POWERTRAIN CONTROL MODULE (PCM)
To check PCM ground and power circuits, refer to CIRCUIT TEST PGC in TESTS W/CODES - EEC 2.5L article in the ENGINE PERFORMANCE section.
BAROMETRIC PRESSURE (BARO) SENSOR
BARO sensor is located inside PCM and cannot be serviced separately. Faults in BARO sensor should set a fault code in PCM memory. See CIRCUIT TEST BARO in TESTS W/CODES - EEC 2.5L article in the ENGINE PERFORMANCE section.
Note. Camshaft Position Sensor (CMP) was formerly known as Cylinder Identification (CID) Sensor.
CAMSHAFT POSITION (CMP) SENSOR
CMP sensor is located inside distributor and is integrated with CKP sensor. Faults in CMP sensor should set fault code in PCM memory. See CIRCUIT TEST CID in TESTS W/CODES - EEC 2.5L article in the ENGINE PERFORMANCE section.
CRANKSHAFT POSITION (CKP) SENSOR
CKP sensor is located inside distributor. Probe 2.5L has a second CKP sensor located on front of engine near crankshaft. Faults in CKP sensor should set fault code in PCM memory. See CKP circuit test in TESTS W/CODES - EEC 2.5L article in the ENGINE PERFORMANCE section.
ENGINE COOLANT TEMPERATURE (ECT) SENSOR
Disconnect ECT sensor wiring harness connector. Using DVOM, measure resistance between sensor terminals at specified temperature. See ECT SENSOR SPECIFICATIONS table. Replace sensor if resistance is not as specified.
| Temperature °F (°C) | Ohms |
|---|---|
| 68 (20) | 2200-2700 |
| 104 (40) | 1000-1300 |
| 140 (60) | 500-650 |
| 176 (80) | 250-350 |
ECT SENSOR SPECIFICATIONS
EGR VALVE POSITION (EVP) SENSOR
Faults in EVP sensor should set fault code in PCM memory. See CIRCUIT TEST EVP in TESTS W/CODES - EEC 2.5L article in the ENGINE PERFORMANCE section.
HEATED OXYGEN SENSOR (HO2S)
Continuously rich or lean operation may be caused by malfunction other than HO2S. Faults in HO2S should set fault code in PCM memory. See CIRCUIT TEST HO2S in TESTS W/CODES - EEC 2.5L article in the ENGINE PERFORMANCE section.
INERTIA FUEL SHUTOFF (IFS) SWITCH
- Turn ignition off. Remove IFS switch. IFS switch is located inside of trunk area below left side of floor mat. Strike inertia switch to force switch into tripped position (switch open). Measure resistance between switch terminals. (Scheme 193)
- With IFS switch open (tripped), resistance should be more than 10,000 ohms. With IFS switch closed (set), resistance should be less than 5 ohms. If IFS switch does not test as specified, replace switch.
Scheme 193
INTAKE AIR TEMPERATURE (IAT) SENSOR
Faults in IAT sensor should set fault code in PCM memory. See CIRCUIT TEST IAT in TESTS W/CODES - EEC 2.5L article in the ENGINE PERFORMANCE section.
KNOCK SENSOR (KS)
Faults in knock sensor should set fault code in PCM memory. See CIRCUIT TEST KS in TESTS W/CODES - EEC 2.5L article in the ENGINE PERFORMANCE section.
THROTTLE POSITION (TP) SENSOR
For throttle position sensor specifications and adjustment procedures, see ADJUSTMENTS - 4-CYL article in the ENGINE PERFORMANCE section. For circuit testing, see CIRCUIT TEST TP in TESTS W/CODES - EEC 2.5L article in the ENGINE PERFORMANCE section.
PARK/NEUTRAL POSITION (PNP) SWITCH
For diagnostic procedure, see CIRCUIT TEST STG in appropriate TESTS W/CODES - EEC 2.5L article in the ENGINE PERFORMANCE section.
