Engine Controls - Tests W/codes - Eec (1.8L): Other Mercury Tracer I

Hard Failures

Hard failures cause Malfunction Indicator Light (MIL) to come on and trouble codes to be set in Powertrain Control Module (PCM) memory. Trouble code remains until problem is repaired or PCM memory is cleared. After trouble code has been identified, use code reference charts to determine which circuit tests to perform.

If a sensor fails, PCM will use a substitute value in its calculations to continue engine operation. PCM can estimate failed sensor values based on feedback from working sensors. In this condition, known as fail-safe, vehicle runs but driveability will not be optimum.

Intermittent Failures

Intermittent failures may cause Malfunction Indicator Light (MIL) to flicker or glow. Light will go out after intermittent fault goes away. These faults indicate that a defect may or may not be present at time of testing, however, corresponding trouble code will be retained in PCM memory.

If fault remains for 40 key cycles, trouble code will be entered into permanent PCM memory. Intermittent failures may be caused by a sensor, connector or wiring problems. See INTERMITTENTS in the TESTS W/O CODES - EEC (1.8L) article.

Visual Check & Vehicle Preparation

Before hooking up any equipment to diagnose EEC system, visually check following and perform preparation procedures

1. Perform all necessary safety precautions to prevent personal injury or vehicle damage.
2. Block drive wheels. Set parking brake. Place shift lever in Park (A/T) or Neutral (M/T). DO NOT move shift lever during test unless specifically directed to do so.
3. Check condition of air cleaner and air ducting.
4. Check all vacuum hoses for leaks, restrictions and proper routing.
5. Check EEC system wiring harness connections for corrosion, damaged pins, loose wires and improper routing.
6. Check PCM, sensors and actuators for physical damage.
7. Check engine coolant and oil level.
8. Check battery condition. Turn off all lights and accessories. Ensure vehicle doors are closed when measuring voltage.
9. Ensure engine is at operating temperature.
10. Check exhaust system for leaks.

EQUIPMENT HOOKUP

Note. After performing equipment hookup, follow appropriate quick test procedures based on type of equipment being used. See QUICK TEST.

Using Analog Volt-Ohmmeter (VOM)

1) Turn ignition off. Locate Data Link Connector (DLC). see scheme 1 Connect positive (+) lead of VOM to PCM STO terminal at DLC and negative (-) test lead to engine ground (GND). (Scheme 5) Set VOM to 0-20V DC range.

2) Connect a jumper wire between ground and PCM STI terminal of DLC. (Scheme 5)

Using Malfunction Indicator Light (MIL)

Check MIL operation. Turn ignition switch to ON position. If MIL is on, MIL circuit is okay. Go to next step. If MIL is off, go to CIRCUIT TEST MIL. After performing CIRCUIT TEST MIL, return to this procedure. Connect a jumper wire between ground and PCM STI terminal of DLC. (Scheme 5)

Using Super Star II Tester

1) Turn ignition off. Connect color-coded adapter cable leads to Super Star II tester. Connect service adapter cables to vehicle Data Link Connector (DLC). see scheme 1

2) Connect Super MECS Adapter (007-00049 or 007-00052) between adapter cables and vehicle DLC. Slide adapter switch to EEC/MECS position. Slide Super Star II tester switch to EEC/MECS position.

Using New Generation Star Tester

1) Turn ignition off. Connect power cable and data cable to scan tester. Connect Rotunda Super MECS Adapter (007-00052) to scan tester data cable.

2) Plug matching connector on Super MECS adapter into vehicle DLC. Slide switch on Super MECS adapter to PCM position. Plug power cable on scan tester into cigar lighter or use battery adapter.

Using Aftermarket Scan Tester

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

Scheme 5

Using Analog VOM

Watch voltmeter and count needle sweeps (between 0-12 volts) to read code. Pay careful attention to length of pauses in order to read codes correctly. A 2-second pause occurs between digits in a code. A 4-second pause occurs at end of each code. (Scheme 5)

Using MIL/CHECK ENGINE light

Service codes are displayed as flashes. Code flashes are read in the same manner as with using an analog VOM.

Using New Generation Star or Super Star II Scan Tester

Codes will be displayed digitally. KOEO codes include hard and intermittent failures. To determine failure type (hard or intermittent), record and clear codes stored in PCM memory. Operate vehicle, and repeat KOEO self-test. Codes that reappear immediately are hard failures. Codes that do not reappear are intermittent failures.

Repair hard failures in order of code appearance before performing KOER self-test. Use CODE REFERENCE table to determine circuit test to perform. Clear codes from PCM memory after they have been recorded and/or faults have been repaired. See CLEARING CODES. When performing quick test, if no trouble codes are found during KOEO self-test, proceed to KOER self-test. Using Scan Tester, follow equipment manufacturer's instructions to read codes.

Scheme 6

CLEARING CODES

To clear trouble codes, deactivate self-test by disconnecting jumper wire from PCM STI terminal at Data Link Connector (DLC). Disconnect negative (-) battery cable. Depress brake pedal for 5-10 seconds. All hard codes and intermittent codes will be erased from PCM memory.

Analog VOM Or MIL

1) To perform Key On Engine Off (KOEO) self-test, turn ignition switch to ON position and observe voltmeter (or MIL). Count voltmeter needle sweeps (or MIL flashes). If codes are not present, go to step 3). If codes are present, record codes, turn ignition off and go to next step.

Note. If a code repeats immediately after codes have been cleared, it is considered a "hard fault". If a code does not immediately repeat, the fault is considered "intermittent" and is not failing during self-testing. See INTERMITTENTS in the TESTS W/O CODES - EEC (1.8L) article.

2) Erase codes from PCM memory. See CLEARING CODES. Repeat step 1). If no codes are present go to next step. If any codes are present, refer to CODE REFERENCE table to determine circuit test to perform. After performing repair, return to start of quick test.

