Engine Controls - Tests W/codes - Eec 2.5L: Diagnosis Ford Probe II

ENTERING SELF-DIAGNOSTICS

Diagnostic Trouble Codes (DTCs) can be retrieved using one of the following methods.

1. Using an analog Volt-Ohmmeter (VOM).
2. Using Malfunction Indicator Light (MIL).
3. Using Superstar II (007-0041B) scan tester.
4. Using New Generation Star (007-00500) scan tester.

Codes are accessed from PCM using Data Link Connector (DLC). see scheme 1and see scheme 2. Procedure to retrieve codes varies with each method. Follow QUICK TEST procedure for specific method being used to retrieve codes. If no code or only intermittent fault is found after performing QUICK TEST, proceed to SWITCH MONITOR TEST.

Note. Before hooking up equipment to diagnose EEC system, prepare and visually inspect vehicle. See VISUAL CHECK & VEHICLE PREPARATION.

READING SELF-DIAGNOSTIC CODES

Note. Accuracy of self-diagnostics depends on correct operation of non-EEC components and systems. Correct all non-EEC problems in engine, ignition or fuel system attempting to diagnose EEC system.

Note. EEC system will not display a PASS code.

PCM outputs self-diagnostic 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 appropriate CODE REFERENCE table to find correct CIRCUIT TEST.

QUICK TEST

Note. Reading codes using MIL pulses is similar to reading codes using VOM needle sweeps. See ANALOG VOM OR MIL.

SWITCH MONITOR TEST

Perform this test if no code is present after performing KOEO and KOER self-tests. Switch monitor tests determine if electrical signals to PCM from input devices are correct. In this procedure, each device is tested individually. Perform test using Super Star II tester or Analog Volt-Ohmmeter (VOM).

TEST EQUIPMENT

Following equipment is recommended for testing EEC system. DO NOT attempt to test this system without proper equipment. Damage to vehicle components may result if improper equipment is used.

1. Digital Volt-Ohmmeter (DVOM) with minimum 10-megohm input impedance.
2. A breakout box and breakout box adapter (007-00057 or T92C -6000) is required to perform certain tests on system. Test pin number mentioned in circuit tests refers to test pin number on breakout box. Breakout box Adapter (T92C-6000-AH) has an A/B position selector switch. Ensure switch is in correct position for each test step. If no switch position is given, switch can be in either position. Once breakout box has been installed during a test sequence, it may stay connected for remainder of that test, unless stated otherwise. Aftermarket breakout boxes are also available.
3. Vacuum gauge with 0-30 in. Hg range and resolution (units on scale) of 1 in. Hg.
4. Tachometer with 0-6000 RPM range, +/- 40 RPM accuracy, and a resolution of 20 RPM.
5. Vacuum pump with 0-30 in. Hg range.
6. Timing light.
7. Spark Tester (D81P-6666-A or ST-125) is required. A modified side electrode spark plug is not sufficient for these procedures.
8. Fuel Injection Pressure Gauge (T80L-9974-A).
9. 12-volt test light (non-powered type).
10. Jumper wire about 15" long.

Note. Following circuit tests and illustrations are provided courtesy of Ford Motor Co. Complete EEC system wiring diagrams may be found in WIRING DIAGRAMS .

CIRCUIT TEST BARO - 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 for fault in following non-EEC items: atmospheric barometer reading (unusually high or low), vacuum lines (blocked) and basic mechanical engine components. This test is intended to diagnose BARO circuit only.

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.

Identifying Distributor Connector Terminals (2.5L - CID). Scheme 96

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 CID circuit only.

Note. CID sensor may also be known as CMP sensor and is part of Crankshaft Position (CKP) sensor 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 CID Signal Turn ignition off. Install breakout box. Connect PCM to breakout box. Measure voltage at CID 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 CID Wire Ensure ignition is off. With breakout box installed, disconnect PCM connectors. Measure resistance of CID wire between ground and CID 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 CID circuit wire.

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

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

Identifying Distributor Connector Terminals (CKP1 - 2.5L). Scheme 97

Note. Enter this test only when Code 04 is displayed during self-test procedures (KOEO or KOER) or when directed here from another circuit test. This test is intended to diagnose CKP1 circuit only.

Note. Probe has 2 crankshaft position sensors.

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 CKP1 Signal Turn ignition off. Install breakout box. Connect PCM to breakout box. Measure voltage at CKP1 test pin at breakout box while bumping starter. If voltage does not fluctuate between zero and 5 volts, go to next step. If voltage fluctuates between zero and 5 volts, CKP1 circuit is okay. If sent to this test by a specific code, replace PCM.

3) Check VPWR To Distributor Turn ignition off. Disconnect distributor connector. Turn ignition on. Measure voltage at 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.

4) Check Distributor Ground Ensure ignition is off and distributor is disconnected. Measure resistance between distributor connector 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.

5) Check For Open CKP1 Wire Ensure ignition is off and distributor is disconnected. With breakout box installed, disconnect PCM connectors. Measure resistance of CKP1 wire between CKP1 test pin at breakout box and CKP1 terminal at distributor connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open CKP1 wire.

6) Check For Short In CKP1 Wire Ensure ignition is off and distributor is disconnected. With breakout box installed and PCM disconnected, measure resistance of CKP1 wire between ground and CKP1 test pin at breakout box. If resistance is more than 10,000 ohms, replace distributor. If resistance is 10,000 ohms or less, repair short to ground in CKP1 wire.

Identifying CKP2 Sensor Connector Terminals (CKP2 - 2.5L). Scheme 98

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 CKP2 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 CKP2 Sensor Turn ignition off. Install breakout box, leaving PCM disconnected. With CKP2 sensor temperature at 68°F (20°C), measure resistance between test pins CKP2 and CKP RTN at breakout box. If resistance is 520-580 ohms, CKP2 circuit is okay. If no other problem or code is found, replace PCM. If resistance is not 520-580 ohms, go to next step.

3) Check For Open CKP2 Sensor Wires Ensure breakout box is installed and PCM is disconnected. Disconnect CKP2 sensor connector. Measure resistance of CKP2 and CKP RTN wires between appropriate test pins at breakout box and corresponding terminals at CKP2 sensor connector. If both resistance readings are less than 5 ohms, go to next step. If either reading is 5 ohms or more, repair open wire(s) between CKP2 sensor connector and PCM.

4) Check For Short In CKP2 Sensor Wires Ensure breakout box is installed and PCM is disconnected. With CKP2 sensor disconnected, measure resistance between ground and CKP2 and CKP RTN test pins at breakout box. If both resistance readings are more than 10,000 ohms, go to next step. If either reading is 10,000 ohms or less, repair short to ground in wire(s) between CKP2 sensor connector and PCM.

5) Check Ground Circuit Turn ignition off. Disconnect CKP2 sensor. Measure resistance between ground and GND terminal at CKP2 sensor connector. If resistance is less than 5 ohms, replace CKP2 sensor. If resistance is 5 ohms or more, repair open GND circuit.

ECT Sensor Circuit & Connector Terminal ID (2.5L ECT). Scheme 99

ECT Sensor Circuit & Connector Terminal ID (2.5L ECT). Scheme 100

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 using Rotunda Digital Thermometer (055-00100). Turn ignition off. Install breakout box, leaving PCM disconnected. Measure resistance between ETC and GND 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. Measure and record resistance between ground and ECT test pin at breakout box. If resistance between ECT test pin at breakout box and ECT terminal at ECT sensor connector is less than 5 ohms and resistance between ground and ECT test pin at breakout box is greater than 10,000 ohms. If resistance is not as specified, repair ECT wire between ECT sensor connector and PCM.

4) Check Ground Circuit Ensure ignition is off and ECT sensor is disconnected. Measure resistance between ground and GND terminal at ECT sensor connector. If resistance is less than 5 ohms, replace ECT sensor. If resistance is 5 ohms or more, repair GND wire between ECT sensor connector and PCM.

EVP Sensor Ckt. & Conn. Terminal ID - 1 Of 2 (EVP - 2.5L). Scheme 101

EVP Sensor Ckt. & Conn. Terminal ID - 2 Of 2 (EVP - 2.5L). Scheme 102

Note. Enter this test only when a Code 16 is displayed during self-test procedures (KOEO or KOER) or when directed here from another circuit test. This test is intended to diagnose EVP circuit only.