POWER STEERING PRESSURE (PSP) SWITCH
For diagnostic procedure, see CIRCUIT TEST STG in TESTS W/CODES - EEC 2.5L article in the ENGINE PERFORMANCE section.
VEHICLE SPEED SENSOR (VSS)
Faults in vehicle speed sensor should set fault code in PCM memory. See CIRCUIT TEST VSS in TESTS W/CODES - EEC 2.5L article in the ENGINE PERFORMANCE section.
Ignition Control Module (ICM)
- Turn ignition off. Disconnect a spark plug wire. Connect Spark Tester (D81P-6666-A) to disconnected spark plug wire. Crank engine and observe spark tester. If spark is a continuous strong Blue spark, ICM circuit is okay. If spark is not a continuous strong Blue spark, go to next step.
- Check ICM Signal From PCM Turn ignition off. Install Breakout Box (007-00033). Connect PCM to breakout box. Disconnect distributor 3-pin connector. Crank engine. Measure voltage between ground and ICM test pin (No. 36) at breakout box. If voltage is more than .7 volt, go to next step. If voltage is .7 volt or less, perform CIRCUIT TEST CID and CKP1 in «TESTS W/CODES - EEC 2.5L»(ref-22894) article in the ENGINE PERFORMANCE section. If results of both circuit tests are okay, replace PCM.
- Check For Open ICM Wire Disconnect 6-pin distributor connector. Measure resistance between ICM test pin (No. 36) at breakout box and ICM terminal (Blue/Orange wire) at distributor 6-pin connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open Blue/Orange wire.
- Check For Short ICM Wire Measure resistance between ground and ICM test pin (No. 36) 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 Blue/Orange wire.
- Check Ground At Distributor Measure resistance between ground and GND terminals (Black/White wire and Black/Red wire) at distributor 6-pin connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open GND wire.
- Check Power To Distributor Turn ignition on. Measure voltage at PWR terminal (Black/Pink wire) of distributor 3-pin connector. If voltage is more than 10 volts, replace distributor. If voltage is 10 volts or less, repair PWR wire between distributor and ignition switch.
EGR Control Solenoid
Disconnect vacuum and electrical connections from solenoid. Apply vacuum to EGR control solenoid port "A", vacuum should hold. (Scheme 194) Using jumper wire, connect negative terminal to ground and apply 12 volts to positive terminal, vacuum should release. Replace solenoid if it does not operate as specified.
Scheme 194
EGR Vent Solenoid
Disconnect vacuum and electrical connections from solenoid. Apply low air pressure into EGR vent solenoid port "C" and ensure air pressure flows through port "E" of solenoid. (Scheme 194) Using jumper wire, connect negative terminal to ground and apply 12 volts to positive terminal. Apply low air pressure to vent solenoid port "C" and ensure air pressure does not flow to port "E". Replace solenoid if it does not operate as specified.
EVAP Canister Purge Solenoid
Disconnect vacuum and electrical connections from solenoid. Apply low air pressure to port "A" of solenoid and ensure air pressure does not flow from port "B" of solenoid. (Scheme 195) Using jumper wires, connect negative terminal to ground and apply 12 volts to positive terminal. Apply low air pressure to solenoid port "A" and ensure air flows through port "B" of solenoid. Replace solenoid if it does not test as specified.
Idle Air Control (IAC) Solenoid
Faults in IAC solenoid should set fault code in PCM memory. For diagnostic procedure, see CIRCUIT TEST SCG in TESTS W/CODES - EEC 2.5L article in the ENGINE PERFORMANCE section.
Scheme 195
FUEL SYSTEM
Note. For fuel pressure specifications, see FUEL PRESSURE SPECIFICATIONS article.
FUEL PRESSURE RELEASE
Remove fuel pump relay or disconnect Inertia Fuel Shutoff (IFS) switch. Fuel pump relay is located in engine compartment main fuse panel. IFS switch is located luggage compartment. Start engine and operate it until it stalls. Turn ignition off. Reconnect fuel pump relay or IFS switch. See INERTIA FUEL SHUTOFF (IFS) SWITCH under ENGINE SENSORS & SWITCHES.