3) To perform Key On Engine Running (KOER) self-test, remove jumper wire from DLC. Start engine and run at 3000 RPM for 3 minutes. Reconnect jumper wire at DLC. Turn ignition off, then restart engine and run at idle. Read codes.

4) If no codes are present, go to ANALOG VOM OR MIL under SWITCH MONITOR TEST. If codes are present, refer to CODE REFERENCE table to determine circuit test to perform. If engine does not start, check for codes and repair as necessary. If engine does not start and no codes are present, go to the BASIC TESTING - 1.8L article.

Super Star II Tester

1) To initiate KOEO self-test, depress center button to TEST position. Turn Super Star II tester on. Tester should display 888 for 2 seconds when activated. Turn ignition switch to ON position.

2) Release and then depress center button to TEST position. After all codes have been received by tester, release center button.

3) Read and record all codes in tester memory, and then go to next step. If no codes exist, go to step 5).

4) Erase codes from PCM memory. See CLEARING CODES. Repeat steps 1) and 2). If code does not reappear, fault is intermittent. Go to next step to begin KOER self-test. If code reappears, indicating hard fault, repair fault as necessary. Refer to CODE REFERENCE table to determine circuit test to perform. After performing repair, return to beginning of QUICK TEST. Repeat quick test until all faults are corrected and no hard codes exist.

5) To initiate KOER self-test, ensure center button on Super Star II tester is released and tester is OFF. Start and run engine at 2000 RPM for 3 minutes to ensure HO2S/O2S sensor is operating. Turn Super Star II tester on. Depress center button. Turn ignition off. Start engine and allow it to idle.

6) To activate KOER self-test, release and then reset center button to TEST position. Record all codes displayed. Refer to CODE REFERENCE table to determine circuit test to perform. If no code is displayed, go to SUPER STAR II TESTER under SWITCH MONITOR TEST.

New Generation Star Tester or Aftermarket Scan Tester

See manufacturer's instructions provided with tester.

CODE REFERENCE

1) Turn engine off and allow to cool. Turn all accessories off. Disconnect PCM STI jumper from ground. Place shift lever in Park (A/T) or Neutral (M/T).

2) Reconnect jumper wire between ground and PCM STI terminal at Data Link Connector (DLC). Using VOM, connect positive (+) lead to SML terminal at DLC. (Scheme 6) Connect negative (-) lead to engine ground.

3) Turn ignition on. Operate input switches individually while watching VOM (or MIL). See SWITCH MONITOR TEST SPECIFICATIONS table. Ensure input switch is deactivated after each test. Leaving switch on while testing another switch may produce false results and cause misdiagnosis.

4) If input switch fails test (reading on VOM is not as specified or MIL does not blink), perform related circuit test. See SWITCH MONITOR TEST SPECIFICATIONS table. If all input devices fail, check Switch Monitor Light (SML) circuit. See CIRCUIT TEST SML. If all input devices test okay and no code is stored in PCM memory, EEC self-diagnostic system test is complete.

SWITCH MONITOR TEST SPECIFICATIONS

1) Turn engine off and allow it to cool. Turn all accessories off. Connect tester. See SUPER STAR II TESTER under QUICK TEST. Ensure tester center button is released.

2) Place shift lever in Park (A/T) or Neutral (M/T). Turn ignition on. Turn tester on, and set center button to TEST position. Observe LED indication as each input switch is tested. See SWITCH MONITOR TEST SPECIFICATIONS table.

3) Operate each switch individually. Turn off after test. Leaving switch on while testing another switch may produce false results and cause misdiagnosis. If input switch circuit fails test (reading on Super Star II tester is not as indicated), perform related circuit test. See SWITCH MONITOR TEST SPECIFICATIONS table.

4) If all input devices fail, check Switch Monitor Light (SML) circuit. See CIRCUIT TEST SML . If all input devices test okay and no code is stored in PCM memory, EEC system test is complete.

New Generation Star Tester

See manufacturer's instructions provided with tester.

SUMMARY

If no hard fault codes are present, driveability symptoms exist or intermittent codes exist, proceed to the appropriate TESTS W/O CODES - EEC (1.8L) article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.

CIRCUIT TESTS

Note. PCM is located forward of center console. For identification of PCM connector terminals (Scheme 7)or (Scheme 8).

Scheme 7

Scheme 8

HOW TO USE CIRCUIT TESTS

1) Do not perform any circuit test unless specifically instructed by a procedure under QUICK TEST or SWITCH MONITOR TEST. Ensure all non-EEC related faults are corrected. Follow each test step in order until fault is found. When more than one code is received, start with first code displayed.

2) Use circuit tests to check electrical circuits before replacing sensors or any other components. Always test circuits for continuity between sensor and PCM. Test all circuits for short to power, opens or short to ground.

3) DO NOT connect any test light or measure voltage or resistance at PCM unless specified in testing procedure. DO NOT pierce wiring. If backprobing is specified, always backprobe harness side of connector. DO NOT probe connector side.

4) Isolate both ends of circuit and turn ignition off whenever checking for shorts or continuity, unless specified otherwise. Disconnect solenoids and switches before checking circuit continuity or energizing solenoids.

Barometric Pressure Sensor

Note. Enter this test only when Code 14 is displayed during self-test procedures (KOEO or KOER) or when directed here from another circuit test. To prevent unnecessary replacement of components, check atmospheric pressure (barometer reading). If atmospheric pressure is unusually high or low, recheck when atmospheric pressure stabilizes.

Note. Barometric pressure sensor is built into PCM and cannot be replaced separately. If Code 14 appears repeatedly after clearing codes, replace PCM.

Visually check all wiring, connectors and components for evidence of damage, shorting or looseness. If a fault is found, repair as necessary. If no fault is found, erase codes from memory. Perform KOEO and KOER self-tests. See QUICK TEST. If Code 14 continues to appear, replace PCM.

Crankshaft Position Sensor

Note. Enter this test only when Code 02 is displayed during self-test procedures (KOEO or KOER) or when directed here from another circuit test. This test is intended to diagnose CKP circuit only.

CIRCUIT PIN IDENTIFICATION

1) Check System Integrity Visually check all wiring, connectors and components for evidence of damage, shorting or looseness. If a fault is found, repair as necessary. If no fault is found, go to next step.

2) Check VPWR To Distributor Turn ignition off. Disconnect distributor connector. Turn ignition on. Measure voltage between ground and distributor VPWR wire. If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, perform CIRCUIT TEST VPWR. If results of CIRCUIT TEST VPWR are okay, repair open in VPWR wire to distributor.

3) Check Distributor Ground Ensure ignition is off and distributor is disconnected. Measure resistance between distributor GND wire and ground. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in distributor GND wire.

4) Check Distributor To PCM Wires Ensure ignition is off and distributor is disconnected. Install breakout box, leaving PCM disconnected. Measure and record resistance between CKP test pin at breakout box and CKP terminal at distributor connector. (Scheme 9) Measure and record resistance between ground and CKP test pin at breakout box. If resistance is less than 5 ohms between CKP test pin and CKP terminal at distributor connector and more than 10,000 ohms between ground and CKP test pin, replace CKP sensor. If resistance is not as specified, repair CKP wire between distributor connector and PCM.

Identifying Distributor Connector Terminals. Scheme 9

Camshaft Position Sensor

Note. Enter this test only when Code 03 is displayed during self-test procedures (KOEO or KOER) or when directed here from another circuit test. This test is intended to diagnose CMP circuit only.

Note. CMP sensor is integrated into the distributor assembly.

CIRCUIT PIN IDENTIFICATION

1) Check System Integrity Visually check all wiring, connectors and components for evidence of damage, shorting or looseness. If a fault is found, repair as necessary. If no fault is found, go to next step.

2) Check CMP Signal Turn ignition off. Install breakout box. Connect PCM to breakout box. Measure voltage at CMP test pin at breakout box while bumping starter. If voltage fluctuates between zero and 5 volts, circuit is okay. If no other problem or code is found, replace PCM. If voltage does not fluctuate between zero and 5 volts, go to next step.

3) Check VPWR To Distributor Ensure ignition is off. Disconnect distributor connector. Turn ignition on. Measure voltage at VPWR wire at distributor connector. If voltage is more than 10 volts, go to next step. If voltage is less than 10 volts, go to CIRCUIT TEST VPWR. If VPWR circuit is okay, repair VPWR wire to distributor.

4) Check Distributor Ground Turn ignition off. Ensure distributor is disconnected. Measure resistance of GND wire between distributor connector and ground. If resistance is less than 5 ohms, go to next step. If resistance is more than 5 ohms, repair open GND wire.

5) Check For Open CMP Wire Ensure ignition is off. With breakout box installed, disconnect PCM connectors. Measure resistance of CMP wire between ground and CMP test pin at breakout box. If resistance is less than 5 ohms, go to next step. If resistance is greater than 5 ohms, repair open CMP circuit wire.

6) Check For Short In CMP Wire With breakout box installed and PCM and distributor connectors disconnected, measure resistance of CMP wire between ground and CMP test pin 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 CMP wire.

7) Check For Short In Harness Turn ignition off. Disconnect distributor and PCM connector. Measure resistance between CMP wire and all other wires in distributor harness connector. (Scheme 9) If all resistances are greater than 10,000 ohms, replace distributor. If any resistance reading is less than 10,000 ohms repair shorted wire(s) in question.

Engine Coolant Temperature Sensor

Note. Enter this test only when a Code 09 is displayed during self-test procedures (KOEO or KOER) or when directed here from another circuit test. To prevent unnecessary diagnosis, inspect coolant level, oil level, cooling fan, thermostat and airflow to radiator for obstruction before electronic testing. This test is intended to diagnose ECT circuit only.

CIRCUIT PIN IDENTIFICATION

1) Check System Integrity Visually check all wiring, connectors and components for evidence of damage, shorting or looseness. If a fault is found, repair as necessary. If no fault is found, go to next step.

2) Check ECT Sensor Resistance Run engine until engine coolant reaches temperatures specified. See RESISTANCE SPECIFICATIONS (ECT SENSOR) table. Monitor temperature at ECT sensor (near thermostat housing) using Rotunda Digital Thermometer (055-00100) or equivalent. Turn ignition off. Install breakout box, leaving PCM disconnected. Measure resistance between ECT and SIG RTN test terminals at breakout box. Compare readings with RESISTANCE SPECIFICATIONS (ECT SENSOR) table. If resistance is not as specified, go to next step. If resistance is as specified, ECT circuit is okay. If no other problem or code is found, replace PCM.

RESISTANCE SPECIFICATIONS

3) Check ECT Circuit Turn ignition off. With breakout box installed and PCM disconnected, disconnect ECT sensor connector. Measure and record resistance between ECT test pin at breakout box and ECT terminal at sensor connector. (Scheme 10) If resistance is less than 5 ohms, go to next step. If resistance is greater than 5 ohms, repair open wire between ECT sensor connector and PCM.

4) Ensure no continuity exists between ECT test pin at breakout box and ground or between ECT test pin at breakout box and SIG RTN test pin at breakout box. If continuity is present between ECT circuit and any other circuit, repair ECT wire between ECT sensor connector and PCM. If no continuity is present between ECT circuit and any other circuit go to next step.

5) Check SIG RTN Circuit Ensure ignition is off and ECT sensor is disconnected. With breakout box installed and PCM disconnected, measure resistance between SIG RTN test pin at breakout box and SIG RTN terminal at ECT sensor connector. (Scheme 10) If resistance is less than 5 ohms, replace ECT sensor. If resistance is 5 ohms or more, repair SIG RTN wire between ECT sensor connector and PCM.