CIRCUIT PIN IDENTIFICATION

1) Check System Integrity Visually check all wiring, connectors and components for evidence of damage, shorting or looseness. Check vacuum hoses between EGR valve and intake manifold. Install a vacuum gauge in EGR vacuum line and drive vehicle while observing vacuum gauge. Vacuum gauge should read about 10 in. Hg at steady cruise and no vacuum at idle or deceleration. If vacuum readings are okay, go to next step. If vacuum readings are abnormal, repair EGR system. See appropriate SYSTEM/COMPONENT TESTS - EEC (2.5L) article in the ENGINE PERFORMANCE section.

2) Check EVP Signal To PCM Turn ignition off. Install breakout box. Connect PCM to breakout box. Install vacuum tester to EGR vacuum port. Turn ignition on. Measure voltage between ground and EVP test pin at breakout box. Turn ignition on. Slowly apply vacuum to EGR valve. Compare voltmeter readings to specifications. See VOLTAGE SPECIFICATIONS (EVP SENSOR) table. If voltage is as specified, EVP circuit is okay. If no other problem or code is found, replace PCM. If voltage is not as specified, go to next step.

VOLTAGE SPECIFICATIONS

3) Check VREF At EVP Sensor Turn ignition off. Disconnect EVP sensor connector. Turn ignition on. Measure voltage at VREF terminal at EVP sensor connector. 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 VREF.

4) Check Ground At EVP Sensor Ensure ignition is off and EVP sensor is disconnected. Measure resistance between ground and GND terminal at EVP sensor connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair EVP sensor ground wire.

5) Check For Open EVP Wire Ensure ignition is off and EVP sensor is disconnected. With breakout box installed, disconnect PCM connectors. Measure resistance between EVP test pin at breakout box and EVP terminal at EVP sensor connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open EVP wire.

6) Check For Short In EVP Wire Ensure ignition is off and EVP sensor is disconnected. With breakout box installed and PCM disconnected, measure resistance between ground and EVP 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 EVP wire.

7) Check EVP Wire For Short To VREF Turn ignition off. Install breakout box. Disconnect EVP sensor. Measure resistance between breakout box test pins EVP and VREF. If resistance is greater than 10,000 ohms, replace EVP sensor. If resistance is less than 10,000 ohms, repair EVP and VREF wires.

Identifying HO2S Circuit & Connector Terminals (HO2S). Scheme 103

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 or 17 indicates left HO2S malfunction. Code 23 or 24 indicates right HO2S malfunction. Code 15 or 23 indicates continuous output voltage of less than .55 volt (lean condition). Code 17 or 24 indicates HO2S feedback system does not change (rich condition) and may indicate condition other than HO2S circuit malfunction.

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

3) Check HO2S Ground Turn ignition off. Disconnect HO2S sensor connector. Measure resistance ground and GND terminal at HO2S connector (harness side). If resistance is less than 5 ohms, go to step 5). If resistance is 5 ohms or more, repair sensor GND wire.

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. 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. 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 Turn ignition on. Measure voltage at PWR terminal at HO2S connector. 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.

IAT Sensor Circuit & Connector Terminal ID (IAT - 2.5L). Scheme 104

IAT Sensor Circuit & Connector Terminal ID (IAT - 2.5L). Scheme 105

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 Measuring Core-Volume Vane Airflow (MC-VAF) meter. Monitor temperature at IAT sensor using Rotunda Digital Thermometer (055-00100). Measure resistance between IAT and GND 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 MC-VAF sensor connector. Measure resistance between IAT test pin at breakout box and IAT terminal at VAF or MC-VAF sensor connector. 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 MC-VAF sensor connector. Measure resistance between ground and IAT test pin at breakout box. If resistance is more than 10,000 ohms.

5) Check IAT Sensor Ground Ensure ignition is off. Measure resistance of GND wire between ground and IAT terminal at MC-VAF sensor connector. If resistance is less than 5 ohms, replace MC-VAF sensor. If resistance is 5 ohms or more, repair IAT GND wire.