Fuel Pressure Check
Release fuel pressure. See FUEL PRESSURE RELEASE. Install Fuel Pressure Gauge (014-00748) between fuel filter and fuel rails. Ensure pressure gauge drain valve is closed and main valve is open. Using jumper wire, connect Data Link Connector (DLC) fuel pump terminal to ground terminal. (Scheme 196) For fuel pressure specifications, see FUEL PRESSURE SPECIFICATIONS article. Turn ignition on, but do not start engine. Observe gauge reading, and proceed as follows
- If fuel pressure is zero, go to appropriate NO FUEL PRESSURE.
- If fuel pressure is low, go to LOW FUEL PRESSURE.
- If fuel pressure is high, go to HIGH FUEL PRESSURE.
- If fuel pressure is normal, go to FUEL INJECTOR TEST.
Scheme 196
Scheme 197
- Turn ignition off. Check if Inertia Fuel Shutoff (IFS) switch has been tripped. IFS switch is located inside of trunk area below left side of floor mat. Reset IFS switch if tripped. Repeat FUEL PRESSURE CHECK. If IFS switch is okay, connect Data Link Connector (DLC) fuel pump test terminal to ground terminal using jumper wire. (Scheme 196) Disconnect fuel pump connector at fuel pump. Measure voltage at Black/White wire at fuel pump connector. If voltage is not 10-14 volts, go to next step. If voltage is 10-14 volts, go step 8).
- Turn ignition off. Remove fuel pump relay. Relay is located in engine compartment fuse box. Disconnect Powertrain Control Module (PCM). Ensure fuel pump is disconnected. Measure voltage between ground, and Light Green and White/Yellow wires at fuel pump relay connector. If resistances are 10,000 ohms or more, go to next step. If resistances are less than 10,000 ohms, repair short in wires as necessary.
- Turn ignition off. Ensure fuel pump relay is disconnected. Turn ignition on. Check for battery voltage at Red/Black wire of fuel pump relay connector. If voltage is as specified, go to next step. If voltage is not as specified, proceed to CIRCUIT TEST VPWR in «TESTS W/CODES - EEC 2.5L»(ref-22894) article in the ENGINE PERFORMANCE section. If VPWR circuit is okay, repair open in Red/Black wire.
- Apply battery voltage between terminals "A" and "B" of fuel pump relay. (Scheme 197) Measure resistance between terminals "C" and "D". Resistance should be less than 5 ohms. With no battery voltage applied to relay, resistance between terminals "C" and "D" should be more than 10,000 ohms. If resistance is not as specified, replace relay. If resistance is as specified, go to next step.
- Turn ignition off. Ensure fuel pump relay and PCM are disconnected. Install Breakout Box (007-00033). Measure resistance between test pin No. 52B of breakout box and Light Green wire at fuel pump relay. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open Light Green wire between fuel pump relay and PCM.
- Check IFS switch. See INERTIA FUEL SHUTOFF (IFS) SWITCH under ENGINE SENSORS & SWITCHES. Replace IFS switch if defective. If switch is okay, go to next step.
- Ensure ignition is off and fuel pump relay is disconnected. Disconnect IFS switch connector. Measure resistance of White/Yellow wire between IFS switch connector and fuel pump relay connector. If resistance is less than 5 ohms, repair open wire between IFS switch and fuel pump. If resistance is 5 ohms or more, repair open White/Yellow wire between IFS switch and fuel pump relay.
- If voltage was 10-14 volts in step 1), turn ignition off. Disconnect fuel pump connector. Measure resistance between ground and Black wire at fuel pump connector. If resistance is less than 5 ohms, replace fuel pump. If resistance is 5 ohms or more, repair open ground wire.
Scheme 198
- Turn ignition off. Using jumper wire, connect Data Link Connector (DLC) fuel pump test terminal to ground terminal. (Scheme 196) Disconnect fuel pump connector. Turn ignition on. Measure voltage between ground and Black/White wire at fuel pump connector. If battery voltage is present, go to next step. If battery voltage is not present, go to appropriate NO FUEL PRESSURE.