Identifying ECT Connector Terminals. Scheme 10

Heated Oxygen Sensor

CIRCUIT PIN IDENTIFICATION

Note. This test is intended to diagnose HO2S circuit only. Perform this test only when Code 15, 17, 23 or 24 is displayed during self-test procedures (KOEO or KOER). Code 15 indicates a continuously low HO2S signal voltage. Code 17 indicates a HO2S signal voltage does not change. This could indicate a problem other than HO2S circuit (no duty cycle variation).

1) Check System Integrity Visually check wiring, connector and component for evidence of damage, shorting or looseness. If a fault is found, repair as necessary. If no fault is found, go to next step.

2) Check HO2S Sensor Output Voltage Turn ignition off, and install breakout box. Connect PCM to breakout box. Warm engine to normal operating temperature. Measure voltage at HO2S test pin at breakout box. Compare voltage reading with HO2S VOLTAGE SPECIFICATIONS table. If voltage readings are as specified, go to step 6). If readings are not as specified, go to next step.

HO2S VOLTAGE SPECIFICATIONS

Note. A break in step numbering sequence occurs at this point. No test procedures have been omitted.

4) Check For Open HO2S Wire Ensure ignition is off and HO2S is disconnected. With breakout box installed and PCM disconnected, measure resistance between HO2S test pin at breakout box and HO2S terminal at HO2S connector. (Scheme 11) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in HO2S wire.

5) Check For Short In HO2S Wire Ensure ignition is off and HO2S is disconnected. With breakout box installed and PCM disconnected, measure resistance between ground and HO2S test pin at breakout box. If resistance is more than 10,000 ohms, replace HO2S. If resistance is 10,000 ohms or less, repair short to ground in HO2S wire.

6) Check HO2S Heater Resistance If voltage readings were okay in step 2), turn ignition off. Disconnect HO2S connector. With sensor at 68°F (20°C), measure resistance between terminals PWR and GND at HO2S. (Scheme 11) If resistance is about 6 ohms, go to next step. If resistance is not about 6 ohms, replace HO2S.

7) Check Power To HO2S Sensor Heater With HO2S disconnected, turn ignition on. Measure voltage at PWR terminal at HO2S connector. (Scheme 11) If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, go to CIRCUIT TEST VPWR. If VPWR circuit is okay, repair VPWR wire to HO2S.

8) Check HO2S Heater Ground With HO2S disconnected, measure resistance of HO2S heater GND wire between ground and HO2S connector. If resistance is less than 5 ohms, HO2S circuit is okay. If no other problem or code is found, replace PCM. If resistance is 5 ohms or more, repair sensor heater GND wire.

Identifying HO2S Circuit & Connector Terminals. Scheme 11

Intake Air Temperature Sensor

Note. Enter this test only when a Code 10 is displayed during self-test procedures (KOEO or KOER) or when directed here from another circuit test. This test is intended to diagnose IAT circuit only.

CIRCUIT PIN IDENTIFICATION

1) Check System Integrity Visually check all wiring, connectors and components for evidence of damage, shorting or looseness. If a fault is found, repair as necessary. If no fault is found, go to next step.

2) Check IAT Resistance Turn ignition off. Install breakout box, leaving PCM disconnected. Access IAT sensor. Sensor is located in Volume Airflow (VAF) meter. Monitor temperature at IAT sensor using Rotunda Digital Thermometer (055-00100) or equivalent. Measure resistance between IAT and SIG RTN test pins at breakout box. Heat sensor using heat gun. Compare readings with RESISTANCE SPECIFICATIONS (IAT SENSOR) table. If resistance is not as specified, go to next step. If resistance is as specified, IAT circuit is okay. If no other problem or code is found, replace PCM.

RESISTANCE SPECIFICATIONS

3) Check For Open IAT Wire Ensure ignition is off, breakout box is installed and PCM is disconnected. Disconnect VAF sensor connector. Measure resistance between IAT test pin at breakout box and IAT terminal at VAF or MC-VAF sensor connector. (Scheme 13) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open IAT wire.

4) Check For Short In IAT Wire Ensure ignition is off, breakout box is installed and PCM is disconnected. Disconnect VAF sensor connector. Measure resistance between ground and IAT test pin at breakout box. If resistance is more than 10,000 ohms, go to step 6).

Note. A break in step numbering sequence occurs at this point. No test procedures have been omitted.

6) Check IAT Sensor SIG RTN Ensure ignition is off. Ensure breakout box is installed (PCM disconnected) and VAF sensor is disconnected. Measure resistance between SIG RTN test pin at breakout box and SIG RTN terminal at VAF sensor connector. (Scheme 13) If resistance is 5 ohms or more, repair IAT sensor SIG RTN wire. If resistance is less than 5 ohms, replace VAF sensor.

Identifying IAT Sensor Circuit. Scheme 12

Identifying IAT Connector Terminals. Scheme 13

Malfunction Indicator Light

Note. Enter this test only when instructed by QUICK TEST. This test is intended to diagnose MIL circuit only.

CIRCUIT PIN IDENTIFICATION

1) Check System Integrity Visually check all wiring, connectors and components for evidence of damage, shorting or looseness. If fault is found, repair as necessary. If no fault is found, go to next step.

2) Check MIL Operation Turn ignition off. Install breakout box, leaving PCM disconnected. Turn ignition on. Ground STO/MIL test pin at breakout box. If MIL is on, MIL circuit is okay. If codes do not flash on MIL during QUICK TEST or MIL never comes on, replace PCM. If MIL is off, go to next step.

3) Check MIL Bulb Turn ignition off. Remove instrument cluster. Remove and inspect MIL bulb. Replace bulb as necessary. If bulb is okay, go to next step.

4) Check For Open MIL Wire Turn ignition off. Disconnect instrument cluster connector. Ensure ignition is off, breakout box is installed and PCM is disconnected. Measure resistance between STO/MIL test pin at breakout box and STO/MIL terminal at instrument cluster connector. (Scheme 14) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in STO/MIL wire.

5) Check For Short In MIL Wire Ensure ignition is off, breakout box is installed, and PCM and instrument cluster connectors are disconnected. Measure resistance between ground and STO/MIL test pin at breakout box. If resistance is more than 10,000 ohms, replace instrument cluster printed circuit board. If resistance is 10,000 ohms or less, repair short to ground in MIL wire.

Identifying Instrument Cluster Connector Terminals. Scheme 14

Power & Ground Check

Note. Enter this test only when directed here by CIRCUIT TEST STO or by another test. This test is intended to diagnose Keep Alive Power (KAPWR) and Ground (GND) circuits.

CIRCUIT PIN IDENTIFICATION

1) Check System Integrity Visually check all wiring, connectors and components for evidence of damage, shorting or looseness. If fault is found, repair as necessary. If no fault is found, go to next step.

2) Check Voltage Turn ignition off. Install breakout box, leaving PCM disconnected. Measure voltage at KAPWR test pin at breakout box. If reading is about battery voltage, go to next step. If reading is less than battery voltage, repair wire as necessary.

3) Check Grounds Ensure ignition is off, breakout box is installed and PCM is disconnected. Measure resistance between ground and GND test pin at breakout box. Repeat test for each ground wire. If resistance is less than 5 ohms, replace PCM. If resistance is 5 ohms or more, repair open ground wire.

Relay Output Check

Note. Enter this test when a Code 67 is displayed during self-test procedures (KOEO or KOER) or when directed here from another circuit test or SWITCH MONITOR TEST. This test is intended to diagnose the Wide Open Throttle A/C Cutoff Relay (WAC).

CIRCUIT PIN IDENTIFICATION

1) Check System Integrity Visually check all wiring, connectors and components for evidence of damage, shorting or looseness. If fault is found, repair as necessary. If no fault is found, go to next step.

2) Perform Relay Click Test Turn ignition off. Install breakout box (PCM disconnected). Turn ignition on. Listen for relay to click while grounding appropriate relay test pin at breakout box. If relay clicks, relay is okay. If relay does not click, go to next step.

3) Check For Open Relay Wire To PCM Turn ignition off. With breakout box installed (PCM disconnected). Disconnect relay to be tested. To locate relay, see appropriate wiring diagram in the WIRING DIAGRAMS - 1.8L article in the ENGINE PERFORMANCE section. Measure resistance of circuit between relay test pin at breakout box and relay connector. (Scheme 15) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open wire between PCM and relay connector.

4) Check For Short In Relay Wire To PCM Turn ignition off. With breakout box installed and PCM disconnected, disconnect relay to be tested. Measure resistance between ground and breakout box test pin of relay being tested. If resistance is more than 10,000 ohms, go to next step. If resistance is 10,000 or less, repair short to ground in wire between PCM and relay connector.

5) Check Power To Suspect Relay Turn ignition off. Disconnect relay to be tested. Turn ignition on. Measure voltage at PWR terminal at relay connector. (Scheme 15) If voltage is more than 10 volts, replace relay. If voltage is 10 volts or less, repair PWR wire.

Identifying WAC Relay Connector Terminals. Scheme 15

Solenoid Controlled By Ground

Note. Enter this test only when Code 25, 26, 28, 29, 34, 41 or 46 is displayed during self-test procedures (KOEO or KOER). This test is intended to diagnose following solenoids and circuits: Canister Purge (CANP), EGR Control (EGRC), EGR Vent (EGRV), EGR Vacuum Regulator (EVR), Fuel Pressure Regulator Control (FPRC), High Speed Inlet Air Control (HSIA), Idle Air Control (IAC), injectors (INJ) or injector banks (BANK), and Variable Resonance Induction System Solenoids (VRIS).

CIRCUIT PIN IDENTIFICATION

1) Checking System Integrity Visually check all wiring, connectors and components for damage, shorting or looseness. If a fault is found, repair as necessary. If no fault is found, go to next step.

2) Solenoid Function Turn ignition off. Install breakout box, leaving PCM disconnected. Check function of appropriate solenoid. See SOLENOID FUNCTION TEST. If solenoid functions okay, test is complete. If no other problem or code is found, replace PCM. If solenoid does not function properly, go to next step.

3) Check Power To Solenoid Turn ignition off. Disconnect connector of solenoid to be tested. Turn ignition on. Measure voltage between connector ground and VPWR terminal at solenoid connector. (Scheme 16)-18. If voltage is less than battery voltage, go to CIRCUIT TEST VPWR. If VPWR circuit is okay, repair VPWR wire to solenoid. If voltage is battery voltage, go to next step.

4) Check For Open Solenoid Wire To PCM Turn ignition off. Ensure breakout box is installed and PCM is disconnected. Disconnect connector of solenoid to be tested. Measure resistance between solenoid test pin at breakout box and terminal at solenoid connector. (Scheme 16)-18. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open solenoid wire to PCM.

5) Check For Short In Solenoid Wire To PCM Turn ignition off. Ensure breakout box is installed and PCM is disconnected. Disconnect connector of solenoid to be tested. Measure resistance between ground and solenoid test pin at breakout box. If resistance is more than 10,000 ohms, replace solenoid. If resistance is less than 10,000 ohms, repair short to ground in solenoid wire.

Solenoid Performance Check

To further diagnose solenoid, ensure PCM and related circuits are capable of operating solenoid. Solenoids should operate under following conditions

1. BANK/INJ Solenoid should activate during cranking and while engine is running.
2. CANP With engine temperature more than 140°F (60°C), solenoid should activate during vehicle cruise or acceleration.
3. EGRC With engine temperature more than 140°F (60°C), solenoid should activate at normal driving (cruising).
4. EGRV With engine temperature more than 140°F (60°C), solenoid should activate during idle, deceleration or at wide open throttle.
5. FPRC Coolant temperature should be more than 190°F (88°C) and intake air temperature more than 68°F (20°C). Solenoid should activate with engine speed less than 1500 RPM and remain activated for 2 minutes after engine is started.
6. HSIA Solenoid should activate when engine speed is less than 5000 RPM.
7. IAC Solenoid should activate during engine cranking and running.
8. VRIS Solenoid should activate with engine at low speed.

Identifying Injector Connector Terminals. Scheme 16

Identifying Typical Solenoid Connector Terminals. Scheme 17

Identifying EVR/VRIS Solenoid Ports. Scheme 18

Switch Monitor Light

Note. Enter this test only when directed here by SWITCH MONITOR TEST. Switch monitor light is located on the Super Mecs adapter. This test is intended to diagnose SML circuit only.

1) Check For Open SML Wire Turn ignition off. Install breakout box, leaving PCM disconnected. Measure resistance between SML test pin (No. 38) at breakout box and SML terminal at data link connector. (Scheme 5) If resistance is less than 5 ohms, go to next step. If resistance is greater than 5 ohms, repair open SML wire.

2) Check For Short In SML Wire Turn ignition off. With breakout box installed and PCM disconnected, measure resistance between ground and SML test pin (No. 38) at breakout box. If resistance is 10,000 ohms or less, repair short in SML wire. If resistance is more than 10,000 ohms, check SML bulb, replace if necessary. If bulb is okay, replace PCM.

Switch To Ground

Note. Enter this test only when directed here by SWITCH MONITOR TEST. This test is intended to diagnose following switches and circuits: A/C Switch (ACS), Blower Motor Switch (BLMT), Clutch Cycling Pressure Switch (CCPS), Clutch Pedal Position (CPP) Switch, High Pressure Switch (HPS), Idle Switch (IDL), Park/Neutral Position Switch (PNP), Power Steering Pressure Switch (PSP), Rear Defroster Switch (DEF) and Wide Open Throttle Switch (WOT).

CIRCUIT PIN IDENTIFICATION

1) Check System Integrity Visually check all wiring, connectors and components for damage, shorting or looseness. If a fault is found, repair as necessary. If no fault is found, go to next step.

Note. If testing Idle Switch (IDL), ensure TPS is properly adjusted. See THROTTLE POSITION (TP) SENSOR in ADJUSTMENTS - 1.8L article.

2) Check Switch Signal To PCM Install breakout box. Connect PCM to breakout box. Measure voltage between ground and appropriate breakout box test pin of switch being tested. Check voltage with switch in open and closed positions. See SWITCH PERFORMANCE CHECK. Voltage should switch from less than one volt (switch closed) to more than 10 volts (switch open). If voltage is not as specified, go to next step. If voltage is as specified, switch is intermittent. See the TESTS W/O CODES - EEC (1.8L) article.

Note. For switch connector terminals (Scheme 19)- (Scheme 30).

3) Check For Open Switch Wire Ensure ignition is off. With breakout box installed, disconnect PCM connectors. Disconnect switch to be tested. Measure resistance between breakout box test pin of switch being tested and corresponding terminal at switch connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in wire tested.

4) Check For Short In Switch Wire Ensure ignition is off, breakout box is installed and PCM is disconnected. Disconnect switch to be tested. Measure resistance between ground and breakout box test pin of switch being tested. If resistance is less than 10,000 ohms, repair short to ground in wire between switch and PCM. If testing PSP or IDL switch, if resistance is 10,000 ohms or more, replace switch. On all other switches, if resistance is 10,000 ohms or more, go to next step.

Note. For switch connector terminals (Scheme 19)- (Scheme 30).

5) Check Ground At Suspect Switch Turn ignition off. Disconnect switch to be tested. Measure resistance between ground and GND terminal at connector of switch being tested (if applicable). If resistance is less than 5 ohms, replace switch. If resistance is at least 5 ohms, repair open in ground wire.

Switch Performance Check

Switch must be checked in ON (closed) and OFF (open) positions. Switch should function as follows

1. ACS Switch is closed when A/C is on and blower is operating.
2. BLMT Switch is closed with fan selector switch is in 2nd, 3rd or 4th position.
3. CCPS Switch is closed with A/C on and system pressure within normal operation range.
4. HPS Switch is closed with A/C on and system pressure exceeding normal operating range.
5. IDL Switch is open when throttle is depressed.
6. CPP/PNP CPP switch is closed when clutch pedal is depressed. PNP switch is closed when transaxle is in Neutral.
7. PSP Switch is closed when system pressure is high (turn steering wheel sharply with engine on).
8. WOT Switch is closed when throttle is wide open.

Switch Circuits (Type "A" Switch). Scheme 19

A/C Switch Connector Terminals. Scheme 20

CCP Switch Connector Terminals. Scheme 21

Defroster Switch Connector Terminals. Scheme 22

High Pressure Switch Connector Terminals. Scheme 23

Idle Switch Connector Terminals. Scheme 24

Switch Circuits (Type "B" Switch). Scheme 25

IDL & WOT Switch Connector Terminals (M/T). Scheme 26

Switch Circuits (Type "C" Switch). Scheme 27

CPP/PNP Switch Connector Terminals (M/T). Scheme 28

PNP Switch Connector Terminals. Scheme 29

CPP Switch Connector Terminals. Scheme 30

Self-Test Input

Note. Enter this test only when Super Star II tester displays STO LO or VOM displays zero volt.

CIRCUIT PIN IDENTIFICATION

1) Check System Integrity Visually check all wiring and connectors for evidence of damage, shorting or looseness. If fault is found, repair as necessary. If no fault is found, go to next step.

2) Check For Open STI Wire Turn ignition off. Install breakout box, leaving PCM disconnected. Measure resistance between STI test pin at breakout box and PCM STI terminal at Data Link Connector (DLC). (Scheme 5) If resistance is less than 5 ohms, go to next step. If resistance is greater than 5 ohms, repair open PCM STI wire between PCM and DLC.

3) Check For Short In PCM STI Wire Ensure ignition is off, breakout box is installed and PCM disconnected. Measure resistance between ground and STI test pin at breakout box. If resistance is more than 10,000 ohms, go to CIRCUIT TEST STO. If resistance is 10,000 ohms or less, repair short to ground in PCM STI wire.

Self-Test Output

Note. Enter this test only when instructed by CIRCUIT TEST STI.

CIRCUIT PIN IDENTIFICATION

1) Check System Integrity Visually check all wiring and connectors for evidence of damage, shorting or looseness. If a fault is found, repair as necessary. If no fault is found, go to next step.

2) Check For Open STO Wire Turn ignition off. Install breakout box, leaving PCM disconnected. Measure resistance between STO test pin at breakout box and PCM STO terminal at Data Link Connector (DLC). (Scheme 5) If resistance is less than 5 ohms, go to next step. If resistance is at least 5 ohms, repair open PCM STO wire.

3) Check For Short In STO Wire Ensure ignition is off, breakout box is installed and PCM disconnected. Measure resistance between ground and STO test pin at breakout box. If resistance is more than 10,000 ohms, go to CIRCUIT TEST PGC. If resistance is 10,000 ohms or less, repair short to ground in PCM STO wire.

Switch To Power

Note. Enter this test only when directed here from SWITCH MONITOR TEST. This test is intended to diagnose following switches and circuits: Brake On-Off (BOO) switch, Headlight (HDLT) switch, Rear Window Defrost (DEF) and Vehicle Start (VST) switch.

CIRCUIT PIN IDENTIFICATION

1) Check System Integrity Visually check all wiring, connectors and components for damage, shorting or looseness. If fault is found, repair as necessary. If no fault is found, go to next step.

2) Check Switch Signal To PCM Turn ignition off. Install breakout box, leaving PCM disconnected. Turn ignition on. Measure voltage at breakout box test pin of switch being tested. Check voltage with switch in ON (closed) and OFF (open) positions. See SWITCH PERFORMANCE CHECK. If voltage is as specified and no other problem or code is found, and CIRCUIT TEST SML has been performed, replace PCM. On headlight switch, if voltage is not as specified but headlights work, check for open wire. If headlights do not work, test headlight switch. See the STEERING COLUMN SWITCHES article in the ACCESSORIES/SAFETY EQUIPMENT section. On all other switches, if voltage is not as specified, go to next step.

Note. For switch connector terminals (Scheme 31)- (Scheme 33).

3) Check Power To Switch Turn ignition off. Disconnect connector of switch to be tested. Turn ignition on. Measure voltage at PWR terminal of switch. If voltage is about battery voltage, go to next step. If voltage is less than battery voltage, repair open PWR wire.

4) Check Switch Continuity Turn ignition off. Disconnect connector of switch to be tested. Measure resistance between switch terminals. Resistance should be less than 5 ohms with switch closed and more than 10,000 ohms with switch open. If resistance is not as specified, replace switch. If resistance is as specified and no other problem or code is found, replace PCM.

Check switch in ON and OFF positions. Install breakout box, leaving PCM disconnected. Turn ignition on. Measure voltage between breakout box test pin of switch being tested and ground. Switch should function as follows

1. BOO Depress brake pedal to close switch.
2. DEF Turn rear defroster on to close switch.
3. HDLT Turn headlight on to close switch.
4. VST Switch is closed when engine is cranking.

Defroster Switch Connector Terminals (3 & 5 Door). Scheme 31

Defroster Switch Connector Terminals (4 Door). Scheme 32

Brake On/Off Switch Connector Terminals. Scheme 33

Throttle Position (TP) Sensor (A/T)

Note. Enter this test only when a Code 12 is displayed during self-test procedures (KOEO or KOER) or when directed here from another circuit test. To prevent replacement of good components, check following non-EEC components for fault: idle speed or throttle stop adjustments, throttle shaft or linkage, and cruise control linkage.

CIRCUIT PIN IDENTIFICATION

1) Check System Integrity Visually check all wiring, connectors and components for evidence of damage, shorting or looseness. If fault is found, repair as necessary. If no fault is found, go to next step.

2) Check TP Sensor Signal Turn ignition off. Install breakout box. Install PCM to breakout box. Turn ignition on. Measure voltage at TP test pin at breakout box. Slowly depress accelerator pedal, and compare voltage to specifications shown in VOLTAGE & RESISTANCE SPECIFICATIONS (TP SENSOR) table. If voltage is as specified, and no other problem or code is found, replace PCM. If voltage is not as specified, go to next step.

3) Check VREF Turn ignition off. Disconnect TP sensor connector. Turn ignition on. Measure voltage at VREF terminal of TP sensor connector. (Scheme 34) If voltage is 4.5-5.5 volts, go to next step. On all models, if voltage is not 4.5-5.5 volts, go to CIRCUIT TEST VREF.

4) Check Wires To PCM Turn ignition off. With breakout box installed, disconnect PCM. Disconnect TP sensor connector. Measure and record resistances of TP wire and SIG RTN wire between test pins at breakout box and TP sensor connector. (Scheme 34) Measure and record resistance between ground and TP test pin at breakout box. If resistances are less than 5 ohms between test pins and TP sensor connector, and more than 10,000 ohms between ground and TP test pin, replace TP sensor. If resistance is not as specified, repair TP wire between TP sensor connector and PCM.

VOLTAGE & RESISTANCE SPECIFICATIONS

TP Sensor Circuit & Connector Terminals (A/T). Scheme 34

Volume Airflow Sensor

Note. Enter this test only when a Code 08 is displayed during self-test procedures (KOEO or KOER) or when directed here from another circuit test. To avoid unnecessary use of diagnostic time, check for unmetered air leaks between VAF sensor and throttle body. This test is intended to diagnose VAF and VMREF circuits only.

CIRCUIT PIN IDENTIFICATION (VAF)

1) Check System Integrity Visually check all wiring, connectors and components for evidence of damage, shorting or looseness. If fault is found, repair as necessary. If no fault is found, go to next step.

2) Check VAF Voltage Turn ignition off. Install breakout box. Connect PCM to breakout box. Access VAF measuring vane (air door). Turn ignition on. Measure voltage between VAF and SIG RTN test pins at breakout box while moving air door. If voltage is not as specified, go to next step. See VOLTAGE SPECIFICATIONS (VAF SENSOR) table. If voltage is as specified and no other problem or code is found, replace PCM.

3) Check VAF Signal From VAF Meter Turn ignition off. Access VAF measuring vane. Disconnect VAF meter connector. Connect a jumper wire between the VAF harness connector and VAF meter on VREF and SIG RTN wires. Turn ignition on. Measure voltage between VAF terminal at VAF meter and SIG RTN terminal at VAF meter connector while moving air door. (Scheme 35) Compare voltage to specifications shown in VOLTAGE SPECIFICATIONS (VAF SENSOR) table. If voltage is as specified, repair VAF wire to PCM. If voltage is not as specified, go to next step.

4) Check VREF At VAF Meter Turn ignition off. Disconnect VAF meter connector. Turn ignition on. Measure voltage between VREF and SIG RTN terminals at VAF meter connector. (Scheme 35) If voltage is 4.5-5.5 volts, replace VAF meter. If voltage is not 4.5-5.5 volts, go to CIRCUIT TEST VREF.

VOLTAGE SPECIFICATIONS

VAF Sensor Circuit & Connector Terminals. Scheme 35

Vehicle Power

Note. Enter this test only when directed here by other circuit tests. To prevent replacement of good components, check for faults in following non-EEC components: ignition switch, alternator, battery cables, ground straps and voltage regulator. This test is only intended to diagnose following circuits: VPWR and GND.

CIRCUIT PIN IDENTIFICATION

1) Check Circuit Integrity Visually check all wiring, connectors and components for evidence of damage, shorting or looseness. If fault is found, repair as necessary. If no fault is found, check battery voltage and charge condition. Service as necessary, and go to next step.

2) Check VPWR To PCM Turn ignition off. Install breakout box, leaving PCM disconnected. Turn ignition on. Measure voltage at VPWR test pin at breakout box. If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, go to step 4).

3) Check PCM Grounds Turn ignition off. With breakout box installed and PCM disconnected, measure resistance between ground and each GND test pin at breakout box. If all resistances are less than 5 ohms, VPWR circuit is okay. Return to circuit test that sent you here. If one or more resistance readings are 5 ohms or more, repair open in GND wire(s).

4) Check VPWR Wire From Power (Main) Relay To PCM Ensure ignition is off, breakout box is installed and PCM is disconnected. Remove power relay. Relay is located inside engine compartment fuse/relay box. Measure resistance between VPWR test pin at breakout box and VPWR at power relay connector. (Scheme 37) If voltage is less than 5 ohms, go to next step. If voltage is 5 ohms or more, repair open VPWR wire.

5) Check Ground At Power (Main) Relay Turn ignition off. Remove power (main) relay. Measure resistance between ground and GND terminal at power relay connector. (Scheme 37) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open power relay ground wire.

6) Check Voltage At Power (Main) Relay Turn ignition off. Measure voltage at BATT terminal at main relay connector. (Scheme 37) If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, check 30-amp FUEL INJECTOR fuse. Fuse is located in engine compartment fuse/relay box. Replace fuse if blown. If fuse is okay, repair wire between fuse and main relay.

7) Check Power To Power (Main) Relay With main relay removed, turn ignition on. Measure voltage at PWR terminal at main relay connector. (Scheme 37) If voltage is more than 10 volts, replace main relay. If voltage is 10 volts or less, check 15-amp ENGINE fuse. Fuse is located in instrument panel fuse block. Replace fuse if blown. If fuse is okay, repair PWR wire.

Power (Main) Relay Circuit. Scheme 36

Power (Main) Relay Connector Terminals. Scheme 37

Reference Voltage

Note. Perform this test when a check for VREF has failed in a sensor input circuit test. This test is only intended to diagnose following circuits: VREF and SIG RTN.

CIRCUIT PIN IDENTIFICATION

1) Check System Integrity Visually check all wiring, connectors and components for evidence of damage, shorting or looseness. If fault is found, repair as necessary. If no fault is found, go to next step.

2) Check VREF At PCM Turn ignition off. Install breakout box. Connect PCM to breakout box. Turn ignition on. Measure voltage between VREF and SIG RTN test pins at breakout box. If voltage is 4.5-5.5 volts, go to next step. If voltage is not 4.5-5.5 volts, go to CIRCUIT TEST VPWR. If VPWR circuit is okay, replace PCM.

3) Check For VREF At Sensor Turn ignition off. Disconnect BARO, EVP, VAF, MC-VAF and TP sensor connectors (if equipped). Turn ignition on. Measure voltage at VREF wire at each disconnected sensor connector. (Scheme 38) If all readings are 4.5-5.5 volts, VREF circuit is okay. Return to circuit test that sent you here. If any reading is 10-12 volts, repair short to power in VREF wire(s). If any reading is zero volts, go to next step.

4) Check For Open VREF Wires Turn ignition off. With breakout box installed, disconnect PCM. Disconnect BARO, EVP, VAF, MC-VAF and TP sensors. Measure resistance between VREF test pin at breakout box and VREF terminal of sensor connectors. (Scheme 38) If all resistance readings are less than 5 ohms, go to next step. If any reading is 5 ohms or more, repair open in VREF wire(s).

5) Check For Short In VREF Wires Turn ignition off. With breakout box installed, disconnect PCM. Measure resistance between ground and VREF test pin at breakout box. If all resistance readings are more than 10,000 ohms, repair SIG RTN wire to PCM. If any resistance reading is 10,000 ohms or less, repair short in wire in question.

VREF Terminals (A/T). Scheme 38

VREF Terminals (M/T). Scheme 39