM. Power to A/C clutch circuit open. Continuous Memory Code 586 may also be present. If Continuous Memory Code 586 is present, repair fault causing code prior to continuing this test. Go to step 80). If Code 586 is not present, turn ignition off. Disconnect ACP sensor. Turn ignition on. Measure voltage between ACP VREF terminal (Orange/Light Blue wire) and ACP SIG RTN terminal (Light Blue/Red wire) at ACP sensor connector. (Scheme 70) If voltage is more than 6 volts, go to step 62). If voltage is less than 4 volts, go to step 63). If voltage is 4-6 volts, go to next step. (Scheme 70): Identifying ACP Sensor Wiring Harness Connector Terminals
28. 51) Check If A/C Clutch Engages Turn ignition off. Reconnect ACP sensor. Start engine. Turn A/C on and wait 30 seconds. If A/C clutch engages, go to next step. If A/C clutch does not engage go to step 57).
29. 52) Clear And Attempt To Reset Code 579 Clear continuous memory. Start engine. Turn A/C on and wait until clutch engages. Turn A/C off and wait 5 seconds. Repeat turning A/C on and off 4 more times with each engagement lasting about 20 seconds. Turn A/C and engine off. Repeat Key On Engine Off (KOEO) self-test. If Code 579 is present, go to next step. If Code 579 is not present, ACP is now functioning. Either ACP is intermittent or marginal mechanical condition exists in A/C system, go to step 66).
30. 53) Check A/C System Pressure & Pressure Change Turn ignition off. Ensure ACP sensor is disconnected. Install A/C system manifold gauge set. With A/C off, start engine. Observe A/C high pressure gauge reading, and turn A/C on. After 10 seconds, note pressure reading. High pressure should increase. If A/C high pressure gauge reading changes by more than 20 psi within 10 seconds of A/C clutch engagement, turn A/C and ignition off and go to next step. If A/C high pressure gauge reading does not change by more than 20 psi within 10 seconds of turning A/C on, check A/C system for mechanical fault. Service A/C system as necessary. Clear continuous memory. Attempt to reset Code 579 (see step 52) for reset procedure only). Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
31. 54) Check ACP Sensor Output Turn ignition off. Ensure ACP sensor is disconnected. Install A/C system manifold gauge set. Connect jumper wires and DVOM between ACP sensor connector halves as shown. (Scheme 71) Start engine and observe voltage reading on DVOM. Turn A/C on and observe voltage reading for 10 seconds after clutch engages. NOTE: Listen to A/C clutch to ensure clutch does not disengage during 10 seconds of testing. If clutch disengages, retest. If ACP sensor voltage changes by more than.2 volt within 10 seconds of clutch engagement, sensor is operational. Remove jumper wires and go to next step. If ACP sensor voltage does not change by more than.2 volt within 10 seconds of turning A/C on, replace ACP sensor. Remove A/C system manifold gauge set. Remove jumper wires, and reconnect all components. Clear continuous memory. Attempt to reset Code 579 (see step 52) for reset procedure only). Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). (Scheme 71): Testing ACP Sensor
32. 55) Check ACP Circuit For Short To Ground Turn ignition off. Ensure ACP sensor is disconnected. Disconnect VCRM connector. Measure resistance between negative battery terminal and ACP circuit terminal (Dark Green/White wire) at ACP sensor wiring harness connector. Record resistance reading. Measure resistance between ACP circuit terminal (Dark Green/White) and ACP SIG RTN circuit (Light Blue/Red wire) at ACP sensor wiring harness connector. If each reading is more than 10,000 ohms, replace VCRM. Reconnect all components, clear continuous memory attempt to reset Code 579 (see step 52) for reset procedure only). Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If any reading is 10,000 ohms or less, ACP or ACP SIG RTN circuit is shorted to ground. Repair shorted circuit, reconnect all components and clear continuous memory. Attempt to reset Code 579 (see step 52) for reset procedure only). Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 55) to step 57). No test procedures have been omitted.
33. 57) Check Voltage To A/C Clutch Turn ignition off. Disconnect A/C cycling pressure switch. Connect a jumper wire between of A/C cycling pressure switch wiring harness connector terminals. Disconnect A/C clutch connector. Connect a test light between A/C clutch wiring harness connector terminals. Start engine. Turn A/C on and wait 10 seconds. If test light is off, go to next step. If test light is on, circuit is okay. Check A/C system for mechanical problems. Reconnect all components, clear continuous memory. Attempt to reset Code 579 (see step 52) for reset procedure only). Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
34. 58) Check Continuity Of ACP Circuit Turn ignition off. Ensure ACP sensor is disconnected. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Measure resistance between ACP signal terminal at ACP wiring harness connector and terminal No. 19 (Dark Green/White wire) at VCRM wiring harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in ACP circuit (Dark Green/White wire). Remove A/C system manifold gauge set. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
35. 59) Check ACP Circuit For Short To ACP VREF Turn ignition off. Ensure ACP sensor and VCRM are disconnected. Measure resistance between ACP signal terminal (Dark Green/White wire) and ACP VREF terminal (Orange/Light Blue wire) at ACP sensor wiring harness connector. If resistance is more than 10,000 ohms, go to next step. If resistance is 10,000 ohms or less, ACP signal circuit is shorted to ACP VREF circuit. Repair as necessary. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 20 seconds. Turn A/C and ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
36. 60) Check ACP Circuit For Short To Power Turn ignition off. Ensure ACP sensor and VCRM are disconnected. Turn ignition on. Measure voltage between ACP signal terminal (Dark Green/White wire) at ACP sensor wiring harness connector and negative battery terminal. If voltage is less than one volt, go to next step. If voltage is one volt or more, repair short to power in ACP circuit. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
37. 61) Check If Test Light Will Turn On With ACP Circuit Grounded Turn ignition off. Ensure ACP sensor is disconnected. Reconnect VCRM. Disconnect A/C cycling pressure switch. Connect a jumper wire between A/C cycling pressure switch wiring harness connector terminals. Disconnect A/C compressor clutch connector. Connect a test light between wiring harness side of A/C compressor clutch connector terminals. Connect a jumper wire between negative battery terminal and ACP signal circuit (Dark Green/White wire) at ACP sensor wiring harness connector. (Scheme 70) Start engine. Turn A/C on and wait 10 seconds. Observe test light. If test light is on, replace ACP sensor. Turn A/C off. Reconnect all components. Clear continuous memory. Start engine and turn A/C on for 20 seconds then turn ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If test light is off, replace VCRM. Reconnect all components. Clear continuous memory. Start engine and turn A/C on for 20 seconds then turn ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
38. 62) Check For Short To Power In ACP VREF Circuit Turn ignition off. Ensure ACP sensor is disconnected. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Turn ignition on. Measure voltage between negative battery terminal and ACP VREF terminal (Orange/Light Blue wire) at ACP sensor wiring harness connector. If voltage is less than one volt, replace VCRM. Reconnect all components. Clear continuous memory. Attempt to reset Code 579 (see step 52) for procedure only). Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If voltage is one volt or more, repair short to power in ACP VREF circuit (Orange/Light Blue wire). Reconnect all components. Clear continuous memory. Attempt to reset Code 579 (see step 52) for procedure only). Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
39. 63) Check Continuity Of ACP SIG RTN & VREF Circuits Turn ignition off. Ensure ACP sensor is disconnected. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Measure resistance between ACP SIG RTN terminal (Light Blue/Red wire) at ACP sensor wiring harness connector and terminal No. 12 (Light Blue/Red wire) at VCRM wiring harness connector. Record resistance reading. Measure resistance between ACP VREF terminal (Orange/Light Blue wire) at ACP sensor wiring harness connector and terminal No. 20 (Orange/Light Blue wire) at VCRM wiring harness connector. If both readings are less than 5 ohms, go to next step. If any reading is 5 ohms or more, repair open in ACP VREF circuit (Orange/Light Blue wire) or ACP SIG RTN circuit (Light Blue/Red wire). Reconnect all components. Clear continuous memory. Start engine. Attempt to reset Code 579 (see step 52) for procedure only). Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
40. 64) Check ACP SIG RTN Circuit For Short To VREF Turn ignition off. Ensure ACP sensor and VCRM connectors are disconnected. Measure resistance between ACP SIG RTN terminal (Light Blue/Red wire) and ACP VREF terminal (Orange/Light Blue wire) at ACP sensor wiring harness connector. If resistance is more than 10,000 ohms, go to next step. If resistance is 10,000 ohms or less, ACP SIG RTN circuit is shorted to ACP VREF circuit. Repair wiring as necessary. Reconnect all components. Clear continuous memory. Attempt to reset Code 579 (see step 52) for procedure only). Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
41. 65) Check For Short To Power In ACP SIG RTN Circuit Turn ignition off. Ensure ACP sensor and VCRM connectors are disconnected. Turn ignition on. Measure voltage between negative battery terminal and ACP SIG RTN terminal (Light Blue/Red wire) at ACP sensor wiring harness connector. If voltage is less than one volt, replace VCRM. Reconnect all components. Clear continuous memory. Attempt to reset Code 579 (see step 52) for procedure only). Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If voltage is one volt or more, repair short to power in ACP SIG RTN circuit (Light Blue/Red wire). Reconnect all components. Clear continuous memory. Attempt to reset Code 579 (see step 52) for procedure only). Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
42. 66) Check A/C Cooling Performance Check A/C system performance. If A/C system cools properly, go to step 67). If A/C system does not cool properly, Check mechanical condition of A/C system. If mechanical condition is okay, go to next step.