- Turn ignition off. Release fuel system pressure. See FUEL PRESSURE RELEASE. Remove fuel filter. Inspect filter for restriction and contamination. Replace fuel filter if necessary, and recheck fuel pressure. If fuel filter is okay, go to next step.
- With fuel pressure released, install fuel pressure gauge between fuel filter and fuel rails. Ensure pressure gauge main valve is open and drain valve is closed. Start engine and run it for 10 seconds. Stop engine and wait for 10 seconds. Start engine again and run it for 10 seconds.
- Stop engine, and remove vacuum hose from pressure regulator. Check pressure regulator for fuel leakage through diaphragm. (Scheme 198) If fuel is present, replace pressure regulator. If fuel is not present, go to next step.
- Reconnect vacuum hose. Start engine. Run it for 30 seconds. Stop engine and observe fuel pressure after 5 minutes. If fuel pressure is more than 21 psi, go to next step. If fuel pressure is 21 psi or less, start engine and let run for 30 seconds. Stop engine and wait 5 minutes. If fuel pressure is still less than 21 psi, check fuel injectors for leakage. See FUEL INJECTOR TEST. If okay, replace pressure regulator and repeat test.
- Disconnect fuel return hose at fuel pressure regulator. Connect vacuum gauge to fuel return tube of fuel pressure regulator. Apply 20 in. Hg of vacuum for 10 seconds. If vacuum does not drop to less than 10 in. Hg, go to next step. If vacuum drops to less than 10 in. Hg, replace pressure regulator.
- Place fuel pressure gauge drain hose into an empty metal container. Using jumper wire, connect fuel pump terminal to ground terminal to activate fuel pump. (Scheme 196) Turn ignition on for 10 seconds. Measure fuel volume. If fuel volume is 5.5 ounces or more, go to next step. If fuel volume is less than 5.5 ounces, service fuel pump inlet screen and repeat fuel volume test. If fuel volume is still less than specified, replace fuel pump.
- Using a jumper wire, connect fuel pump terminal to ground terminal to activate fuel pump. Turn ignition on. Operate fuel pump for 30 seconds. Observe fuel pressure gauge for 3 minutes. If fuel pressure does not decrease more than 2 psi, replace fuel pump. If fuel pressure decreases more than 2 psi, check for leaking fuel injector. See FUEL INJECTOR TEST.
High Fuel Pressure
- Check for engine vacuum leaks. Check for loose or cross threaded fittings, cracks, and blockage which could cause insufficient vacuum supply to fuel pressure regulator. Repair vacuum leaks as necessary. If no vacuum leaks are found, go to next step.
- Check fuel pressure regulator housing for damage and dents which could cause a higher spring load on regulator. Check fuel pressure regulator diaphragm operation. See steps 3) and 4) in LOW FUEL PRESSURE test. If fuel pressure regulator is okay, go to next step. Replace fuel pressure regulator if defective, and recheck fuel pressure.
- Disconnect fuel return line from fuel pressure regulator and fuel tank. Place disconnected hose at fuel tank into an empty container. Using low air pressure (5-10 psi), blow air into disconnected return line at pressure regulator. If fuel return line is restricted, clean or repair return line as necessary and repeat fuel pressure test. If fuel return line is free of restrictions, replace fuel pressure regulator and repeat fuel pressure test. If fuel pressure is still high, replace fuel pressure regulator and recheck fuel pressure.
EGR Valve
Perform visual inspection of physical condition of valve, inspect vacuum hoses and electrical connections. Ensure engine is at normal operating temperature. Turn ignition off. Disconnect EGR valve vacuum supply hose. Connect vacuum pump to disconnected vacuum hose. Start engine. Allow engine to idle. Apply 1.6-2.4 in. Hg of vacuum. Engine should run rough or stall. Clean or replace valve if it does not operate as specified.