Engine Controls - System & Component Testing: Other Jeep Wrangler II

POWERTRAIN CONTROL MODULE

Note. If replacing Powertrain Control Module (PCM), the correct vehicle mileage and Vehicle Identification Number (VIN) must be programmed into PCM to prevent Diagnostic Trouble Codes (DTC) from being stored in Anti-Lock Brake System (ABS) module and Air Bag Control Module (ACM). If replacing PCM on models equipped with a Sentry Key Immobilizer Module (SKIM), the secret key data must also be updated to enable engine starting.

Programming Powertrain Control Module

Connect scan tool to Data Link Connector (DLC) located below instrument panel, near steering column. Using scan tool, enter correct VIN and mileage into PCM. Using scan tool manufacturer's instructions, clear DTCs from ABS module and ACM.

Updating Secret Key Data

1. Connect scan tool to Data Link Connector (DLC) located below instrument panel, near steering column. Ensure transmission is in Park (A/T) or Neutral (M/T). Turn ignition on.
2. Using scan tool, select THEFT ALARM, SKIM and then MISCELLANEOUS. Select PCM REPLACED. Place the SKIM in SECURED ACCESS MODE by entering the appropriate Personal Identification Number (PIN) for this vehicle. PIN may be obtained from the owner, vehicle's invoice, or from the manufacturer. Press ENTER to transfer secret key data from Sentry Key Immobilizer Module (SKIM) to the PCM. This will enable the vehicle to start.
3. If 3 attempts are made to enter the SECURED ACCESS MODE by using an incorrect PIN, the SECURED ACCESS MODE will be locked out for one hour. To exit lock out mode, leave ignition on with all accessories turned off. After one hour, enter correct PIN. It may be necessary to monitor battery voltage and connect a battery charger.

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-1 under VERIFICATION TESTS to ensure system is functioning properly.

Checking Powertrain Control Module (PCM) Power & Ground Circuits (Cherokee)

1. Turn ignition off. Disconnect PCM Black C1 connector. PCM is located in engine compartment on left front fender, near radiator support. Inspect connector for damaged pins, corrosion and loose terminals. Repair connector as necessary. Using a test light connected to ground, probe terminal No. 22 (Dark Green/Black wire) at PCM C1 connector. (Scheme 7) If test light illuminates brightly, go to next step. If test light does not illuminate brightly, repair open fused B(+) circuit (Dark Green/Black wire) between PCM and fuse No. 22 (15-amp) in Power Distribution Center (PDC). PDC is located in right side of engine compartment, next to battery. Also check fuse No. 22 in PDC. See WIRING DIAGRAMS article.
2. Turn ignition on. Using a test light connected to ground, probe terminal No. 2 (Dark Blue/White wire) at PCM C1 connector. (Scheme 7) If test light illuminates brightly, power circuits are okay. Go to next step. If test light does not illuminate brightly, repair open fused ignition switch output circuit (Dark Blue/White wire) between PCM and fuse No. 11 (20-amp) in junction block. Junction block is located behind passenger-side kick panel. Also check fuse No. 11 in junction block.
3. Turn ignition off. Using a test light connected to positive battery voltage, probe terminals No. 31 (Black/Tan wire) and No. 32 (Black/Tan wire) at PCM C1 connector. If test light illuminates brightly at both terminals, ground circuits are okay. Test is complete. If test light does not illuminate brightly at one or both terminals, repair open in appropriate Black/Tan wire between PCM and ground. Ground location is located at right front of cylinder block, near generator.

Scheme 7

Checking Powertrain Control Module (PCM) Power & Ground Circuits (Grand Cherokee)

1. Turn ignition off. Disconnect PCM Black C1 connector. PCM is located on firewall in right rear corner of engine compartment. Inspect connector for damaged pins, corrosion and loose terminals. Repair connector as necessary. Using a test light connected to ground, probe terminal No. 22 (Red/Black wire) at PCM C1 harness connector. (Scheme 7) If test light illuminates brightly, go to next step. If test light does not illuminate brightly, repair open fused B(+) circuit (Red/Black wire) between fuse No. 19 (10-amp) in Power Distribution Center (PDC) and PCM. PDC is located in right side of engine compartment, next to battery. Also check fuse No. 19 in PDC. See WIRING DIAGRAMS article.
2. Turn ignition on. Using a test light connected to ground, probe terminal No. 2 (Orange/Dark Blue wire) at PCM C1 connector. (Scheme 7) If test light illuminates brightly, go to next step. If test light does not illuminate brightly, repair open fused ignition switch output circuit (Orange/Dark Blue wire) between fuse No. 12 (10-amp) in junction block and PCM. Junction block is located under left side of instrument panel. Also check fuse No. 12 in junction block.
3. Turn ignition off. Using a test light connected to positive battery voltage, probe terminals No. 31 (Black/White wire) and No. 32 (Black/Tan wire) at PCM C1 connector. If test light illuminates brightly at both terminals, ground circuits are okay. Test is complete. If test light does not illuminate brightly at one or both terminals, repair open in Black/White and/or Black/Tan wire between PCM and ground. Ground connection is located on right side of cylinder block.

Checking Powertrain Control Module (PCM) Power & Ground Circuits (Wrangler)

1. Turn ignition off. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connector for damaged pins, corrosion and loose terminals. Repair connector as necessary. Using a test light connected to ground, probe terminal A22 (Red/White wire) at PCM C1 harness connector. (Scheme 8) If test light illuminates brightly, go to next step. If test light does not illuminate brightly, repair open fused B(+) circuit (Red/White wire) between fuse No. 9 (30-amp) in Power Distribution Center (PDC) and PCM. PDC is located in right side of engine compartment, next to battery. See WIRING DIAGRAMS article. Also check fuse No. 9 in PDC.
2. Turn ignition on. Using a test light connected to ground, probe terminal C3 (Dark Blue/Yellow wire) at PCM C3 harness connector. (Scheme 8) If test light illuminates brightly, power circuits are okay. Go to next step. If test light does not illuminate brightly, repair open fused ignition switch output circuit (Dark Blue/Yellow wire) between fuse No. 12 (10-amp) in fuse block and PCM. Fuse block is located behind glove box. Also check fuse No. 12 in fuse block.
3. Turn ignition off. Using a test light connected to positive battery voltage, probe terminals A31 (Black/Tan wire) and A32 (Black/Tan wire) at PCM C1 connector. If test light illuminates brightly at both terminals, ground circuits are okay. Test is complete. If test light does not illuminate brightly at one or both terminals, repair open in appropriate Black/Tan wire between PCM and ground. Ground connection is located on right rear of cylinder block.

Scheme 8

CAMSHAFT POSITION SENSOR

For camshaft position sensor testing, see DTC P0340: NO CAM SIGNAL AT PCM under DIAGNOSTIC TESTS in appropriate SELF-DIAGNOSTICS article.

CHECKING ENGINE COOLANT TEMPERATURE SENSOR

Note. The following procedure assumes that the cooling system thermostat is functioning properly. Test works best if performed on a totally cold engine (cold soak).

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-2 under VERIFICATION TESTS to ensure system is functioning properly.

1. Turn ignition on. Using scan tool, read Engine Coolant Temperature (ECT) sensor value. If engine coolant temperature is more than 180°F (82°C), allow engine coolant temperature to cool down to 150°F (66°C) before proceeding. If engine coolant temperature is 150°F (66°C) or less, start engine and monitor scan tool until engine coolant temperature reaches 180°F (82°C). If ECT sensor value increases smoothly, go to next step. If ECT sensor value increase is erratic, check for cooling system problems and repair as necessary. If cooling system is okay, replace ECT sensor.
2. If coolant temperature reaches 180°F (82°C) or more, no problem is indicated at this time. Test is complete. If coolant temperature does not reach 180°F (82°C) or more, check for cooling system problems and repair as necessary. If cooling system is okay, replace ECT sensor.

CHECKING INTAKE AIR TEMPERATURE SENSOR

Note. When performing this test, DO NOT allow more than 5 minutes between measuring temperature of Intake Air Temperature (IAT) sensor with scan tool and measuring the air temperature inside of intake manifold with temperature probe.

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-2 under VERIFICATION TESTS to ensure system is functioning properly.

Turn ignition on. Using scan tool, read and record IAT sensor value. Remove IAT sensor. (Scheme 9)- (Scheme 11). Using a thermometer, read temperature inside IAT sensor opening. If IAT sensor value is within 10 degrees of thermometer reading, reinstall IAT sensor. IAT sensor is operating properly. Test is complete. If IAT sensor value is not within 10 degrees of thermometer reading, replace IAT sensor.

Scheme 9

Scheme 10

Scheme 11

Scheme 12

CHECKING PARK/NEUTRAL POSITION SWITCH (A/T)

For park/neutral position switch testing, see DTC P1899: P/N SWITCH PERFORMANCE under DIAGNOSTIC TESTS in appropriate SELF-DIAGNOSTICS article.

CRANKSHAFT POSITION SENSOR

For crankshaft position sensor testing, see DTC P0320: NO CRANK REFERENCE SIGNAL AT PCM under DIAGNOSTIC TESTS in appropriate SELF-DIAGNOSTICS article.

LEAK DETECTION PUMP SWITCH

For leak detection pump switch testing, see DTC P1494: LEAK DETECTION PUMP SW OR MECHANICAL FAULT under DIAGNOSTIC TESTS in appropriate SELF-DIAGNOSTICS article.

POWER STEERING SWITCH (2.5L)

For power steering switch testing, see DTC P0551: POWER STEERING SWITCH FAILURE under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - WRANGLER article.

VEHICLE SPEED SENSOR

For vehicle speed sensor testing, see DTC P0500: NO VEHICLE SPEED SENSOR SIGNAL under DIAGNOSTIC TESTS in appropriate SELF-DIAGNOSTICS article.

A/C CLUTCH RELAY

Note. For A/C clutch relay circuit testing, see DTC P0645: A/C CLUTCH RELAY CIRCUIT under DIAGNOSTIC TESTS in appropriate SELF-DIAGNOSTICS article.

1. Turn ignition off. Remove A/C clutch relay from Power Distribution Center (PDC). PDC is located in engine compartment, near battery. (Scheme 13), (Scheme 14) or (Scheme 15). Using an ohmmeter, check for continuity between A/C clutch relay terminals No. 30 and 87. (Scheme 16) If continuity exists, replace relay. If continuity does not exist, go to next step.
2. Measure resistance between A/C clutch relay terminals No. 85 and 86. (Scheme 16) If resistance is not 50-90 ohms, replace A/C clutch relay. If resistance is 50-90 ohms, go to next step.
3. Using jumper wires, apply positive battery voltage to relay terminal No. 86 and ground relay terminal No. 85. Check for continuity between relay terminals No. 30 and 87. Continuity should exist. If continuity does not exist, replace A/C clutch relay.

Scheme 13

Scheme 14

Scheme 15

Scheme 16

AUTO SHUTDOWN RELAY

Note. For auto shutdown relay circuit testing, see DTC P1388: AUTO SHUTDOWN RELAY CONTROL CIRCUIT under DIAGNOSTIC TESTS in appropriate SELF-DIAGNOSTICS article.

1. Turn ignition off. Remove Auto Shutdown (ASD) relay from Power Distribution Center (PDC). PDC is located in engine compartment, near battery. (Scheme 13), (Scheme 14) or (Scheme 15). Using an ohmmeter, check for continuity between ASD relay terminals No. 30 and 87. (Scheme 16)or (Scheme 17). If continuity exists, replace relay. If continuity does not exist, go to next step.
2. Measure resistance between ASD relay terminals No. 85 and 86. If resistance is not 50-80 ohms, replace ASD relay. If resistance is 50-80 ohms, go to next step.
3. Using jumper wires, apply positive battery voltage to relay terminal No. 86 and ground relay terminal No. 85. Check for continuity between relay terminals No. 30 and 87. Continuity should exist. If continuity does not exist, replace ASD relay.

Scheme 17

EVAPORATIVE PURGE SOLENOID

For evaporative purge solenoid testing, see DTC P0443: EVAP PURGE SOLENOID CIRCUIT under DIAGNOSTIC TESTS in appropriate SELF-DIAGNOSTICS article.

FUEL PUMP RELAY

Note. For fuel pump relay circuit testing, see DTC P1282: FUEL PUMP RELAY CONTROL CIRCUIT under DIAGNOSTIC TESTS in appropriate SELF-DIAGNOSTICS article.

1. Turn ignition off. Remove fuel pump relay from Power Distribution Center (PDC). PDC is located in engine compartment, near battery. (Scheme 13), (Scheme 14) or (Scheme 15). Using an ohmmeter, check for continuity between fuel pump relay terminals No. 30 and 87. (Scheme 16) If continuity exists, replace relay. If continuity does not exist, go to next step.
2. Measure resistance between fuel pump relay terminals No. 85 and 86. If resistance is not 50-90 ohms, replace fuel pump relay. If resistance is 50-90 ohms, go to next step.
3. Using jumper wires, apply positive battery voltage to relay terminal No. 86 and ground relay terminal No. 85. Check for continuity between relay terminals No. 30 and 87. Continuity should exist. If continuity does not exist, replace relay.

IDLE AIR CONTROL MOTOR

For idle air control motor testing, see IDLE CONTROL SYSTEMS .

Cherokee & Grand Cherokee (4.0L)

1. Turn ignition off. On Cherokee, remove radiator fan relay from Power Distribution Center (PDC). PDC is located in engine compartment, near battery. (Scheme 13) On Grand Cherokee, disconnect radiator fan relay connector. Radiator fan relay is located behind right bumper fascia, below right headlight assembly. On all models, check for continuity between radiator fan relay terminals No. 30 and 87. (Scheme 17) If continuity exists, replace relay. If continuity does not exist, go to next step.
2. Measure resistance between radiator fan relay terminals No. 85 and 86. If resistance is not 50-90 ohms, replace radiator fan relay. If resistance is 50-90 ohms, go to next step.
3. Using jumper wires, apply positive battery voltage to relay terminal No. 86 and ground relay terminal No. 85. Check for continuity between relay terminals No. 30 and 87. Continuity should exist. If continuity does not exist, replace radiator fan relay.

FUEL SYSTEM PRESSURE RELEASE

1. Remove fuel pump relay from Power Distribution Center (PDC). PDC is located in right side of engine compartment, next to battery. (Scheme 13), (Scheme 14) or (Scheme 15). Start and run engine until it stalls. Attempt to start engine. Continue restarting engine until it will no longer run. Turn ignition off. NOTE: One or more Diagnostic Trouble Codes (DTC) may set when fuel pump relay is removed.
2. Disconnect any fuel injector connector. Connect a jumper wire between either fuel injector terminal and positive battery terminal. Connect another jumper wire to other fuel injector terminal. Momentarily touch other end of jumper wire to negative battery terminal. CAUTION: DO NOT supply power to fuel injector for more than 4 seconds, or fuel injector may be damaged.
3. Place a shop towel under fuel line quick-connector at fuel rail. Use care when disconnecting fuel lines, as some fuel pressure may still exist in fuel lines. Disconnect fuel line quick-connector at fuel rail. Reinstall fuel pump relay in PDC. Reconnect fuel line quick-connector. Using scan tool, erase any DTCs that may have set after fuel pressure release procedure.

FUEL DELIVERY

Note. For fuel system pressure testing, see FUEL PRESSURE TEST under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES article. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-1 under VERIFICATION TESTS to ensure system is functioning properly.

Checking Fuel Delivery (Cherokee)

1. Turn ignition on. Using scan tool, actuate ASD fuel system test. Listen for fuel pump operation at fuel tank. It may be necessary to use a stethoscope. If fuel pump operation can be heard, fuel pump is operating. Stop fuel system activation and go to next step. If fuel pump operation cannot be heard, stop fuel system activation and go to step 7.
2. Release fuel pressure. See «FUEL SYSTEM PRESSURE RELEASE»(ref-12052-S15450743302000120600000). Remove test port cap on fuel rail. Install a 0-60 psi (0-4.2 kg/cm 2 ) fuel pressure gauge at test port. Start engine and allow to idle. Fuel pressure should be 44.2-54.2 psi (3.1-3.7 kg/cm 2 ). If fuel pressure is less than specified, go to next step. If fuel pressure is more than specified, fuel pump is okay, but fuel pressure regulator is defective. Release fuel pressure and replace fuel pressure regulator. See FUEL FILTER/FUEL PRESSURE REGULATOR under FUEL SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION article. If fuel pressure is as specified, go to step 5.
3. Release fuel pressure. Raise and support vehicle. Disconnect fuel pressure line from fuel filter/pressure regulator at fuel tank. Connect Fuel Line Pressure Test Adapter Hose (6539) between disconnected fuel line and fuel filter/pressure regulator. Connect fuel pressure gauge to fuel line adapter hose. Turn ignition on. Using scan tool, actuate ASD fuel system test and note fuel pressure. Fuel pressure should be 44.2-54.2 psi (3.23-3.96 kg/cm 2 ). If fuel pressure is as specified, stop ASD fuel system activation. Release fuel pressure, and repair or replace fuel supply line. If fuel pressure is not as specified, stop ASD fuel system activation and go to next step.
4. Release fuel pressure. Remove fuel pump module and inspect fuel inlet strainer. See FUEL PUMP MODULE under FUEL SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION article. If fuel inlet strainer is plugged, replace fuel pump inlet strainer. If fuel inlet strainer in not plugged, replace fuel pump.
5. Turn ignition off. Release fuel pressure. Disconnect fuel supply line from fuel rail. Install Fuel Line Pressure Test Adapter Hose (6539 for 5/16" fuel lines or 6631 for 3/8" fuel lines) between disconnected fuel line and fuel rail. Remove fuel fill cap. Insert other end of hose into a graduated container suitable for gasoline.
6. Using scan tool, actuate ASD fuel system test for 7 seconds. If fuel volume is.5 pt. (.25L) or more, no problem is indicated at this time. Test is complete. If fuel volume is less than.5 pt. (.25L), check for a kinked fuel line between fuel pump module and fuel rail. Repair fuel lines as necessary and retest. If fuel line is okay, replace fuel pump module assembly. See FUEL PUMP MODULE under FUEL SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION article.
7. Turn ignition off. Disconnect fuel pump module connector. Turn ignition on. Using scan tool, actuate ASD fuel system test. Using a test light connected to ground, probe Dark Green/White wire at fuel pump module harness connector. If test light illuminates brightly, go to next step. If test light does not illuminate brightly, go to step 10.
8. Turn ignition off. Disconnect test light. Using a test light connected to positive battery voltage, probe Black wire at fuel pump module harness connector. If test light illuminates brightly, go to next step. If test light does not illuminate brightly, repair open in Black wire between ground and fuel pump module. See WIRING DIAGRAMS article.
9. At this time, fuel pump module is assumed to be defective. Replace fuel pump module.
10. Turn ignition off. Ensure fuel pump module is disconnected. Remove fuel pump relay from PDC. Using a test light connected to ground, probe Dark Green/Black wire at terminal C1 at fuel pump relay socket in PDC. (Scheme 13) If test light illuminates, go to next step. If test light does not illuminate, repair open in Dark Green/Black wire between fuel pump relay socket and PDC. Also check fuse No. 22 (15-amp) in PDC.
11. Measure resistance of Dark Green/White wire between fuel pump module harness connector and terminal C2 at fuel pump relay socket in PDC. (Scheme 13) If resistance is less than 5 ohms, circuit is okay. Replace fuel pump relay. If resistance is 5 ohms or more, repair open in Dark Green/White wire between fuel pump module and PDC.

Scheme 18

1. Turn ignition on. Using scan tool, actuate ASD fuel system test. Listen for fuel pump operation at fuel tank. It may be necessary to use a stethoscope. If fuel pump operation can be heard, fuel pump is operating. Stop fuel system activation and go to next step. If fuel pump operation cannot be heard, stop fuel system activation and go to step 7.
2. Release fuel pressure. See «FUEL SYSTEM PRESSURE RELEASE»(ref-12052-S15450743302000120600000). Remove test port cap on fuel rail. Install a 0-60 psi (0-4.2 kg/cm 2 ) fuel pressure gauge at test port. Start engine and allow to idle. Fuel pressure should be 44.2-54.2 psi (3.1-3.7 kg/cm 2 ). If fuel pressure is less than specified, go to next step. If fuel pressure is more than specified, check fuel return line for kinks or restrictions. (Scheme 18) Repair fuel return line as necessary. If fuel return line is okay, replace fuel filter/pressure regulator. See FUEL FILTER/FUEL PRESSURE REGULATOR under FUEL SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION article. If fuel pressure is as specified, go to step 5.
3. If engine runs but fuel pressure is less than specified, check for kinked or damaged fuel supply line between fuel pump module and fuel rail. Repair fuel line as necessary and retest. If fuel line is okay, release fuel pressure. Raise and support vehicle. Disconnect fuel pressure line from fuel filter/pressure regulator. (Scheme 18) Connect Fuel Line Pressure Test Adapter Hose (6539) between disconnected fuel line and fuel filter/pressure regulator. Connect fuel pressure gauge to fuel line adapter hose. Turn ignition on, with engine off. Using scan tool, actuate ASD fuel system test and note fuel pressure. Fuel pressure should be 44.2-54.2 psi (3.23-3.96 kg/cm 2 ). If fuel pressure is within specification, stop ASD fuel system activation, release fuel pressure and replace fuel filter/pressure regulator. If fuel pressure is not within specification, stop ASD fuel system activation and go to next step.
4. Turn ignition off. Release fuel pressure. Remove fuel pump module and inspect fuel inlet strainer. See FUEL PUMP MODULE under FUEL SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION article. If fuel inlet strainer is plugged, replace fuel pump inlet strainer. If fuel inlet strainer in not plugged, replace fuel pump.
5. Turn ignition off. Release fuel pressure. Disconnect fuel supply line from fuel rail. Install Fuel Line Pressure Test Adapter Hose (6539 for 5/16" fuel lines or 6631 for 3/8" fuel lines) between disconnected fuel line and fuel rail. Remove fuel fill cap. Insert other end of hose into a graduated container suitable for gasoline.
6. Using scan tool, actuate ASD fuel system test for 7 seconds. If fuel volume is.5 pt. (.25L) or more, no problem is indicated at this time. Test is complete. If fuel volume is less than.5 pt. (.25L), check for a kinked fuel line between fuel pump module and fuel rail. Repair fuel lines as necessary and retest. If fuel line is okay, replace fuel pump module assembly. See FUEL PUMP MODULE under FUEL SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION article.
7. Turn ignition off. Disconnect fuel pump module connector. Turn ignition on. Using scan tool, actuate ASD fuel system test. Using a test light connected to ground, probe Dark Green/Black wire at fuel pump module harness connector. If test light illuminates brightly, go to next step. If test light does not illuminate brightly, go to step 10.
8. Turn ignition off. Disconnect test light. Using a test light connected to positive battery voltage, probe Black wire at fuel pump module harness connector. If test light illuminates brightly, go to next step. If test light does not illuminate brightly, repair open in Black wire between ground and fuel pump module. See WIRING DIAGRAMS article.
9. At this time, fuel pump module is assumed to be defective. Replace fuel pump module.
10. Turn ignition off. Ensure fuel pump module is disconnected. Remove fuel pump relay from PDC. Using a test light connected to ground, probe terminal No. 30 (Violet/White wire) at fuel pump relay socket in PDC. (Scheme 14) If test light illuminates, go to next step. If test light does not illuminate, repair open in Violet/White wire between fuel pump relay socket and PDC. Also check fuse No. 24 (20-amp) in PDC.
11. Measure resistance of Dark Green/Black wire between fuel pump module harness connector and terminal No. 87 at fuel pump relay socket in PDC. (Scheme 14) If resistance is less than 5 ohms, circuit is okay. Replace fuel pump relay. If resistance is 5 ohms or more, repair open in Dark Green/Black wire between fuel pump module and PDC.

Checking Fuel Delivery (Wrangler)

1. Turn ignition on. Using scan tool, actuate ASD fuel system test. Listen for fuel pump operation at fuel tank. It may be necessary to use a stethoscope. If fuel pump operation can be heard, fuel pump is operating. Stop fuel system activation and go to next step. If fuel pump operation cannot be heard, stop fuel system activation and go to step 7.
2. Release fuel pressure. See «FUEL SYSTEM PRESSURE RELEASE»(ref-12052-S15450743302000120600000). Remove test port cap on fuel rail. Install a 0-60 psi (0-4.2 kg/cm 2 ) fuel pressure gauge at test port. Start engine and allow to idle. Fuel pressure should be 44.2-54.2 psi (3.1-3.7 kg/cm 2 ). If fuel pressure is less than specified, go to next step. If fuel pressure is more than specified, fuel pump is okay, but fuel pressure regulator is defective. Release fuel pressure and replace fuel pressure regulator. See FUEL FILTER/FUEL PRESSURE REGULATOR under FUEL SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION article. If fuel pressure is as specified, go to step 5.
3. Release fuel pressure. Raise and support vehicle. Disconnect fuel pressure line from fuel filter/pressure regulator at fuel tank. Connect Fuel Line Pressure Test Adapter Hose (6539) between disconnected fuel line and fuel filter/pressure regulator. Connect fuel pressure gauge to fuel line adapter hose. Turn ignition on. Using scan tool, actuate ASD fuel system test and note fuel pressure. Fuel pressure should be 44.2-54.2 psi (3.23-3.96 kg/cm 2 ). If fuel pressure is as specified, stop ASD fuel system activation. Release fuel pressure, and repair or replace fuel supply line. If fuel pressure is not as specified, stop ASD fuel system activation and go to next step.
4. Turn ignition off. Release fuel pressure. Remove fuel pump module and inspect fuel inlet strainer. See FUEL PUMP MODULE under FUEL SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION article. If fuel inlet strainer is plugged, replace fuel pump inlet strainer. If fuel inlet strainer in not plugged, replace fuel pump.
5. Turn ignition off. Release fuel pressure. Disconnect fuel supply line from fuel rail. Install Fuel Line Pressure Test Adapter Hose (6539 for 5/16" fuel lines or 6631 for 3/8" fuel lines) between disconnected fuel line and fuel rail. Remove fuel fill cap. Insert other end of hose into a graduated container suitable for gasoline.
6. Using scan tool, actuate ASD fuel system test for 7 seconds. If fuel volume is.5 pt. (.25L) or more, no problem is indicated at this time. Test is complete. If fuel volume is less than.5 pt. (.25L), check for a kinked fuel line between fuel pump module and fuel rail. Repair fuel lines as necessary and retest. If fuel line is okay, replace fuel pump module assembly. See FUEL PUMP MODULE under FUEL SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION article.
7. Turn ignition off. Disconnect fuel pump module connector. Turn ignition on. Using scan tool, actuate ASD fuel system test. Using a test light connected to ground, probe Dark Green/White wire at fuel pump module harness connector. If test light illuminates brightly, go to next step. If test light does not illuminate brightly, go to step 10.
8. Turn ignition off. Disconnect test light. Using a test light connected to positive battery voltage, probe Black wire at fuel pump module harness connector. If test light illuminates brightly, go to next step. If test light does not illuminate brightly, repair open in Black wire between ground and fuel pump module. See WIRING DIAGRAMS article.
9. At this time, fuel pump module is assumed to be defective. Replace fuel pump module.
10. Turn ignition off. Ensure fuel pump module is disconnected. Remove fuel pump relay from PDC. Using a test light connected to ground, probe at terminal C10 (Dark Green/Black wire) at fuel pump relay socket in PDC. (Scheme 15) If test light illuminates, go to next step. If test light does not illuminate, repair open in Dark Green/Black wire between fuel pump relay socket and PDC. Also check fuse No. 23 (20-amp) in PDC.
11. Measure resistance of Dark Green/White wire between fuel pump module harness connector and terminal C9 at fuel pump relay socket in PDC. (Scheme 15) If resistance is less than 5 ohms, circuit is okay. Replace fuel pump relay. If resistance is 5 ohms or more, repair open in Dark Green/White wire between fuel pump module and PDC.

Fuel Injectors

Disconnect fuel injector from wiring harness. Connect ohmmeter between fuel injector terminals. Resistance should be about 10.8-13.2 ohms at 68°F (20°C). If resistance is not as specified, replace fuel injector.

See FUEL PUMP RELAY under MOTORS, RELAYS & SOLENOIDS.

CHECKING IDLE AIR CONTROL MOTOR

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-2 under VERIFICATION TESTS to ensure system is functioning properly.

1. Start engine an allow it to reach normal operating temperature. Using scan tool, actuate Idle Air Control (IAC) motor to 1400 RPM. If engine speed does not increase to 1400 RPM, go to next step. If engine speed increased to 1400 RPM, stop actuation. IAC motor is operating properly this time. Test is complete.
2. Turn ignition off. Disconnect IAC motor connector. IAC motor is located on throttle body. Visually inspect connector for corroded, damaged, pushed-out or miswired terminals. Repair connector and terminals as necessary. If connector and terminals are okay, go to next step.
3. Ensure ignition is off. Disconnect PCM connectors. On Cherokee, PCM is located in engine compartment on left front fender, near radiator support. On Grand Cherokee and Wrangler, PCM is located on firewall in right rear corner of engine compartment. On all models, inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of each wire between IAC motor harness connector and PCM C1 harness connector. See WIRING DIAGRAMS article. (Scheme 7)or (Scheme 8). If each resistance is less than 5 ohms, replace IAC motor. If any resistance is 5 ohms or more, repair open in appropriate wire between IAC motor and PCM.

2.5L & 4.0L

Note. On Wrangler 2.5L, manufacturer indicates engine may be equipped with a Closed Crankcase Ventilation (CCV) system or a Positive Crankcase Ventilation (PCV) system. If engine is equipped with a CCV system, it will not have a PCV valve. For more information on PCV system and CCV system, see EMISSION SYSTEMS & SUB-SYSTEMS in THEORY & OPERATION article. If engine is equipped with a PCV system, go to 4.7L WITH 45RFE TRANSMISSION . If engine is equipped with CCV system, continue with the following procedure.

The following procedure checks throttle body calibrations for correct idle conditions. To perform the following procedure, a Fixed Orifice Adapter (6714) must be used. Procedure should only be used to diagnose the throttle body for conditions that may cause idle problems. Before performing this test, ensure Idle Air Control (IAC) motor is functioning properly. See CHECKING IDLE AIR CONTROL MOTOR .

1. Turn ignition off. Remove air duct and air cleaner resonator from top of throttle body. On 2.5L, disconnect tube from fixed orifice fitting at left front side of valve cover. (Scheme 20) Insert either end of fixed orifice adapter into disconnected tube. (Scheme 19) Go to step 3.
2. On 4.0L, disconnect rear breather tube at intake manifold fitting. (Scheme 21) Allow breather tube to hang disconnected on side of engine. Connect a short piece of rubber hose to either end of fixed orifice adapter. (Scheme 19) Go to next step.
3. On all models, connect scan tool to Data Link Connector (DLC). DLC is located below instrument panel, near steering column. Start engine and allow it to reach normal operation temperature. Turn all accessories off. Using scan tool, perform MINIMUM AIR FLOW test.
4. Scan tool will count down to stabilize idle RPM and display minimum airflow RPM. If idle RPM displayed is not 500-900 RPM, replace throttle body. If idle RPM displayed is 500-900 RPM, minimum airflow is okay. Test is complete.

Scheme 19

4.7L With 45RFE Transmission

1. Turn ignition off. Ensure throttle plate and linkage are not binding. Repair throttle plate and linkage as necessary before continuing. If throttle plate and linkage are okay, go to next step.
2. Start engine and allow it to idle. Check engine, brake booster and vacuum hoses for leaks. Ensure Positive Crankcase Ventilation (PCV) system is functioning properly. Repair vacuum leaks as necessary. If PCV system is okay and no vacuum leaks exist, go to next step.
3. Turn ignition off. Disconnect vacuum hose from PCV valve. Install PCV Adapter (6714) into disconnected vacuum hose in place of PCV valve. PCV adapter is a .185" air metering orifice. Disconnect purge hose from throttle body fitting and cap fitting. Purge hose is located on front of throttle body next to Manifold Absolute Pressure (MAP) sensor. Start engine and allow it to idle. Ensure all accessories are off. Allow engine to reach normal operating temperature. Using scan tool, actuate MIN AIRFLOW. If engine speed is 500-900 RPM, no problem is indicated at this time. Test is complete. If engine speed is not 500-900 RPM, go to next step.
4. Turn ignition off. Remove throttle body. While holding throttle open, spray entire throttle body bore with appropriate cleaner. Using a soft scuff pad, clean throttle body bore and throttle plate. Using compressed air, dry throttle body. Install throttle body. Ensure PCV adapter is still installed and throttle body fitting is capped. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, actuate MIN AIRFLOW. If engine speed is not 500-900 RPM, replace throttle body. If engine speed is 500-900 RPM, no problem is indicated at this time. Test is complete.

TIMING CONTROL SYSTEMS

Ignition timing is electronically controlled by Powertrain Control Module (PCM). Base ignition timing is NOT adjustable with this system. PCM controlled ignition system consists of engine coolant temperature sensor, crankshaft position sensor, distributor (2.5L), camshaft position sensor, ignition coil(s), manifold absolute pressure sensor and throttle position sensor. For ignition coil resistance test, see IGNITION COIL . For sensor testing, see ENGINE SENSORS & SWITCHES for component testing.

IGNITION COIL

IGNITION COIL RESISTANCE - Ohms @ 70-80°F (21-27°C)

CLOSED CRANKCASE VENTILATION SYSTEM

Note. On Wrangler 2.5L, manufacturer indicates engine may be equipped with a Closed Crankcase Ventilation (CCV) system or a Positive Crankcase Ventilation (PCV) system. If engine is equipped with a CCV system, it will not have a PCV valve. For more information on PCV system and CCV system, see EMISSION SYSTEMS & SUB-SYSTEMS in THEORY & OPERATION article. If engine is equipped with a PCV system, go to POSITIVE CRANKCASE VENTILATION . If engine is equipped with CCV system, continue with the following procedure.

1. Closed Crankcase Ventilation (CCV) system is used on both 2.5L and 4.0L engines. CCV system performs same function as a conventional PCV system, but does not use a vacuum controlled PCV valve. CCV system uses a fixed orifice fitting. Ensure locations of fixed orifice fitting and air inlet fitting have not been exchanged.
2. Fixed orifice fitting may be Gray in color and air inlet fitting may be Black in color. On 2.5L, fixed orifice fitting is located on left front side of valve cover and air inlet fitting is located at rear of valve cover. (Scheme 20) On 4.0L, fixed orifice fitting is located at rear of valve cover and air inlet fitting is located at front of valve cover. (Scheme 21)
3. On all models, remove fixed orifice fitting from valve cover and leave tube attached. Start engine and let idle. A hissing noise should be heard from fixed orifice fitting. Also, a strong vacuum should be felt with a finger placed at fitting inlet. If vacuum is not present, remove fitting. If vacuum is now present at tube, replace fitting. Do not attempt to clean fitting. If vacuum is not present at tube, go to next step.
4. Check tube for kinks or obstruction. Clean tube fitting at intake manifold, if necessary. A 1/4" drill may be used (by hand) to dislodge any solid particles. Reinstall fixed orifice fitting and tube. Disconnect air inlet fitting and hose from front of valve cover.
5. Hold a piece of stiff paper loosely over opening in valve cover. Allow engine to idle for one minute. Paper should be drawn against rubber grommet in valve cover by vacuum in crankcase. If vacuum is not present, check tubes for restrictions or obstructions.

Scheme 20

Scheme 21

Checking Evaporative Emission System

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-1 under VERIFICATION TESTS to ensure system is functioning properly.

1. Start engine and allow it to reach normal operating temperature. Engine must be in closed loop to perform this test. Using scan tool, select SYSTEM TESTS, then PURGE VAPORS TEST. Monitor short term adaptive value on scan tool and press "3" to flow. Short term adaptive value should change. If value changes, no problem is indicated at this time. Test is complete. If short term adaptive value does not change, go to next step.
2. Turn ignition off. Inspect vacuum line from purge solenoid to EVAP canister and to fuel tank. On Cherokee, EVAP purge solenoid is mounted on a bracket at right rear of engine compartment. (Scheme 22) EVAP canister is located underneath left side of vehicle near front of rear axle. On Grand Cherokee, purge solenoid and EVAP canister are located in engine compartment, left of brake booster. (Scheme 23) On Wrangler, EVAP purge solenoid and EVAP canister are located on left side of engine compartment. (Scheme 24) On all models, replace vacuum line as necessary. If vacuum line is okay, go to next step.
3. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Using scan tool, review FREEZE FRAME data. Attempt to duplicate condition that caused DTC to set. Visually inspect related connectors and wiring harness for damage. Check for any related technical service bulletins that may apply. Turn ignition on. Using scan tool, actuate EVAP purge solenoid. Wiggle EVAP purge solenoid wiring harness and listen for EVAP purge solenoid to quit actuating. Using scan tool, read DTCs. If GOOD TRIP counter is displayed and displayed count changes to "0", or EVAP purge solenoid quits actuating, repair wiring where wiggling caused EVAP purge solenoid to quit actuating. If EVAP purge solenoid does not stop actuating and GOOD TRIP counter is not displayed or displayed count does not change to "0", no problem is indicated at this time. Test is complete.
4. Inspect line from rollover valve to EVAP canister. Rollover valve is mounted in top of fuel tank, next to fuel pump module. If any fuel is in rollover valve line, replace rollover valve. Rollover valve is not serviced separately. If rollover valve is defective, fuel tank must be replaced. See FUEL TANK under FUEL SYSTEM in REMOVAL, OVERHAUL & INSTALLATION article. If no fuel is in rollover valve hose, go to next step.
5. Remove EVAP purge solenoid. Tap EVAP purge solenoid ports against a clean, solid surface. If foreign material falls out of ports, replace EVAP purge solenoid. If no foreign material falls out of ports, no problem is indicated at this time. Test is complete.

Scheme 22

Scheme 23

Scheme 24

EVAP Canister

On Cherokee, EVAP canister is located underneath left side of vehicle near front of rear axle. On Grand Cherokee, EVAP canister is located in engine compartment, left of brake booster. On Wrangler, EVAP canister is located on left front fender of engine compartment. (Scheme 22), (Scheme 23) or (Scheme 24). On all models, EVAP canister has no moving parts. Check for loose, missing, cracked or broken connections and parts. Repair or replace as necessary. No liquid should be in canister.

4.7L

1. Disconnect hose from Positive Crankcase Ventilation (PCV) valve. PCV valve is located on engine oil filler tube. Rotate PCV valve downward until locating tabs on PCV valve align with slots on filler tube. Nipple on PCV valve should now be pointing downward. Remove PCV valve. Check condition of PCV valve "O" ring and replace as necessary.
2. Reconnect hose to PCV valve. Start engine and allow it to idle. If valve is functioning properly, a hissing sound will be heard as air passes through valve. Place finger over PCV valve inlet. A strong vacuum should be felt at valve inlet. If vacuum is not felt, turn ignition off and go to next step. If vacuum is felt, turn ignition off and go to step 4.
3. Disconnect hose from PCV valve. Remove and shake PCV valve to ensure a metallic clicking noise can be heard, indicating valve is free. If valve is not free, do not attempt to clean PCV valve. Replace valve. If PCV valve is free, check for obstructions or kinks in PCV valve hose. If hose is okay, check for plugged vacuum fitting at rear of intake manifold. Repair vacuum fitting as necessary and go to next step.
4. Reinstall PCV valve. Disconnect fresh air hose from air cleaner resonator on top of engine. (Scheme 25) Start engine and allow it to idle. Hold a piece of stiff paper over fresh air hose opening. After allowing about one minute for crankcase pressure stabilization, paper should be drawn against opening. If paper is held against opening, system is functioning properly. If paper is not held against opening, check hoses/tubes and crankcase breathers for restrictions. Repair PCV system as necessary.

Scheme 25

MISCELLANEOUS CONTROLS

Note. Although some of the controlled devices listed here are not technically engine performance components, they can affect driveability if they malfunction.

Cherokee

1. Turn ignition on. Using scan tool, actuate radiator fan relay. Check radiator fan operation. If radiator fan cycles on and off, go to next step. If radiator fan does not cycle on and off, go to step 3.
2. Using scan tool, check for Diagnostic Trouble Codes (DTC). If any DTCs are present, perform appropriate diagnostic test. See DTC MESSAGES & CODES table under DIAGNOSTIC TROUBLE CODE DEFINITIONS in appropriate SELF-DIAGNOSTICS article. If no DTCs are present, no problem is indicated at this time. Test is complete.
3. Using scan tool, check for Diagnostic Trouble Codes (DTC). If no DTCs are present, stop radiator fan relay activation and go to next step. If any DTCs are present, perform appropriate diagnostic test. See DTC MESSAGES & CODES table under DIAGNOSTIC TROUBLE CODE DEFINITIONS in appropriate SELF-DIAGNOSTICS article.
4. Turn ignition off. Disconnect radiator fan motor connector. Inspect connector for damaged pins, corrosion and loose terminals. Repair connector as necessary. If connector terminals are okay, turn ignition on. Using scan tool, actuate radiator fan relay. Using a test light connected to ground, probe Light Blue wire at radiator fan motor harness connector. If test light flashes on and off, stop radiator fan relay activation and go to next step. If test light does not flash on and off, go to step 7.
5. Turn ignition off. Measure resistance between ground and Black wire at radiator fan motor harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Black wire between radiator fan motor and ground. Ground connection is located in left front of engine compartment, near Powertrain Control Module (PCM).
6. At this time, radiator fan motor is assumed to be defective. Replace radiator fan motor.
7. Turn ignition off. Using a test light connected to ground, probe terminal D10 (Light Green/Red wire) at radiator fan relay socket in Power Distribution Center (PDC). PDC is located in right side of engine compartment, next to battery. (Scheme 15) If test light illuminates brightly, go to next step. If test light does not illuminate brightly, check for open in Light Green/Red wire between radiator fan relay and PDC. