Eec-Iv Theory/operation Ford Econoline E150

DESCRIPTION

The heart of the EEC-IV system is the Electronic Control Assembly (ECA). The ECA receives information from various sensors and switches. Based on information received and the operational program in the ECA's memory, the ECA generates output signals to control engine operation. In addition to controlling engine function, the ECA also controls gear shift and solenoid functions for the E4OD automatic transmission and Torque Converter Clutch Override (CCO) function on vehicles equipped with the A4LD automatic transmission. The calibration module for EEC-IV system is mounted inside the ECA. See ECA LOCATION table for location of ECA module.

The EEC-IV system controls 3 major areas of engine operation: air/fuel mixture, ignition timing, and emission control. Additionally, the system can control A/C compressor clutch operation and idle speed. The system provides self-diagnostic capabilities.

The EEC-IV ignition system is controlled by the ECA through Thick Film Integrated (TFI-IV) or Direct Ignition System (DIS) ignition modules. Ignition timing (advance or retard) and dwell are controlled with this system to improve ignition system performance.

Air/fuel mixture operation is accomplished by one of 3 different fuel injection systems depending on engine size and vehicle model. A Multi-Point Fuel Injection (MPFI) system is used.

Emission control components controlled by this system include EGR and canister purge. These systems are normally off, but are turned on when a mixture change signal allows operation of these units.

ECA LOCATION

ECA LOCATION

The engine control system consists of the ECA, sensors, switches, and actuators. In order for the ECA to perform properly, it must be kept constantly informed of engine operating conditions.

It is the task of the engine sensors to supply the ECA with specific information, in the form of electrical signals, required to determine engine operating conditions. The ECA sends out electrical signals to control air/fuel ratio, emission controls, idle speed and ignition timing.

The ECA controlled automatic transmission components consist of the Lock-Up Solenoid (LUS), Converter Clutch Override (CCO) and Shift Solenoid 3-4/4-3 (SS 3-4/4-3). Transmission input sensors consist of a temperature sensor, switches, and speed sensor. Individual component operation is as follows. All components may not be used on every vehicle

A/C Compressor Clutch Signal

When battery voltage is supplied to A/C compressor clutch, a signal is sent to the ECA (pin No. 10). The ECA uses this signal to increase engine idle speed to compensate for added load created by A/C compressor.

Air Charge Temperature (ACT) Sensor

The ACT sensor is threaded into a cylinder runner of the intake manifold or attached to air cleaner. It provides ECA with air/fuel mixture temperature information. The ECA uses this information to adjust fuel mixture, primarily during cold start enrichment periods.

Brake On/Off (BOO) Switch

The BOO switch signals the ECA that brakes are applied. The ECA adjust strategy for braking conditions.

EEC Power Relay

This relay is activated by ignition switch. Relay supplies battery voltage to ECA when ignition switch is in the "ON" position. Some relays incorporate a time delay feature which maintains power contact for 5-10 seconds after ignition is turned off.

EGR Valve Position (EVP) Sensor

This sensor is located on top of EGR valve. It inputs EGR valve position to the ECA.

Engine Coolant Temperature (ECT) Sensor (All Engines)

The ECT is mounted in the block or manifold to monitor engine coolant temperature. A signal is transmitted to the ECA, throughout the entire range of operating temperatures. This sensor is a thermistor type, its electrical resistance decreases as temperature increases. A cold engine will input a higher voltage signal to the ECA. Resistance does not change in direct proportion to temperature.

Knock Sensor

The knock sensor is a piezoelectric device designed to resonate at approximately the same frequency as engine knock. This unit senses and amplifies engine detonation (knock) and signals ECA to retard timing.

Manifold Absolute Pressure (MAP) Sensor

MAP sensor measures absolute pressure of mixture in intake manifold and sends a proportional signal to the ECA. It is mounted on right inner fender for 5.0L engine and left inner fender for all others. A vacuum hose is connected between the sensor and the intake manifold.