KS Circuit & Connector Terminals (KS - 2.5L) ID. Scheme 106

Note. Enter this test only when a Code 05 is displayed during self-test procedures (KOEO or KOER) or when directed here from another circuit test. This test is intended to diagnose KS 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 Signal From PCM Turn ignition off. Install breakout box. Connect PCM to breakout box. Turn ignition on. Measure voltage between ground and KS test pin at breakout box. If voltage is about 2.4 volts, go to next step. If voltage is not about 2.4 volts, go to CIRCUIT TEST VPWR. If VPWR circuit is okay and no other problem or code is found, replace PCM.

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

4) Check For Short In KS Wire Ensure ignition is off, breakout box is installed and PCM is disconnected. With KS connector disconnected, measure resistance between ground and KS test pin at breakout box. If resistance is more than 10,000 ohms, go to next step. If resistance is less than 10,000 ohms, repair short to ground in KS wire.

5) Check KS Ground Turn ignition off. With KS connector disconnected, measure resistance of GND wire between ground and KS connector. If resistance is less than 5 ohms, replace KS. If resistance is at least 5 ohms, repair open GND wire.

MC-VAF Sensor Circuit & Conn. Terminal ID (MC-VAF - 2.5L). Scheme 107

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 MC-VAF meter and throttle body. This test is intended to diagnose MC-VAF 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 MC-VAF Sensor Input Voltage To PCM Turn ignition off. Install breakout box. Connect PCM to breakout box. Access MC-VAF sensor in air cleaner. Turn ignition on. Measure voltage between MC-VAF and GND test pins at breakout box while moving MC-VAF measuring core. Compare voltage readings with VOLTAGE SPECIFICATIONS (MC-VAF METER) table. If voltage is as specified, MC-VAF circuit is okay. Replace PCM. If voltage is not as specified, go to next step.

VOLTAGE SPECIFICATIONS

3) Check VREF At MC-VAF Sensor Turn ignition off. Disconnect MC-VAF sensor connector. Turn ignition on. Measure voltage at VREF terminal at MC-VAF sensor connector. 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 VREF.

4) Check For An Open MC-VAF Wire Turn ignition off. With breakout box installed, disconnect PCM. Ensure MC-VAF sensor is disconnected. Measure resistance at MC-VAF test pin at breakout box and MC-VAF terminal at MC-VAF sensor connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open MC-VAF wire.

5) Check For Short In MC-VAF Wire Turn ignition off. Ensure breakout box is installed and PCM and MC-VAF sensor are disconnected. Measure resistance between ground and MC-VAF 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 MC-VAF wire.

6) Check MC-VAF Sensor Ground Turn ignition off. Ensure MC-VAF is disconnected. Measure resistance between GND test pin at breakout box and GND terminal at MC-VAF sensor connector. If resistance is less than 5 ohms, replace MC-VAF sensor. If resistance is 5 ohms or more, repair open GND wire.

Instrument Cluster Connector Terminal ID (MIL). Scheme 108

Instrument Cluster Connector Terminal ID (MIL). Scheme 109

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

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 MIL test pin (No. 51) 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 MIL test pin (No. 31) at breakout box and MIL terminal at instrument cluster connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in 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 MIL test pin (No. 51) 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.

CIRCUIT TEST PGC - 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.

ACR Relay Connector Terminal ID (ROC - 2.5L). Scheme 110

FPR Relay Connector Terminal ID (ROC - 2.5L). Scheme 111

HCFAN Relay Connector Terminal ID (ROC - 2.5L). Scheme 112

HFAN Relay Connector Terminal ID (ROC - 2.5L). Scheme 113

LCFAN Relay Connector Terminal ID (ROC - 2.5L). Scheme 114

LFAN Relay Connector Terminal ID (ROC - 2.5L). Scheme 115

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 following relays and circuits: A/C Relay (ACR), Fuel Pump Relay (FPR), High Condenser Fan Relay (HCFAN), High Cooling Fan Relay (HFAN), Low Condenser Fan Relay (LCFAN), Low Cooling Fan Relay (LFAN) and 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). Locate relay to be tested. Turn ignition on. Feel and/or listen to relay while grounding appropriate relay test pin atbreakout 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. Measure resistance between breakout box test pin of relay being tested and relay terminal to PCM at relay connector. 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.

Note. When testing HFAN or HCFAN relays, both HFAN and HCFAN relays must be disconnected.

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. If voltage is more than 10 volts, replace relay. If voltage is 10 volts or less, repair PWR wire.

Injector Connector Terminal ID (SCG1). Scheme 116

Injector Connector Terminal ID (SCG1). Scheme 117

Typical Solenoid Connector Terminal ID (SCG2). Scheme 118

EVR/VRIS Solenoid Port ID (SCG3). Scheme 119

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 ACTIVATION 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. 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. 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 Function Test

To further diagnose solenoid, ensure PCM and related circuits are capable of operating solenoid. When test procedure requires simulated PCM solenoid activation, check function of appropriate solenoid. Solenoid should function as follows.

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. EVR With engine temperature more than 158°F (70°C), solenoid should activate when engine speed is less than 1500 RPM.
6. FPRC Coolant temperature more than 158°F (70°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.
7. HSIA Solenoid should activate when engine speed is less than 5000 RPM.
8. IAC Solenoid should activate during engine cranking and running.
9. VRIS Solenoid should activate with engine at low speed.

CIRCUIT TEST SML - 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. see scheme 4 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.

Sw. Ckts. & Conn. Terminal ID (STG1 - Type "A" Sw. - 1 Of 6). Scheme 120

Sw. Ckts. & Conn. Terminal ID (STG1 - Type "A" Sw. - 2 Of 6). Scheme 121

Sw. Ckts. & Conn. Terminal ID (STG1 - Type "A" Sw. - 3 Of 6). Scheme 122

Sw. Ckts. & Conn. Terminal ID (STG1 - Type "A" Sw. - 4 Of 6). Scheme 123

Sw. Ckts. & Conn. Terminal ID (STG1 - Type "A" Sw. - 5 Of 6). Scheme 124

Sw. Ckts. & Conn. Terminal ID (STG1 - Type "A" Sw. - 6 Of 6). Scheme 125

Sw. Ckts. & Conn. Terminal ID (STG2 - Type "B" Sw. - 1 Of 3). Scheme 126

Sw. Ckts. & Conn. Terminal ID (STG2 - Type "B" Sw. - 2 Of 3). Scheme 127

Sw. Ckts. & Conn. Terminal ID (STG2 - Type "B" Sw. - 3 Of 3). Scheme 128

Sw. Ckts. & Conn. Terminal ID (STG3 - Type "C" Sw. - 1 Of 4). Scheme 129

Sw. Ckts. & Conn. Terminal ID (STG3 - Type "C" Sw. - 2 Of 4). Scheme 130

Sw. Ckts. & Conn. Terminal ID (STG3 - Type "C" Sw. - 3 Of 4). Scheme 131

Sw. Ckts. & Conn. Terminal ID (STG3 - Type "C" Sw. - 4 Of 4). Scheme 132

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 Switch (CPP), 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 12 volts is present with switch closed, adjust switch. See THROTTLE POSITION (TP) SENSOR in ADJUSTMENTS - V6 article in the ENGINE PERFORMANCE section. After adjustment procedure is completed, repeat step 2).

2) Check Switch Signal To PCM Install breakout box. Connect PCM to breakout box. Measure voltage between ground and 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 TESTS W/O CODES - EEC 2.5L article in the ENGINE PERFORMANCE section.

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 5 ohms, repair short to ground in wire between switch and PCM. If testing PSP or IDL switch, if resistance is 5 ohms or more, replace switch. On all other switches, if resistance is 5 ohms or more, go to next step.

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 resistance is less than 5 ohms, replace switch. If resistance is at least 5 ohms, repair open in ground wire.

CIRCUIT TEST STI - 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). see scheme 3 If resistance is less than 5 ohms, go to next step. If resistance is at least 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.

CIRCUIT TEST STO - 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). see scheme 3 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 Circuit & Connector Terminal ID (STP - 2.5L). Scheme 133

Switch Circuit & Connector Terminal ID (STP - 2.5L). Scheme 134

Switch Circuit & Connector Terminal ID (STP - 2.5L). Scheme 135

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 between breakout box test pin of switch being tested and ground. 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, perform CIRCUIT TEST SML. If SML is okay, 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 STEERING COLUMN SWITCHES article in ACCESSORIES/SAFETY EQUIPMENT section. On all other switches, if voltage is not as specified, go to next step.

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.

See also:
• COMPUTER RELEARN PROCEDURES