43. 67) Check For Intermittent Open In ACP VREF & ACP SIG RTN Circuits Turn A/C and ignition off. Disconnect and inspect ACP sensor connector. Clean or repair connector as necessary. Turn ignition on. Connect test light between ACP VREF terminal (Orange/Light Blue wire) and ACP SIG RTN terminal (Light Blue/Red wire) at ACP sensor wiring harness connector. Test light should turn on. If test light does not glow sufficiently, a DVOM may be used instead of test light to monitor 5-volt reference signal. Observe test light/DVOM, and shake, wiggle and bend ACP VREF and ACP SIG RTN circuits between ACP sensor connector and VCRM connector. If a fault is detected, test light will turn off or DVOM voltage will drop, indicating open circuit. If open circuit is detected, isolate fault and repair wiring as necessary. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 20 seconds. Turn A/C and ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If open circuit is not detected, go to next step.
44. 68) Check ACP Signal Circuit For Intermittent Short Turn ignition off. Ensure ACP sensor is disconnected. Connect test light or DVOM between ACP VREF terminal (Orange/Light Blue wire) and ACP signal terminal (Dark Green/White wire) at ACP sensor connector. Test light should be off or DVOM reading should be zero volts. Observe test light/DVOM, and shake, wiggle and bend ACP signal circuit (Dark Green/White wire) between ACP sensor connector and VCRM connector. Lightly tap on VCRM to simulate road shock. If a fault is detected, test light will turn on or DVOM reading will show 5 volts, indicating a short to ground. If a short to ground is detected, isolate fault and repair wiring as necessary. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 20 seconds. Turn A/C and ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If a short to ground is not detected, remove test light/DVOM. Reconnect test light/DVOM between ACP SIG RTN terminal (Light Blue/Red wire) and ACP signal terminal (Dark Green/White wire) at ACP sensor wiring harness connector. Observe test light/DVOM, and repeat wiggle test of ACP signal circuit. If a fault is detected, test light will turn on or DVOM reading will show 5 volts, indicating a short to power. If a short to power is detected, isolate fault and repair wiring as necessary. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 20 seconds. Turn A/C and ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If short to power is not detected, go to next step.
45. 69) Check ACP Signal Circuit For Intermittent Open Turn ignition off. Ensure ACP sensor is disconnected. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Using a DVOM, measure resistance of Dark Green/White wire between terminal No. 19 at VCRM wiring harness connector and ACP signal terminal at ACP sensor wiring harness connector. (Scheme 70) If resistance is 5 ohms or more, isolate fault and repair wiring as necessary. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 20 seconds. Turn A/C and ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If resistance is less than 5 ohms, observe DVOM, and shake, wiggle and bend ACP signal circuit (Dark Green/White wire) between ACP sensor wiring harness connector and VCRM wiring harness connector. If a fault is detected, DVOM reading will show 5 ohms or more, indicating an open circuit. If an open circuit is detected, isolate fault and repair wiring as necessary. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 20 seconds. Turn A/C and ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If an open circuit is not detected, fault is intermittent and cannot be duplicated at this time. Reconnect all components.
46. 70) Continuous Memory Code 585 Continuous Memory Code 585 indicates that power to A/C clutch exceeded normal current draw when A/C was turned on. This could be due to a hard fault or an intermittent condition. Following are possible causes for this fault. Short to ground in power to A/C clutch circuit. Faulty A/C clutch. Faulty VCRM. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Perform Key On Engine Off (KOEO) SELF-TEST. If Code 585 is present (hard code), go to next step. If Code 585 (intermittent) is not present, go to step 74).
47. 71) Check A/C Clutch Clear continuous memory. Disconnect A/C clutch connector. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat Key On Engine Off (KOEO) self-test. Ignore Code 586 if set. If Code 585 is present, go to next step. If Code 585 is not present, check for short to ground in A/C clutch wiring circuit. Repair wiring as necessary. If wiring is okay, replace A/C clutch. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
48. 72) Check For Short To Ground In A/C Clutch Circuit Turn ignition off. Ensure A/C clutch is disconnected. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Measure resistance between Purple wire at A/C clutch connector and negative battery terminal. If resistance is more than 10,000 ohms, replace VCRM. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If resistance is 10,000 ohms or less, repair short to ground in Purple wire. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 72) to step 74). No test procedures have been omitted.
49. 74) Check For Intermittent Short To Ground In Power-To-A/C Clutch Circuit Turn ignition off. Visually inspect Purple wire between A/C clutch and VCRM. Repair wiring as necessary. Start engine and turn A/C on. Shake, wiggle and bend Purple wire between A/C clutch connector and VCRM. A short to ground will be indicated by A/C clutch disengaging for other than normal A/C cycling pressure switch operation. If a short to ground is not detected, go to next step. If a short to ground is detected, isolate fault and repair as necessary. Clear continuous memory (Code 585 should have been set). Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
50. 75) Check A/C Clutch Circuit For Intermittent Short To Ground Turn ignition off. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Disconnect and inspect A/C clutch connector. Clean or repair connector as necessary. Connect a test light between terminals No. 4 (Yellow wire) and No. 14 (Purple wire) at VCRM connector. Observe test light, and shake, wiggle and bend Purple wire between A/C clutch connector and VCRM connector. If a fault is detected, test light will turn on, indicating a short to ground. If a short to ground is detected, isolate fault and repair wiring as necessary. Reconnect all components. Start engine and wait 15 seconds. Turn ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If a short to ground is not detected, fault is intermittent and cannot be duplicated at this time. Testing is complete. Reconnect all components. NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 75) to step 80). No test procedures have been omitted.
51. 80) Continuous Memory Code 586 Continuous Memory Code 586 indicates an open or short to power in A/C clutch circuit. This could be due to a hard fault or an intermittent condition. Following are possible causes for this fault. Open or short to power in A/C clutch wiring harness. Open A/C clutch ground (VCRM terminal No. 13). Open VCRM A/C ground (VCRM terminal No. 15 to weld nut on left side of radiator support). A/C clutch open circuit. Damaged VCRM. Clear continuous memory. Turn A/C and defroster off. Start engine and wait 15 seconds. Turn ignition off. Perform Key On Engine Off (KOEO) SELF-TEST. If Code 586 is present (hard code), go to next step. If Code 586 is not present, fault is intermittent. Go to step 85).
52. 81) Check Short To Power In A/C Clutch Circuit Turn ignition off. Disconnect A/C clutch connector. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Turn ignition on. Start engine and wait 15 seconds. Turn ignition off. Measure voltage at Purple wire between negative battery terminal and A/C clutch wiring harness connector. If voltage is less than one volt, go to next step. If voltage is one volt or more, repair short to power in Purple wire. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
53. 82) Check Continuity Of A/C Clutch & VCRM A/C Ground Circuits Turn ignition off. Ensure A/C clutch and VCRM are disconnected. Measure resistance of Purple wire between terminal No. 14 at VCRM wiring harness connector and A/C clutch wiring harness connector. Record resistance reading. Measure resistance between terminal No. 13 (Gray/White wire) at VCRM wiring harness connector and A/C clutch ground circuit (Black wire) at A/C clutch wiring harness connector. If both resistance readings are less than 5 ohms, go to next step. If any resistance reading is 5 ohms or more, repair open in circuit(s). Reconnect all components. Clear continuous memory. With A/C and defroster off, start engine. Wait 15 seconds. Turn ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
54. 83) Check A/C Clutch Continuity Turn ignition off. Ensure A/C clutch and VCRM are disconnected. Measure resistance between A/C clutch terminals. If resistance is less than 10 ohms, replace VCRM. Reconnect all components. Clear continuous memory. With A/C and defroster off, start engine. Wait 15 seconds. Turn ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If resistance is 10 ohms or more, replace A/C clutch. Reconnect all components. Clear continuous memory. With A/C and defroster off, start engine. Wait 15 seconds. Turn ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 83) to step 85). No test procedures have been omitted.
55. 85) Check For Intermittent Open In A/C Clutch & VCRM A/C Ground Circuits Turn ignition off. Visually inspect power-to-A/C clutch circuit (terminal No. 14) and A/C clutch ground circuit (terminal No. 13) between VCRM and A/C clutch. Also, check VCRM ground circuit (terminal No. 15) between VCRM connector and ground point at left side of radiator support. Repair wiring as necessary. Start engine. Turn A/C on. Shake, wiggle and bend power-to-A/C clutch circuit (Purple wire), A/C clutch ground circuit (Gray/White wire) and VCRM A/C ground (Black wire) circuit. An open will be indicated by A/C clutch disengaging for other than normal cycling pressure switch operation. If an open circuit is detected, isolate fault and repair as necessary. Turn A/C and ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If an open is not detected, go to next step.
56. 86) Check For Intermittent Short To Power In A/C Clutch Circuit Ensure A/C is off. Turn ignition on. Shake, wiggle and bend power-to-A/C clutch circuit (Purple wire) between VCRM and A/C clutch. A short to power will be indicated by A/C clutch engaging. If a short to power is detected, isolate fault and repair as necessary. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If a short to power is not detected, go to next step.
57. 87) Check For Intermittent Open In A/C Clutch & VCRM A/C Ground Circuits Turn ignition off. Disconnect and inspect A/C clutch connector. Clean or repair connector as necessary. Connect test light between power-to-A/C clutch terminal (Purple wire) and A/C clutch ground terminal (Gray/White wire) at A/C clutch wiring harness connector. Start engine. Turn A/C on. Observe test light, and shake, wiggle and bend power-to-A/C clutch circuit (Purple wire), A/C clutch ground circuit (Gray/White wire) and VCRM A/C ground (Black wire) circuit. Test light will turn off when a fault is detected, indicating an open circuit. If an open circuit is detected, isolate fault and repair as necessary. Reconnect all components. Turn A/C and ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If an open circuit is not detected, disconnect and inspect VCRM connector. Clean or repair connector as necessary. If connector is okay, fault is intermittent and cannot be duplicated at this time. Testing is complete. Reconnect all components. NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 87) to step 90). No test procedures have been omitted. NOTE: Before proceeding with "No A/C" diagnostic procedures, check related fuses in fuse panel.
58. 90) No A/C (With Code 111): Check Power At A/C Clutch Turn ignition off. Disconnect A/C clutch connector. Connect test light between power-to-A/C clutch circuit (Purple wire) and A/C clutch ground circuit (Gray/White wire) at A/C clutch wiring harness connector. Start engine. Turn A/C on and wait 10 seconds. Observe test light. If test light glows, EEC-IV system is okay. Reconnect A/C clutch connector. Check A/C system for mechanical problems. Repair A/C system as necessary. If test light is off, go to next step.
59. 91) Check If PCM Is Receiving & Recognizing A/C Cycling Pressure (ACCS) Input Turn ignition off. Remove test light, and reconnect A/C clutch connector. Perform Key On Engine Off (KOEO) SELF-TEST. If KOEO Code 539 is present, PCM is receiving and recognizing ACCS input. Go to next step. If KOEO Code 539 is not present, PCM is not receiving or recognizing ACCS input. Go to step 96).
60. 92) Check A/C Demand Signal Power At VCRM Turn ignition off. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Turn A/C and ignition on. Measure voltage between terminal No. 9 (Black/Yellow wire) at VCRM wiring harness connector and negative battery terminal. If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, repair open in A/C demand signal circuit (Black/Yellow wire) between VCRM splice and PCM. Reconnect all components. Recheck system operation.
61. 93) Check For Short To Ground In Wide Open Throttle A/C Cut -Off (WAC) Circuit Turn ignition off. Ensure VCRM is disconnected. Disconnect PCM connector. Clean or repair connector as necessary. Measure resistance between terminal No. 11 (Pink/Yellow wire) at VCRM wiring harness connector and negative battery terminal. If resistance is more than 10,000 ohms, go to next step. If resistance is 10,000 ohms or less, repair short to ground in WAC circuit. Reconnect all components. Recheck system operation.
62. 94) Verify WAC Circuit Is Not Shorted To Ground In PCM Turn ignition off. Disconnect PCM connector. Reconnect VCRM connector. Disconnect A/C clutch connector. Connect test light between power-to-A/C clutch circuit (Purple wire) and A/C clutch ground circuit (Gray/White wire) at A/C clutch wiring harness connector. Turn A/C and ignition on. If test light is on, replace PCM. Reconnect all components. Recheck system operation. If test light is off, replace VCRM. Reconnect all components. Recheck system operation. NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 94) to step 96). No test procedures have been omitted.
63. 96) Check For A/C Demand Signal Power At A/C Cycling Pressure Switch Turn ignition off. Disconnect A/C cycling pressure switch. Turn A/C and ignition on. Measure voltage between negative battery terminal and A/C cycling pressure switch wiring harness connector (circuit from Electronic Automatic Temperature Control (EATC) module). If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, ensure voltage is available to EATC module, EATC module is functioning properly. If voltage to EATC module is okay, repair open circuit between EATC module and A/C cycling pressure switch. Reconnect all components. Recheck system operation.
64. 97) Check A/C Cycling Pressure Switch Continuity Turn ignition off. Disconnect A/C cycling pressure switch. Check continuity between A/C cycling switch terminals. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, check A/C system pressure and A/C cycling pressure switch operation.
65. 98) Check Continuity Between A/C Cycling Pressure Switch & PCM Turn ignition off. Ensure A/C cycling pressure switch is disconnected. Install breakout box. Leave PCM disconnected. Measure resistance between test pin No. 10 at breakout box and circuit to PCM/VCRM at A/C cycling pressure switch wiring harness connector. If resistance is less than 5 ohms, replace PCM. Remove breakout box, and reconnect all components. Recheck system operation. If resistance is 5 ohms or more, repair open in circuit between A/C cycling pressure switch and PCM. Remove breakout box, and reconnect all components. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 98) to step 100). No test procedures have been omitted.
66. 100) Lack Of Power With A/C On; Verify Wide Open Throttle A/C Cut-Off (WAC) Is Able To Turn Off A/C Clutch Start engine. Turn A/C on. Perform a brief Wide Open Throttle (WOT) and return to idle.A/C clutch should disengage during WOT, then a few seconds after returning to idle, A/C clutch should re-engage (click noise should be heard when clutch re-engages). Repeat test if necessary to verify results. If clicking noise cannot be heard, disconnect A/C clutch. Connect test light between power-to-A/C clutch circuit and ground circuit at wiring harness side of A/C clutch connector. Perform brief WOT. Test light should turn off during WOT, then turn on a few seconds after engine speed returns to idle. If A/C clutch or test light functions as specified, WAC circuit is okay. Test is complete. If A/C clutch or test light does not function as specified, go to next step.
67. 101) Check WAC Circuit Wiring Harness Continuity Turn ignition off. Disconnect and inspect PCM connector. Clean or repair connector as necessary. Install breakout box. Leave PCM disconnected. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Measure resistance between test pin No. 54 at breakout box and terminal No. 11 (Pink/Yellow wire) at VCRM wiring harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in WAC circuit. Remove breakout box, and reconnect all components. Recheck system operation.
68. 102) Check WAC Circuit For Short To Power Turn ignition off. Ensure breakout box is still connected. Ensure VCRM and PCM are disconnected. Turn ignition on. Measure voltage between test pins No. 40 and 54 at breakout box. If voltage is less than one volt, go to next step. If voltage is one volt or more, repair short to power in WAC circuit. Remove breakout box, and reconnect all components. Recheck system operation.
69. 103) Check VCRM WAC Circuitry Turn ignition off. Ensure breakout box is still connected and PCM is disconnected. Reconnect VCRM connector. Turn ignition and A/C on. Connect a jumper wire to test pin No. 54 at breakout box. Listen to A/C clutch while briefly touching other end of jumper wire to test pin No. 40 at breakout box. Repeat procedure as necessary. If A/C clutch disengages and re-engages as jumper wire is connected and disconnected, replace PCM. Remove breakout box, and reconnect all components. Recheck system operation. If A/C clutch does not disengage and re-engage as jumper wire is connected and disconnected, replace VCRM. Remove breakout box, and reconnect all components. Recheck system operation. NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 103) to step 110). No test procedures have been omitted.
70. 110) Code 556 KOEO Code 556 indicates a fuel pump primary circuit failure. Possible causes for this fault are an open or short to fuel pump circuit, damaged VCRM or damaged PCM. Check if engine will start. If engine starts, go to step 115). If engine does not start, go to next step.
71. 111) Check Fuel Pump Circuit Continuity Turn ignition off. Disconnect and inspect PCM and VCRM connectors. Clean or repair connectors as necessary. Install breakout box. Leave PCM and VCRM disconnected. Measure resistance between test pin No. 22 at breakout box and terminal No. 18 (Light Blue/Orange wire) at VCRM wiring harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in fuel pump circuit. Remove breakout box, and reconnect all components. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
72. 112) Check For Short To Power In Fuel Pump Circuit Turn ignition off. Ensure breakout box is still connected and PCM is disconnected. Disconnect VCRM connector. Turn ignition on. Measure voltage between test pins No. 22 and 40 at breakout box. If voltage is less than one volt, go to next step. If voltage is one volt or more, repair short to power in fuel pump circuit. Remove breakout box, and reconnect all components. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
73. 113) Check VCRM Fuel Pump Circuit Turn ignition off. Ensure break-out box is still connected and PCM is disconnected. Reconnect VCRM connector. Connect jumper wire between test pins No. 22 and 40 at breakout box. Listen to fuel pump, and turn ignition on. If fuel pump runs, turn ignition off. Remove jumper wire. Replace PCM. Remove breakout box, and reconnect all components. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If fuel pump does not run, turn ignition off. Remove jumper wire. Replace VCRM. Remove breakout box, and reconnect all components. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 113) to step 115). No test procedures have been omitted.
74. 115) Check For Short To Ground In PCM Turn ignition off. Disconnect and inspect PCM connector. Clean or repair connector as necessary. Turn ignition on. Listen to fuel pump. If fuel pump runs, turn ignition off and go to next step. If fuel pump does not run, turn ignition off. Replace PCM. Reconnect all components. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
75. 116) Check For Short To Ground In Fuel Pump Circuit Turn ignition off. Install breakout box. Leave PCM disconnected. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Measure resistance between test pins No. 22 and 40 at breakout box. If resistance is more than 10,000 ohms, replace VCRM. Remove breakout box, and reconnect all components. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If resistance is 10,000 ohms or less, repair short to ground in fuel pump circuit. Remove breakout box, and reconnect all components. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 116) to step 120). No test procedures have been omitted.
76. 120) Code 542 KOEO Code 542 indicates that one of the following has occurred. No-Start Inertia Fuel Shutoff (IFS) switch not reset or open. Open in power-to-fuel pump circuit between fuel pump monitor (FPM) terminal at PCM (terminal No. 8) and fuel pump. Poor fuel pump ground. Open circuit in fuel pump. Engine Starts Short to power in fuel pump/FPM circuit. High speed fuel pump (HFP) relay contacts stuck closed. Short to ground in HFP circuit (VCRM terminal No. 10). Open FPM circuit between PCM and power-to-fuel pump splice. Short to power in left heated oxygen sensor (HO2S). Damaged VCRM. Damaged PCM. Check if engine will start and idle for one minute. If engine starts and idles for one minute, go to next step. If engine does not start or starts but does not idle for one minute, go to step 130).
77. 121) Verify Fuel Pump Is Off Turn ignition on, and wait 5 seconds. Listen for motor noise from fuel pump. If fuel pump is off, go to step 126). If fuel pump is on, go to next step.
78. 122) Check VCRM Turn ignition off. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Turn ignition on. Listen for fuel pump noise. If fuel pump is off, turn ignition off. Replace VCRM. Reconnect all components. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If fuel pump is on, turn ignition off and go to next step.
79. 123) Check HFP Relay & Circuits Turn ignition off. Ensure VCRM is disconnected. Disconnect HFP relay. Relay is located in engine compartment fuse block. Turn ignition on. Listen to fuel pump. If fuel pump is off, go to next step. If fuel pump is on, turn ignition off. Repair short to power in power-to-fuel pump/FPM circuit. Reconnect all components. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
80. 124) Check For Short To Ground In HFP Circuit Turn ignition off. Ensure VCRM and HFP relay are disconnected. Measure resistance between negative battery terminal and terminal No. 10 (Brown/White wire) at VCRM wiring harness connector. If resistance is more than 10,000 ohms, replace HFP relay. Reconnect all components. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If resistance is 10,000 ohms or less, repair short to ground in HFP circuit. Reconnect all components. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 124) to step 126). No test procedures have been omitted.
81. 126) Check FPM Circuit Continuity Turn ignition off. Disconnect and inspect PCM connector. Clean or repair connector as necessary. Install breakout box. Leave PCM disconnected. Disconnect HFP relay. Measure resistance between test pin No. 8 at breakout box and power-to-fuel pump terminal (Pink/Black wire) at HFP relay connector. (Scheme 72) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in FPM circuit between PCM and splice to power-to-fuel pump circuit. Remove breakout box, and reconnect all components. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). (Scheme 72): High Speed Fuel Pump (HFP) Relay Vehicle Wiring Harness Connector Terminals NOTE: Due to internal circuitry of PCM a left HO2S signal short to power may produce a Code 524, 542 or 543.
82. 127) Check For Short To Power In Left HO2S Turn ignition off. Disconnect left HO2S. Measure resistance between HO2S SIGNAL terminal and KEY POWER terminal at HO2S connector. (Scheme 73) If resistance is more than 10,000 ohms, to next step. If resistance is 10,000 ohms or less, replace HO2S. Reconnect all components. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). (Scheme 73): Identifying Heater Oxygen Sensor (HO2S) Terminals
83. 128) Check For Short To Power In Left HO2S Circuit Turn ignition off. Ensure left HO2S is disconnected. Disconnect and inspect PCM connector. Clean or repair connector as necessary. Turn ignition on. Measure voltage between negative battery terminal and HO2S SIGNAL terminal (Red/Black wire) at HO2S wiring harness connector. (Scheme 73) If voltage is less than 2 volts, replace PCM. Reconnect all components. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If voltage is 2 volts or more, repair short to power in left HO2S circuit. NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 128) to step 130). No test procedures have been omitted.
84. 130) Check Inertia Fuel Shutoff (IFS) Switch Turn ignition off. Disconnect IFS switch. IFS switch is located in left front of trunk. Ensure IFS switch button is in the down (set) position. Measure resistance between IFS switch terminals. If resistance is less than 5 ohms, reconnect IFS switch. Check for open in power-to-fuel pump circuit, open in fuel pump or poor fuel pump ground. Repair wiring as necessary. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If resistance is 5 ohms or more, attempt to reset IFS switch or replace IFS switch. Reconnect all components. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 130) to step 135). No test procedures have been omitted.
85. 135) Code 524, 543 & Continuous Memory Code 583 KOEO Code 524 or 543 indicates that when PCM commanded fuel pump on, voltage was not detected on Fuel Pump Monitor (FPM) circuit (PCM terminal No. 8). Code 524 refers to low speed output (VCRM terminal No. 24; Pink/Black wire). Code 543 refers to high speed output. It is not possible to distinguish between circuits due to vehicle wiring and fuel pump operating strategy. Continuous Memory Code 583 indicates that when fuel pump was activated, power-to-fuel pump exceeded normal current draw. This could be due to a hard fault or an intermittent condition. Following are possible causes for these faults. Without Continuous Memory Code 583 Open in power-to-fuel pump circuit between VCRM and FPM splice. Open in B (+) supply to VCRM (terminals No. 4 and 5). Short to power in left HO2S. With Continuous Memory Code 583 Short to ground in power-to-fuel pump/FPM circuit. If Continuous Memory Code 583 is present, go to next step. If Continuous Memory Code 583 is not present, go to step 144).
86. 136) Attempt To Re-Generate Continuous Memory Code 583 Turn ignition off. Clear continuous memory. See «CLEARING CODES»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__clearing-codes) under SELF-DIAGNOSTIC SYSTEM. Start engine. If engine will not start, crank engine for 5 seconds. Repeat «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test). If Continuous Memory Code 583 is present, code is a hard fault. Go to step 139). If Continuous Memory Code 583 is not present, code is intermittent. Go to next step.
87. 137) Was KOEO Code 524 Or 543 Present In Step 136) If KOEO Code 524 and/or 543 was present in step 136), an over-current condition (short to ground) was present sometime during last 80 warm-up cycles. Go to step 144). If KOEO Code 524 and/or 543 was not present in step 136), go to step 147). NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 137) to step 139). No test procedures have been omitted.
88. 139) Attempt To Isolate Short To Ground Turn ignition off. Clear continuous memory. Disconnect Inertia Fuel Shutoff (IFS) switch. IFS switch is located in left front of trunk. Crank engine for 5 seconds. Repeat «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test). If Continuous Memory Code 583 is present (disregard other codes), go to step 140). If Continuous Memory Code 583 is not present, check for short to ground in power-to-fuel pump circuit or fuel pump. Repair wiring or replace fuel pump as necessary. After repair is complete, repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
89. 140) Check For Short To Ground In Power-To-Fuel Pump/FPM Circuit Turn ignition off. Ensure IFS switch is disconnected. Disconnect and inspect PCM and VCRM connectors. Clean or repair connectors as necessary. Install breakout box. Leave PCM and VCRM disconnected. Measure resistance between test pins No. 8 and 40 at breakout box. If resistance is more than 10,000 ohms, go to next step. If resistance is 10,000 ohms or less, repair short to ground in power-to-fuel pump/FPM circuit. Remove breakout box, and reconnect all components. Clear continuous memory. Start engine and wait 5 seconds. Turn ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
90. 141) Check VCRM Turn ignition off. Ensure IFS switch is disconnected. Install breakout box. Leave PCM disconnected. Reconnect VCRM connector. Connect a jumper wire between test pins No. 22 and 40 at breakout box. Turn ignition on. Measure voltage between test pins No. 8 and 60 at breakout box. If voltage is more than 8.5 volts, replace PCM. Remove breakout box, and reconnect all components. Clear continuous memory. Start engine and wait 5 seconds. Turn ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If voltage is 8.5 volts or less, replace VCRM. Remove breakout box, and reconnect all components. Clear continuous memory. Start engine and wait 5 seconds. Turn ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 141) to step 144). No test procedures have been omitted.
91. 144) Check If Engine Starts With High Speed Fuel Pump (HFP) Relay Disconnected Turn ignition off. Disconnect HFP relay. Relay is located in engine compartment fuse block. Attempt to start engine. If engine does not start or starts but runs for less than one minute, go to next step. If engine starts and runs for one minute, reconnect HFP relay. Go to step 127).
92. 145) Check for B (+) To VCRM Turn ignition off. Ensure HFP relay is disconnected. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Connect negative lead of DVOM to negative battery terminal. Using positive lead of DVOM, measure voltage at terminals No. 4 (Yellow wire) and No. 5 (Yellow wire) at VCRM connector. If both voltage readings are more than 10.5 volts, go to next step. If any reading is 10.5 volts or less, repair open in B (+) supply to VCRM. Ensure all related fuses are okay. Reconnect all components. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
93. 146) Check Power-To-Fuel Pump Circuit Continuity Turn ignition off. Disconnect HFP relay and VCRM. Measure resistance between terminal No. 24 (Pink/Black wire) at VCRM wiring harness connector and power-to-fuel pump terminal at HFP relay. (Scheme 72) If resistance is less than 10 ohms, replace VCRM. Reconnect all components. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If resistance is 10 ohms or more, repair open in power-to-fuel pump circuit between VCRM and Fuel Pump Monitor (FPM) splice. Reconnect all components. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
94. 147) Check For Intermittent Short To Ground In Power-To-Fuel Pump Circuit Turn ignition off. Visually inspect power-to-fuel pump circuit between VCRM and fuel pump. Also, inspect Fuel Pump Monitor (FPM) circuit to PCM and power-to-fuel pump circuit at High Speed Fuel Pump (HFP) relay. Repair wiring as necessary. Install a fuel gauge or listen to fuel pump to check if fuel pump quits while performing wiggle test. Start engine. Shake, wiggle and bend Pink/Black wire (power-to-fuel pump circuit) between VCRM, fuel pump, PCM and HFP relay. To simulate road shock, lightly tap on Inertia Fuel Shutoff (IFS) switch, fuel pump, HFP relay, VCRM and fuel pump. If fuel pump stops, fuel pressure drops or engine stalls or stumbles, a short to ground in power-to-fuel pump circuit has been detected. Isolate fault and repair as necessary. Clear continuous memory (Code 583 should have been set). Start engine and wait 5 seconds. Turn ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If no fault is detected, go to next step.
95. 148) Again, Check For Intermittent Short To Ground In Power -To-Fuel Pump Turn ignition off. Disconnect PCM, VCRM and fuel pump. Inspect connectors. Clean or repair connectors as necessary. Install breakout box. Leave PCM, VCRM and fuel pump disconnected. Connect a test light between test pins No. 1 (KAPWR) and No. 8 (FPM) at breakout box. Observe test light, and shake, wiggle and bend Pink/Black wire (power-to-fuel pump circuit) between VCRM, fuel pump, PCM and HFP relay. To simulate road shock, lightly tap on Inertia Fuel Shutoff (IFS) switch, fuel pump, HFP relay and VCRM. If a fault is detected, test light will turn on, indicating a short to ground. If a short to ground is detected, isolate fault and repair wiring as necessary. Start engine and wait 5 seconds. Turn ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If a short to ground is not detected, fault is intermittent and cannot be duplicated at this time. Testing is complete. Reconnect all components. For further diagnosis, see the «TESTS W/O CODES»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wo-codes) article. NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 148) to step 150). No test procedures have been omitted.
96. 150) Continuous Memory Code 524, 543 Or 556 Continuous Memory Code 524 or 543 indicates that when PCM commanded fuel pump on, voltage was not detected at power-to-fuel pump circuit. Code 524 refers to low speed output (VCRM terminal No. 24; Pink/Black wire). Code 543 refers to high speed output. It is not possible to distinguish between circuits due to vehicle wiring and fuel pump operating strategy. Following are possible causes for these faults. Open in power-to-fuel pump circuit between VCRM and FPM splice. Open in B (+) supply to VCRM (terminals No. 4 and 5). Left HO2S short to power. Continuous Memory Code 556 indicates that sometime during vehicle operation, fuel pump primary circuit failure occurred. Possible cause for this fault is an open or short in fuel pump circuit (PCM terminal No. 22). If Continuous Memory Code 583 is also present, go to step 136). If Continuous Memory Code 583 is not present, go to next step.
97. 151) Check Power-To-Fuel Pump & Fuel Pump Circuits Start engine. Disconnect High Speed Fuel Pump (HFP) relay. Relay is located in engine compartment fuse block. Connect a test light between ground and power-to-fuel pump terminal at HFP relay vehicle wiring harness connector. (Scheme 72) If a fault is detected, test light will go out, indicating an open FP circuit. Also, listen for engine stall/stumble or fuel pump turning off. Observe test light and perform the following: For Code 524 or 543, shake, wiggle and bend Pink/Black wire (power-to-fuel pump circuit) between terminal No. 24 at VCRM and Fuel Pump Monitor (FPM) splice. Also shake, wiggle and bend Yellow wire (B (+) circuit) between terminals No. 4 and 5 at VCRM. For Code 556, shake, wiggle and bend Light Blue/Orange wire (fuel pump circuit) between terminals No. 22 at PCM and No. 18 at VCRM. If a short to ground is detected, isolate fault and repair wiring as necessary. Clear continuous memory. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If Code 556 is present and a short to ground is not detected, go to next step. If Code 556 is not present and a short to ground is not detected, go to step 158).
98. 152) Check For Intermittent Short To Ground In Fuel Pump Circuit Turn ignition off. Disconnect and inspect PCM and VCRM connectors. Clean or repair connectors as necessary. Connect ohmmeter between terminals No. 18 (Light Blue/Orange wire) and No. 1 (Black wire) at VCRM connector. Observe ohmmeter, and shake, wiggle and bend Light Blue/Orange wire (fuel pump circuit) between VCRM and PCM connectors. Also, check fuel pump circuit to Data Link Connector (DLC). If a fault is detected, ohmmeter will show continuity, indicating a short to ground. If continuity exists, isolate fault and repair wiring as necessary. Clear continuous memory. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If no continuity exists, fault is intermittent and cannot be duplicated at this time. Testing is complete. Reconnect all components. For further diagnosis, see the «TESTS W/O CODES»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wo-codes) article. NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 152) to step 155). No test procedures have been omitted.
99. 155) Continuous Memory Code 542 Continuous Memory Code 542 indicates that one of the following conditions has occurred. Fuel pump circuit activated when PCM expected circuit to be off. Open in fuel pump monitor (FPM) circuit, power to fuel pump, fuel pump or fuel pump ground circuit. Short to power in FPM or power-to-fuel pump circuits. VCRM output driver or High Speed Fuel Pump (HFP) relay contacts stuck closed. Short to ground in HFP circuit. Short to power in left HO2S signal circuit. Engine stall due to excessive load. Start engine. Check for engine stall/stumble while performing the following (if possible, listen for fuel pump turning off). Shake, wiggle and bend Pink/Black wire (power-to-fuel pump circuit) between fuel pump and FPM splice. To simulate road shock, lightly tap on fuel pump, Inertia Fuel Shutoff (IFS) switch and VCRM. If engine stalls or stumbles, isolate fault and repair wiring as necessary. Clear continuous memory. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If engine does not stall or stumble, go to next step.
100. 156) Check For Intermittent Open Or Short In FPM, Power-To -Fuel Pump & Fuel Pump Ground Circuits Turn ignition off. Disconnect and inspect PCM connector. Clean or repair connector as necessary. Install breakout box. Leave PCM disconnected. Connect a test light between test pins No. 8 and 37 at breakout box. Turn ignition on, engine off. Observe test light, and shake, wiggle and bend the following circuits. Fuel pump monitor (FPM) circuit. Power-to-fuel pump circuit. Fuel pump ground and HFP relay circuits between HFP relay and VCRM. To simulate road shock, lightly tap on Inertia Fuel Shutoff (IFS) switch, VCRM and HFP relay. If a fault is detected, test light will turn off indicating an open circuit. Test light will also turn off and fuel pump will run, if a short to power or HFP circuit short to ground is detected. If a fault is detected, isolate fault and repair wiring as necessary. Remove breakout box. Reconnect all components. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If a fault is not detected, go to step 158). NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 156) to step 158). No test procedures have been omitted. NOTE: Due to internal circuitry of PCM, an intermittent short to power in left HO2S signal may produce a Continuous Memory Code 524, 542 or 543.
101. 158) Check For Short To Power In Left HO2S Turn ignition off. Install breakout box. Leave PCM disconnected. Connect test light between test pins No. 40 and 43 at breakout box. Turn ignition on. Observe test light and shake, wiggle and bend Red/Black wire between left HO2S and PCM connector. To simulate road shock, lightly tap on left HO2S. If a fault is detected, test light will turn on bright, indicating a short to power. If a short to power is detected, isolate fault and repair wiring as necessary. Remove breakout box. Reconnect all components. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If a short to power is not detected, fault is intermittent and cannot be duplicated at this time. Testing is complete. Reconnect all components. For further diagnosis, see the «TESTS W/O CODES»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wo-codes) article. NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 158) to step 160). No test procedures have been omitted.
102. 160) Lack Of Power/Hard Start; Check HFP Relay Operation Turn ignition off. Disconnect HFP relay. Relay is located in engine compartment fuse block. Measure voltage between negative battery terminal and B(+) terminal at HFP relay vehicle wiring harness connector. (Scheme 72) Turn ignition on. Measure voltage between IGN START/RUN terminal at HFP relay connector and negative battery terminal. If both voltage readings are more than 10.5 volts, go to next step. If any reading is 10.5 volts or less, repair open in B(+) or IGN START/RUN circuit. Also, ensure all related fuses are good. After repair has been completed, reconnect all components. Recheck system operation.
103. 161) Check Power-To-Fuel Pump Circuit Continuity Turn ignition off. Disconnect HFP relay connector. Measure resistance between negative battery terminal and POWER-TO-FUEL PUMP terminal at HFP relay vehicle wiring harness connector. (Scheme 72) If resistance is less than 10 ohms, go to next step. If resistance is 10 ohms or more, repair open in power-to-fuel pump circuit between HFP relay and splice to main power-to-fuel pump circuit. After repair is completed, reconnect all components. Recheck system operation.
104. 162) Check VCRM & HFP Circuit Operation Turn ignition off. Reconnect HFP relay. Start engine. Run engine until normal operating temperature is reached. Turn ignition off. Disconnect HFP relay. Connect DVOM between terminals B(+) and HFP at HFP relay vehicle wiring harness connector. (Scheme 72) Ensure all accessories are off. Observe DVOM and start engine. Within 10 seconds of start, record voltage reading. Observe DVOM and allow engine to idle for 2 minutes. If voltage reading decreases 0.4 volt or more within 2 minutes of running engine, VCRM and HFP circuits are okay. Turn ignition off and go to next step. If voltage reading does not decrease a minimum of 0.4 volt within 2 minutes of running engine, turn ignition off. Go to step 165).
105. 163) Check HFP Relay Turn ignition off. Disconnect HFP relay. Connect a jumper wire between positive battery terminal and IGN START/RUN terminal at HFP relay. (Scheme 74) Connect one end of another jumper wire to HFP terminal at HFP relay. Listen to HFP relay and touch remaining end of jumper wire to negative battery terminal. If relay clicks, relay is working properly. Remove jumper wires and reconnect HFP relay. If relay does not click, replace relay. Reconnect all components. Recheck system operation. (Scheme 74): Identifying High Speed Fuel Pump (HFP) Relay Terminals NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 163) to step 165). No test procedures have been omitted.
106. 165) Check HFP Circuit Continuity Turn ignition off. Disconnect HFP relay. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Measure resistance between terminal No. 10 (Brown/White wire) at VCRM wiring harness connector and HFP terminal at HFP relay connector. (Scheme 72) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in HFP circuit (Brown/White wire). Reconnect all components. Recheck system operation.
107. 166) Check For Short To Power In HFP Circuit Turn ignition off. Ensure VCRM and HFP relay are disconnected. Turn ignition on. Measure voltage between negative battery terminal and HFP terminal at HFP relay connector. (Scheme 72) If voltage is less than one volt, go to next step. If voltage is one volt or more, repair short to power in HFP circuit. Reconnect all components. Recheck system operation.
108. 167) Check For Short To Ground In HFP Circuit Turn ignition off. Ensure VCRM and HFP relay are disconnected. Measure resistance between negative battery terminal and HFP terminal at HFP relay connector. (Scheme 72) If resistance is more than 10,000 ohms, replace VCRM. Reconnect all components. Recheck system operation. If resistance is 10,000 ohms or less, repair short to ground in HFP circuit. Reconnect all components. Recheck system operation. NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 167) to step 170). No test procedures have been omitted.
109. 170) KOEO & Continuous Memory Code 587: Check Wiring Harness Code 587 indicates a Data Link Connector (DLC) failure between PCM and VCRM. DLC includes data (+) and data (-) circuits. Following are possible causes for this fault. Open Or Short In Data (+) Or Data (-) Circuits Damaged VCRM Damaged PCM Check wiring harness containing data (+) (Tan/Orange wire) and data (-) (Pink/Light Blue wire) circuits between VCRM and PCM connectors for proper installation, location (not close to high voltage wires) and for aftermarket modifications. Relocate or repair wiring as necessary. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If KOEO Code 587 is present and wiring is okay, go to next step. If Continuous Memory Code 587 is present and wiring is okay, go to step 180).
110. 171) Check Data (+) & Data (-) Circuit Short To Power Turn ignition off. Disconnect any test equipment connected to Data Link Connector (DLC). Leave equipment disconnected throughout procedure unless otherwise instructed. Disconnect and inspect VCRM and PCM connectors. Clean or repair connectors as necessary. Install breakout box. Turn ignition on. Leave PCM disconnected. Measure voltage between test pin No. 18 and 40 at breakout box. Also, measure voltage between test pin No. 19 and 40 at breakout box. If both voltage readings are less than 1.0 volt, go to next step. If any reading is 1.0 volt or more, repair short to power in Tan/Orange and/or Pink/Light Blue wire. Reconnect all components. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
111. 172) Check For Short In Data (+) & Data (-) Circuits Turn ignition off. Install breakout box. Disconnect PCM and VCRM. Measure resistance between test pins No. 18 and 40, and pins No. 19 and 40 at breakout box. Also, measure resistance between test pins No. 18 and 19. If all readings are more than 10,000 ohms, go to next step. If any reading 10,000 ohms or less, repair short circuit in data (+) (Tan/Orange wire) and/or data (-) (Pink/Light Blue wire) circuits. Remove breakout box. Reconnect all components. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
112. 173) Check Data (+) & Data (-) Circuit Continuity Turn ignition off. Disconnect and inspect VCRM and PCM connectors. Clean or repair connectors as necessary. Install breakout box. Turn ignition on. Leave PCM disconnected. Measure resistance between test pin No. 18 at breakout box and terminal No. 21 (Tan/Orange wire) at VCRM wiring harness connector. Also, measure resistance between test pin No. 19 at breakout box and terminal No. 23 (Pink/Light Blue wire) at VCRM wiring harness connector. If both resistance readings are less than 5.0 ohms, go to next step. If any reading is 5.0 ohms or more, repair open in Tan/Orange and/or Pink/Light Blue wire. Reconnect all components. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
113. 174) Check Data Communication Link (DCL) In VCRM Turn ignition off. Ensure all test equipment is disconnected from DLC. Ensure breakout box is installed and PCM is disconnected. Reconnect VCRM connector. Turn ignition on. Measure voltage between test pins No. 18 (data (+) circuit) and No. 19 (data (-) circuit) at breakout box. If voltage is 3.5-5.3 volts, go to next step. If voltage is not 3.5-5.3 volts, turn ignition off. Replace VCRM. Remove breakout box. Reconnect all components. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
114. 175) Check Data (-) Circuit In VCRM Turn ignition off. Ensure all test equipment is disconnected from Data Link Connector (DLC), breakout box is installed and PCM is disconnected. With VCRM connected, measure resistance between test pins No. 19 (data (-) circuit) and No. 40 (GND) at breakout box. If resistance is 1500-2500 ohms, go to next step. If resistance is not 1500-2500 ohms, turn ignition off. Replace VCRM. Remove breakout box. Reconnect all components. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off.
115. 176) Verify That PCM Can Communicate On DCL The purpose of this test is to verify that PCM can communicate on DCL. A scan tool is required for this test step. Follow manufacturer's instructions to hook up equipment. Turn ignition off. Remove breakout box. Reconnect PCM. Connect scan tool to DLC. Start engine. While in DCL display, view RPM Parameter Identification (PID). Monitor RPM, and change engine speed. If RPM PID is displayed and changes with engine speed, go to next step. If RPM PID is not displayed or is displayed but does not change with engine speed, go to step 179).
116. 177) Verify DCL In VCRM Turn ignition off. Ensure PCM and VCRM are connected. Turn A/C off. Enter output state Diagnostic Test Mode (DTM). See «OUTPUT STATE DIAGNOSTIC TEST MODE (DTM)»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__output-state-diagnostic-test-mode-dtm) under ADDITIONAL SYSTEM FUNCTIONS. Turn outputs off. Depress and hold throttle near Wide Open Throttle (WOT) until Malfunction Indicator Light (MIL) flashes once (about 10 seconds). Release throttle. Cooling fan should turn on. Depress throttle to turn cooling fan off. If cooling fan turns on and off as requested, exit output state DTM. Go to next step. NOTE: Cooling fan can only be cycled once during output state DTM. To retest, exit and re-enter output state DTM. If cooling fan does not turn on and off as requested, ensure output state DTM is operating properly. MIL should flash when throttle is depressed and released. If MIL does not flash, check throttle linkage and DLC connections. If output state DTM is operating properly, replace VCRM. Reconnect all components. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
117. 178) Check DCL In VCRM Turn ignition off. Ensure PCM and VCRM are connected. Disconnect cooling fan. Ensure A/C and defroster are off. Perform «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test). If KOEO Code 582 is present, reconnect cooling fan. No problem is indicated at this time. Data (+) and data (-) circuits test okay and DCL is operational in PCM. Reconnect all components. If KOEO Code 582 is not present, allow time for engine to cool down to verify that cooling fan does to come on. After engine is cooled, start engine and wait 10 seconds. Turn ignition off. Repeat «KOEO SELF-TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv__koeo-self-test). If KOEO Code 582 is still not present, replace VCRM. Reconnect cooling fan. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv).
118. 179) Check Data (+) & Data (-) Circuit Continuity To DCL Turn ignition off. Install breakout box. Leave PCM disconnected. Disconnect scan tool from DLC. Measure resistance between test pin No. 18 at breakout box and data (+) terminal (Tan/Orange wire) at DLC. see scheme 64 Also, measure resistance between pin No. 19 at breakout box and data (-) terminal (Pink/Light Blue wire) at DLC. If both readings are less than 5 ohms, replace PCM. Remove breakout box. Reconnect all components. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If any reading is 5 ohms or more, repair open circuit as necessary. After repair is complete, return to step 176). see scheme 64: Identifying Data Link Connector (DLC) Terminals
119. 180) Check For Intermittent In Data (+) & Data (-) Circuits Perform test while cooling fan is off. Start engine. Ensure A/C is off. Shake, wiggle and bend data (+) (Tan/Orange wire) and data (-) (Pink/Light Blue wire) circuits between PCM and VCRM connectors. To simulate road shock, lightly tap on VCRM. VCRM will turn fan on if DLC fault is detected. If cooling fan turns on, for other than normal operation, isolate fault and repair wiring as necessary. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If cooling fan does not turn on, go to next step.
120. 181) Check For Intermittent Short In Data (+) & Data (-) Circuits Turn ignition off. Disconnect test equipment from Data Link Connector (DLC). Disconnect and inspect PCM and VCRM connectors. Clean or repair connectors as necessary. Install breakout box. Leave PCM and VCRM disconnected. Connect a jumper wire between data (+) (Tan/Orange wire) and data (-) (Pink/Light Blue wire) circuits at DLC. see scheme 64 Connect test light between test pins No. 19 and 37 at breakout box. Observe test light, and shake, wiggle and bend data (+) (Tan/Orange wire) and data (-) (Pink/Light Blue wire) circuits between PCM and VCRM connectors. If a fault is detected, test light will turn on, indicating a short to ground. Disconnect jumper wire. Reconnect test light between test pins No. 19 and 40 at breakout box. Observe test light, and shake, wiggle and bend data (+) (Tan/Orange wire) and data (-) (Pink/Light Blue wire) circuits between PCM and VCRM connectors. If a fault is detected, test light will turn on, indicating a short to power. If a short is detected, isolate fault and repair wiring as necessary. Remove breakout box, and reconnect all components. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If a short is not detected, go to next step.
121. 182) Check For Intermittent Open In Data (+) & Data (-) Circuits Turn ignition off. Ensure breakout box is installed and PCM and VCRM are disconnected. Connect a jumper wire between terminals No. 21 (Tan/Orange wire) and No. 23 (Pink/Light Blue wire) at VCRM connector. Ensure jumper wire does not contact other terminals at VCRM connector. Using an ohmmeter, measure resistance between test pins No. 18 and 19 at breakout box. Observe ohmmeter, and shake, wiggle and bend data (+) (Tan/Orange wire) and data (-) (Pink/Light Blue wire) circuits between PCM and VCRM connectors. If reading increases to more than 5 ohms at any time, isolate and repair open circuit and repair wiring as necessary. Remove jumper wire and breakout box. Reconnect all components. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat «QUICK TEST»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv). If reading stays at 5 ohms or less, fault is intermittent and cannot be duplicated at this time. Testing is complete. Remove jumper wire and breakout box. Reconnect all components.

See also:
• BASIC TESTING - 4.6L
• TESTS W/O CODES
• COMPUTER RELEARN PROCEDURES
• SYSTEM/COMPONENT TESTS
• FUEL PRESSURE SPECIFICATIONS
• QUICK TEST
• CLEARING CODES
• KOEO SELF-TEST
• CIRCUIT TEST AC
• CONTINUOUS MONITOR MODE (WIGGLE TEST)
• PRELIMINARY INSTRUCTIONS (A/T)
• PRELIMINARY INSTRUCTIONS (M/T)
• CIRCUIT TEST H
• OUTPUT STATE DIAGNOSTIC TEST MODE (DTM)