Neutral Drive Switch (NDS) & Neutral Gear Switch (NGS)

The NDS is used on Automatic Transmission (A/T) equipped vehicles to adjust idle speed due to increased load of engaged transaxle/transmission. Vehicles equipped with manual transaxle/transmission use a NGS switch to notify the ECA when transaxle/transmission is in gear.

Heated Oxygen (HEGO) Sensor

This sensor monitors oxygen content of exhaust gases. When it is at operating temperature, a voltage signal is produced which varies according to oxygen content of exhaust gases. The signal is transmitted to the ECA and is translated into a rich or lean mixture signal. A heating circuit in the sensor is used to bring the sensor to operating temperature.

Profile Ignition Pick-Up (PIP) (All Engines)

The PIP signal is generated by the ignition system. It informs the ECA of crankshaft position and engine speed. The PIP assembly is integral with distributor on all models. It has an armature with windows and metal tabs, that rotate past a stator assembly (Hall Effect switch). Ignition distributor does not have any mechanical or vacuum advance.

Power Steering Pressure Switch (PSPS)

The PSPS signals the ECA when power steering pressure exceeds 400-600 psi. The ECA uses this signal to raise engine rpm to compensate for power steering pump load when engine is at idle. Switch may be located on power steering rack or on power steering pump.

Self-Test Input (STI)

Self-Test Input (STI) is a circuit in the EEC system which is used to initiate the Self-Test procedures. The STI connector (pigtail) near the Self-Test connector is used to complete a circuit to activate this procedure. Self-Test functions are built into EEC-IV control module so system can display service codes for diagnosis of existing or intermittent problems.

Throttle Position (TP) Sensor

The rotary TP sensor is mounted on side of throttle body and connected directly to throttle plate shaft. The TP sensor senses throttle movement and position, and transmits a proportional electrical signal to ECA.

Vehicle Speed Sensor (VSS)

Sensor is transmission mounted, and sends a constant pulse signal to the ECA when the vehicle is in motion.

Wide Open Throttle A/C (WAC) Cut-Off

During Wide Open Throttle (WOT) operation, the WAC circuit interrupts power to the A/C compressor clutch. The A/C remains off for about 3 seconds after returning from WOT.

Canister Purge Solenoid (CANP)

This solenoid switches manifold vacuum to operate canister purge valve when a signal is received from ECA. Vacuum opens purge valve when solenoid is energized by ECA and fuel in charcoal emission canister is purged into intake system.

EGR Control (EGRC) Solenoid

Solenoid switches manifold vacuum to operate EGR valve on command from ECA. Vacuum opens the EGR valve when the solenoid is energized.

EGR Shut-Off (EGRSO) Solenoid

The EGR shut-off solenoid is an electrically-operated vacuum valve located between manifold vacuum source and EGR valve. A controlled vacuum bleed is located between solenoid and EGR valve. Vacuum bleed is a backpressure variable transducer. These 2 devices operate EGR valve. Solenoid switched vacuum is also supplied to canister purge valve.

EGR Vent (EGRV) Solenoid

Solenoid vents EGR control solenoid vacuum line. Valve is normally open. When energized, vacuum is supplied to EGR valve.

EGR Vacuum Regulator (EVR)

Controlled by a signal from the ECA. Regulates the amount of vacuum supplied to the EGR valve.

Fuel Injectors

On MPFI engines, each cylinder has a solenoid-operated injector which sprays fuel toward back of each intake valve. Each injector receives battery voltage through an ignition switch circuit. The ECA controlled ground circuit is used to complete the circuit and energize the injector. The ECA controls length of time each injector is "on" or energized. The "on" time governs the amount of fuel delivered.

Fuel Pump Relay

Fuel pump relay and ignition is activated by ECA when the ignition switch is in the "ON" or "START" positions. When ignition is turned on, the relay is activated to supply initial fuel line pressure to system.

Idle Speed Control By-Pass Air

The throttle air by-pass valve is a solenoid-operated valve controlled by ECA. The valve allows air to by-pass around throttle plates to control cold engine fast idle, no-touch start, dashpot, overtemperature idle boost, and engine load idle correction.

Self-Test Output (STO) (All Engines)

STO is a circuit in the ECA which transmits timed electrical pulse signals. These pulses correspond to self diagnostic service codes. They may be recorded using any of the following test equipment

1. Voltmeter (Digital or Analog)
2. The "Check Engine" Light or Malfunction Indicator Light (MIL) on the dash.
3. Ford Motor Co. Testers (STAR, SUPER STAR II, EEC-IV Monitor).
4. Aftermarket specialized testers.

Spark Output (SPOUT)

SPOUT information is transmitted from the ECA to the distributor. The SPOUT signal is the ECA generated ignition signal to the ignition module. A SPOUT connector is located in the SPOUT wire from the TFI module. If this connector is disconnected, ECA signal is interrupted and basic ignition function is controlled by the ignition module.

DIAGNOSTIC FORMATS

There are 2 diagnostic formats used to test and service the EEC-IV system: QUICK TEST and CIRCUIT TESTS. A DIAGNOSIS BY SYMPTOM TEST chart is available to identify specific problems and reference specific CIRCUIT TESTS, if no Key On Engine Off (KOEO) or Key On Engine Running (KOER) fault code is identified.

Always start with the QUICK TEST procedures before attempting any CIRCUIT TESTS. The QUICK TEST procedure is designed to allow the technician to identify problems and retrieve service codes. The CIRCUIT TESTS give procedures for testing circuits and checking sensors and actuators. If a vehicle passes the QUICK TEST procedures, and there are no driveability problems, the EEC-IV system is okay. Problem exists somewhere else besides the EEC-IV system. If an intermittent driveability problem exists, use the KOER "Wiggle" Test procedure to set a code or identify the problem.

RETRIEVING & CLEARING CODES

Service codes are retrieved from the EEC-IV system through the Self-Test connector by using various test equipment. The KOEO and KOER SELF-TESTS are used for this purpose. After these codes have been recorded or repaired, they may be cleared from the ECA memory.

To clear continuous memory codes, run the KOEO SELF-TEST, when service codes begin to appear on your test equipment or "Check Engine" light, disconnect the the jumper wire from the STI connector. If using a STAR tester, unlatch the center button. This will erase continuous memory codes from the processor's memory. If a problem has not been corrected, or the fault is still present, the code will be immediatly reset into the ECA memory.

TEST EQUIPMENT

The following equipment is recommended to diagnose and test EEC-IV system. Some equipment is REQUIRED to perform tests. DO NOT attempt to test this system without proper equipment. Damage to vehicle components may result if improper equipment is used.

1. The Self-Test Automatic Read-Out (STAR) Diagnostic Tester (Rotunda 007 00004) or SUPER STAR II (Rotunda 007-00028) is recommended but not required. It is specially built for the EEC-IV system and is used to display the 2-digit (numeric) service codes that are programmed into the control module. There are also a number of aftermarket scan tool testers available.
2. Analog Volt/Ohmmeter (VOM) with 0-20V DC range. This can be used as an alternate to diagnostic tester, to read codes only.
3. Digital Volt/Ohmmeter (DVOM) with minimum 10-megohm input impedance.
4. Breakout Box (Rotunda 014-00322). This is a jumper wire assembly which connects between the vehicle harness and the ECA. The breakout box is REQUIRED to perform certain tests on the system. Ford Motor Co. specifically states that back -probing will cause PERMANENT DAMAGE to the ECA 60-pin connector. The "test pin No." called out in CIRCUIT TESTS refers to Test Pin numbers on breakout box. Once the breakout box has been installed during a test sequence, it may remain connected for the remainder of that test unless otherwise specified. Aftermarket breakout boxes are available.
5. Vacuum gauge with 0-30 in. Hg range and resolution (units on scale) of 1 in. Hg.
6. Tachometer with 0-6000 RPM range, accuracy +/- 40 RPM, and a resolution of 20 RPM.
7. Vacuum pump with 0-30 in. Hg range.
8. Timing light.
9. Spark Tester (D81P-6666-A or ST-125). A modified side electrode spark plug IS NOT sufficient for these testing procedures.
10. Fuel Injection Pressure Gauge (T80L-9974-A).
11. 12-volt test light (non-powered type).
12. Jumper wire, about 15" long.
13. MAP/BP Tester. This unit plugs into MAP/BP sensor circuit and DVOM to check input and output signals. The MAP sensor produces a frequency signal which may be checked using a scope with a millivolt scale or a DVOM that measures frequency.

KOEO and KOER SELF-TEST Codes

All service codes are 2 digit numbers which are generated one digit at a time. These codes indicate a current fault in the system. They should be serviced in the order in which they appear. Use the appropriate code chart to find the correct CIRCUIT TEST. Codes are shown as voltage pulses (needle sweeps) on an analog Volt/Ohmmeter (VOM).

If a VOM is being used, pay careful attention to the length of the pauses in order to read the codes correctly. There will be a 1/2 second pause between the number of sweeps indicating a digit and a 2 second pause between each digit in a code. There will be a 4 second pause between each code. The KOEO SELF-TEST memory codes are separated from the Continuous Memory codes by a 6 second delay, a single 1/2 second sweep (Separator), and another 6 second delay. Always record the codes in the order received.

If a scan tool diagnostic tester is used, it will count the pulses and display them as a digital code. The STAR tester will add a zero (0) to single digit Separator (10) and Dynamic Response (10) codes. The Dynamic Response code is displayed in the KOER SELF-TEST. (Scheme 1)

If the "CHECK ENGINE" light is used, service codes will be displayed as flashes.

Separator Pulse

A single 1/2 second separator pulse is issued 6-9 seconds after last functional KOEO Self-Test code. Then 6-9 seconds after the single 1/2 second separator pulse, the continuous memory codes will be displayed.

Continuous Memory Codes

These codes are issued as a result of information stored by the ECA during continuous self test monitoring. These codes are displayed during the KOEO SELF-TEST after the separator pulse code. These codes should be used for diagnosis, ONLY when KOEO and KOER SELF-TEST results in a Code 11 and all QUICK TEST steps have been successfully completed. A Code 11 indicate vehicle has no recorded codes in the previous test sequence and is called a "Pass Code". There are a few exceptions which may be checked after the KOEO SELF-TEST codes have been repaired. These codes indicate a fault that has been recorded within the last 40 key starts. The fault may or may not be currently present.

Fast Codes

At the start of the KOEO testing and after the WOT request in the KOER test there is an output from the ECA known as "Fast Codes". These are short bursts of information that are used by the manufacturer during assembly. With most equipment these code bursts are not visible as the whole code sequence lasts less than 1/2 second. Ignore this fluctuation if noticed with your test equipment.

Scheme 1

The QUICK TEST diagnostic procedure is a functional test of the EEC-IV system. It consists of 7 basic test steps. These basic steps must be carefully followed in sequence, otherwise misdiagnosis, or replacement of non-faulty components may result.

1. VISUAL CHECK & VEHICLE PREPARATION
2. EQUIPMENT HOOK-UP
3. KEY ON ENGINE OFF (KOEO) SELF-TEST
4. COMPUTED TIMING CHECK
5. KEY ON ENGINE RUNNING (KOER) SELF-TEST
6. CONTINUOUS MONITOR MODE (WIGGLE TEST)
7. DIAGNOSIS BY SYMPTOM

After all tests, servicing, or repairs have been completed, repeat QUICK TEST to ensure all EEC-IV systems work properly.

KOEO & KOER SELF-TEST DESCRIPTION

The KOEO and KOER SELF-TESTS are intended to detect faults present at the time of testing, not intermittent faults. Intermittent faults are recorded and stored as Continuous Memory Codes, or may be detected by CONTINUOUS MONITOR MODE "WIGGLE" TEST, which is entered after the KOER SELF-TEST. A fault discovered during the "Wiggle" Test, may or may not set a code in the Continuous Memory, but the "Wiggle" Test is always circuit specific as directed in the CIRCUIT TESTS.

Note. Correct test results for system are dependent on the correct operation of several related non-EEC components and systems. All non-EEC problems in the engine, ignition or fuel system should be corrected before attempting to diagnose the EEC system.

VISUAL CHECK & VEHICLE PREPARATION

Before hooking up any equipment to diagnose the EEC system, make the following visual checks and perform the preparation procedures

1. Verify condition of air cleaner and air ducting.
2. Check all vacuum hoses for leaks, restrictions, and proper routing.
3. Check the EEC-IV system wiring harness electrical connections for corrosion, bent or broken pins, loose wires or terminals, and proper routing.
4. Check the ECA, sensors and actuators for physical damage.
5. Check engine coolant level.
6. Perform all necessary safety precautions to prevent personal injury or vehicle damage.
7. Set parking brake and place shift lever in "P" for automatic transmissions, and Neutral for manual transmissions. DO NOT move shift lever during test unless specifically directed to do so.
8. Turn off all lights and accessories. Ensure vehicle doors are closed when making voltage or resistance readings.
9. Start engine and idle until upper radiator hose is hot and pressurized, and throttle is off fast idle. Check for leaks around exhaust manifold, exhaust gas oxygen sensor, and vacuum hose connections.

Turn ignition off. Service items as required, then go to

EQUIPMENT HOOK-UP

SELF-TEST CONNECTOR LOCATION

SELF-TEST CONNECTOR LOCATIONS

Analog Volt/Ohmmeter (VOM)

1. Turn ignition switch to "OFF" position. Set VOM at 0-15V DC range and connect positive lead of VOM to positive battery terminal.
2. Connect negative VOM lead to pin No. 4 (STO) on Self-Test connector. (Scheme 2) Connect timing light, and go to KOEO SELF-TEST. KOEO SELF-TEST is activated by connecting jumper wire from Self-Test Input (STI) pigtail to pin No. 2 (Signal Return) on Self-Test connector with the ignition on.

Star Tester

Turn ignition switch to "OFF" position. Connect color coded adapter cable leads to diagnostic tester. Connect adapter cable's 2 service connectors to vehicle Self-Test and STI connectors. Connect timing light. Go to KOEO SELF-TEST.

"CHECK ENGINE" Light (MIL)

With ignition on, connect a jumper wire between STI and pin No. 2 of Self-Test connector. No additional special equipment hookup is required.

Overdrive Cancel Indicator Light (OCIL) & Transmission

Malfunction Indicator Light (TMIL) On 7.3L Diesel Engine Vehicles. With ignition on, connect a jumper wire between STI and pin No. 2 of Self-Test connector. No additional special equipment hookup is required.

Scheme 2

Test Procedure

1. Turn ignition switch to "OFF" position. Ensure all procedures of PREPARATION & EQUIPMENT HOOK-UP have been followed. Engine should be at normal operating temperature.
2. Turn ignition on. On 7.3L diesel engines, depress the throttle, it must remain depressed throughout the entire KOEO test. On 4.9L engines with manual transmissions, the clutch must be depressed throughout the entire test. If using an analog VOM or the "Check Engine" (MIL) light, connect a jumper wire from Self-Test Input (STI) pigtail to pin No. 2 (Signal Return) on Self-Test connector, this will activate the KOEO Self-Test. If Star Tester is being used latch center button in down position at this time.
3. The ECA will run through a test cycle, opening and closing various solenoids and switches. After the completion of the test cycle the codes will appear. Record all codes. NOTE: DO NOT depress the throttle during the KOEO SELF-TEST. Ensure ignition switch is in the "ON" position before jumping STI connector to pin No. 2 of the Self-Test connector.
4. The first set of codes to appear are the KOEO SELF-TEST codes, they will be repeated twice, followed by the Separator Pulse signal and then the CONTINUOUS MEMORY codes. These codes will also be repeated twice.
5. A KOEO Code 11 indicates the system has passed the self-test. A Code 11 must be present before continuing. Disregard any Continuous Memory Codes at this time. Service KOEO codes in the order they appear. Refer to the KOEO SELF-TEST CODES table to find the appropriate CIRCUIT TEST. After each repair, repeat KOEO SELF-TEST until a Code 11 is displayed.
6. If no KOEO codes are displayed, a Code 11 (pass code) and a Code 10 (separator pulse) are present, record the Continuous Memory Codes. Service only the KOEO CONTINUOUS MEMORY CODE EXCEPTIONS at this time. All other Continuous Memory Codes will be serviced after a Code 11 is displayed during the KOER SELF-TEST.

KOEO CONTINUOUS MEMORY CODE EXCEPTIONS

No Starts (Except Diesel)

If engine does not start, go to CIRCUIT TEST A1, step 1). Proceed through this test procedure until engine is running and then repeat KOEO SELF-TEST. If engine stalls or is unable to complete KOEO SELF-TEST, DIAGNOSIS BY SYMPTOM table may be used until engine is able to complete KOEO SELF-TEST.

No Codes Displayed Or Codes Displayed Not Listed

The KOEO SELF-TEST did not activate or non-system codes were displayed. Repeat KOEO SELF-TEST to verify condition. If condition still exists go to CIRCUIT TEST D14, step 1).

COMPUTED TIMING CHECK

1. Turn key off and wait 10 seconds. Start engine. Activate KOER SELF-TEST. After the last service code has been displayed, the timing will remain fixed for 2 minutes, unless KOER SELF-TEST is deactivated.
2. Correct Self-Test timing equals base ignition timing (10 degrees BTDC on most engines, see emission decal) plus 17-23 degrees BTDC. If timing is not 27-33 degrees BTDC, go to CIRCUIT TEST D13. If timing is 27-33 degrees BTDC, proceed with KOER SELF-TEST.

This test checks engine sensors under actual operating conditions and at operating temperature. The ECA operates and tests actuators and sensors during this test. A number of special test procedures may be requested by the ECA during this test, depending on vehicle equipment. These tests allow the ECA to test the following sensors.

Engine ID Codes

The first code displayed during the KOER SELF-TEST is an engine identification code. They indicate the number of cylinders in the engine. An engine ID Code of 2 (20), 3 (30), or 4 (40) indicates 4, 6, or 8 cylinder engines, repectively.

Dynamic Response or Wide Open Throttle (WOT) Check

Allows the ECA to check the TP and MAP sensors. This test is accomplished by a brief opening of the throttle to the full open position. It is also called the "Goose" test. It is requested by a single pulse or Code 10 approximately 6-20 seconds after the engine identification codes are displayed.

1. Deactivate Self-Test by disconnecting STI jumper wire. Start and run engine at 2000 RPM for 2 minutes to warm up HEGO sensor. Turn engine off and wait 10 seconds
2. Start engine. Insert jumper to activate Self-Test. The engine ID code will be displayed. On vehicles equipped with Brake On/Off switch (BOO), the brake pedal MUST be depressed and released AFTER the ID code (within 1-2 seconds). On vehicles equipped with Power Steering Pressure Switch (PSPS), the steering wheel MUST be turned one-half turn and released AFTER the ID code. On vehicles equipped with an Overdrive Cancel Switch (OCS) the switch must be cycled AFTER the ID code.
3. If a Dynamic Response request code occurs, briefly depress accelerator pedal to Wide Open Throttle (WOT). A Dynamic Response request code is a Code 1 or 10 displayed after the Engine ID code and before the Engine Running codes. DO NOT depress throttle during test unless a Dynamic Response request code occurs. The KOER SELF-TEST service codes will then be displayed. Observe and record all codes.

CONTINUOUS MONITOR MODE (WIGGLE TEST)

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

KOEO "Wiggle" Test Procedure

Connect test equipment. (Scheme 2) Turn ignition on and activate Self-Test with jumper lead or diagnostic tester. Wait 10 seconds, deactivate, and then reactivate Self-Test. You are now in "Wiggle" test mode. Tap, move, and wiggle the suspected sensor and/or harness area. If a fault is detected, a service code may be stored in memory and indicated at the diagnostic tester or scan tool. Record or retrieve code and perform test indicated in CONTINUOUS SELF-TEST CODES table.

KOER "Wiggle" Test Procedure

Connect test equipment. (Scheme 2) Turn ignition off and wait 10 seconds. Start engine. Activate Self-Test with jumper lead or diagnostic tester. Wait 10 seconds, deactivate, and then reactivate Self-Test. DO NOT turn engine off. You are now in engine running "Wiggle" test mode. Tap, move, and wiggle the suspected sensor and/or harness area. If a fault is detected, a service code may be stored in memory and indicated at the diagnostic tester or scan tool. Record or retrieve code and perform test indicated in CONTINUOUS SELF-TEST CODES table.

DIAGNOSIS BY SYMPTOM

A pass code (11-10-11), indicates there are no active codes in the KOEO or KOER SELF-TEST. If driveability symptoms still exist and the EEC system is still suspect, use the DIAGNOSIS BY SYMPTOM TEST for referral to the appropriate CIRCUIT TEST.

DIAGNOSTIC AIDS

A number of additional diagnostic test features are available to aid in diagnosis of driveability problems.

Output State Check

The Output State Check is used as an aid in servicing output actuators associated with the EEC-IV system. It allows you to energize and de-energize most of the system output actuators on command. This mode is entered from the KOEO SELF-TEST after all codes have been received. At this time, leave SELF-TEST activated and depress throttle to initiate the test sequence. Each time throttle is depressed and released, the output actuators will change state (go from on to off, or off to on).

Failure Mode Effects Management (FMEM), Code 98

The FMEM mode allows system operation when one or more sensors fail or transmit signals which are out of their normal operating range. The ECA will substitute a mid-range signal for the defective sensor and continue to monitor the sensor. If the faulty sensor signals return to within the normal operating range the ECA will use those signals. A Code 98 will be displayed when the FMEM mode is in effect.

ECA PIN VOLTAGE & RESISTANCE CHECKS

The ECA pin voltage chart may be helpful when diagnosing hard-to-find problems. It must be used with a EEC-IV breakout box and a high impedance DVOM. The voltages and resistances shown are typical component values. Actual measured values may differ slightly from those shown. Always check wiring diagrams for actual pin callouts as some models may vary slightly, depending on equipment. Components shown may not be on all vehicles. The engine should be at normal operating temperature and run at 2000 RPM for about 2 minutes and returned to idle. Always refer to the appropriate CIRCUIT TEST to diagnose a suspected faulty component. The following criteria should be noted when checking the appropriate components.

Engine Coolant Temperature (ECT) Sensor

Coolant temperature must be 180-240°F (82-116°C) before measurements are taken.

Distributor Position (PIP)

Applies to vehicles equipped with TFI-IV ignition systems only.

If vehicle is not moving speed sensor output to the ECA will be zero. Vehicle must be moving to provide input.

Knock Sensor (KS)

Output voltage is a variable signal of 300 mV or greater, depending on severity of engine knock. Background noise will not affect output.

ECA SENSOR & ACTUATOR RESISTANCE (1)

PIN VOLTAGE REFERENCE CHART (1)

EEC-IV ABBREVIATIONS

1. A/C: Air Conditioning
2. ACCS: A/C Cycling Switch
3. ACC: A/C Clutch Compressor
4. ACT: Air Charge Temperature sensor
5. ACV: Thermactor Air Control Valve
6. AXOD: Automatic Transaxle Overdrive
7. BOO: Brake On/Off switch
8. BP: Barometric Pressure sensor
9. CANP: Canister Purge solenoid
10. CCO: Converter Clutch Override
11. CFI: Central Fuel Injection
12. CID: Cylinder Identification sensor
13. DIS: Direct Ignition System
14. DVOM: Digital Volt/Ohm Meter (see VOM)
15. ECA: Electronic Control Assembly, processor, computer
16. ECT: Engine Coolant Temperature sensor
17. EDF: Electric Drive Fan relay assembly
18. EEC: Electronic Engine Control
19. EGO: Exhaust Gas Oxygen sensor (see HEGO)
20. EGR: Exhaust Gas Recirculation system
21. EGRC: EGR Control solenoid or system
22. EGRV: EGR Vent solenoid or system
23. EVP: EGR Position sensor
24. EVR: EGR Valve Regulator
25. FI: Fuel Injector or Fuel Injection
26. FIPL: Fuel Injection Pump Lever
27. FP: Fuel Pump
28. FPM: Fuel Pump Monitor
29. FWD: Front Wheel Drive
30. GND or GRND: Ground
31. HEDF: High Speed Electro Drive Fan relay or circuit
32. HEGO: Heated EGO sensor
33. HEGOG: HEGO Ground circuit
34. HO: High Output
35. HSC: High Swirl Combustion, engine type
36. IDM: Ignition Diagnostic Module
37. IGN: Ignition system or circuit
38. INJ: Injector or Injection
39. ISC: Idle Speed Control
40. ITS: Idle Tracking Switch
41. KAM: Keep Alive Memory
42. KAPWR: Keep Alive Power
43. KOEO: Key On Engine Off
44. KOER: Key On Engine Running
45. KS: Knock Sensor
46. L: Liter(s)
47. LOS: Limited Operation Strategy, computer function
48. LUS: Lock-Up Solenoid
49. MAF: Mass Air Flow sensor, meter or circuit
50. MAP: Manifold Absolute Pressure sensor
51. MA SEFI: Mass Air Sequential Fuel Injection system
52. MCU: Microprocessor Control Unit
53. MIL: Malfunction Indicator Light
54. MLP: Manual Lever Position sensor
55. MPFI: Multi Point Fuel Injection
56. NDS: Neutral Drive Switch
57. NGS: Neutral Gear Switch
58. NPS: Neutral Pressure Switch
59. OCC: Output Circuit Check
60. OHC: Overhead Camshaft, engine type
61. OSC: Output State Check
62. PFE: Pressure Feedback EGR sensor or circuit
63. PIP: Profile Ignition Pickup
64. PSPS: Power Steering Pressure Switch
65. PWR GND: Power Ground circuit
66. RWD: Rear Wheel Drive
67. SEFI: Sequential Fuel Injection (see MA SEFI)
68. SIG RTN: Signal Return circuit
69. SIL: Shift Indicator Light
70. SPOUT: Spark Output Signal, from ECA
71. SS 3/4-4/3: Shift Solenoid circuit
72. STAR: Self Test Automatic Readout, test equipment
73. STI: Self Test Input circuit
74. STO: Self Test Output circuit
75. TAB/TAD: Thermactor Air Bypass/Thermactor Air Diverter Tandem solenoid valves operated by separate circuits.
76. TFI: Thick Film Ignition system
77. TGS: Top Gear Switch (cancels SIL operation in top gear)
78. THS: Transmission Hydraulic Switch
79. TOT: Transmission Over Temperature sensor
80. TP or TPS: Throttle Position Sensor
81. TTS: Transmission Temperature Switch
82. VAF: Vane Air Flow sensor or circuit
83. VAT: Vane Air Temperature
84. VBATT: Vehicle Battery Voltage
85. VM: Vane Meter
86. VOM: Analog Volt/Ohm Meter (see DVOM)
87. VPWR: Vehicle Power supply voltage (regulated 10-14 volts)
88. VREF: Voltage Reference (ECA supplied reference voltage, 4-6 volts)
89. VSC: Vehicle Speed Control sensor or signal
90. VSS: Vehicle Speed Sensor or signal
91. WAC: WOT A/C Cut-off switch or circuit
92. WOT: Wide Open Throttle

2.9L EEC-IV Wiring Diagram (Bronco II & Ranger). Scheme 3

3.0L EEC-IV Wiring Diagram (Aerostar). Scheme 4

4.9L EEC-IV Wiring Diagram (Bronco & "F" Series). Scheme 5

4.9L EEC-IV Wiring Diagram ("E" Series). Scheme 6

5.0L, 5.8L & 7.5L EEC-IV Wiring Diagram (Bronco & "F" Series). Scheme 7

5.0L, 5.8L & 7.5L EEC-IV Wiring Diagram ("E" Series). Scheme 8

7.3L Diesel EEC-IV Wiring Diagram ("F" Series). Scheme 9

7.3L Diesel EEC-IV Wiring Diagram ("E" Series). Scheme 10

See also:
• EQUIPMENT HOOK-UP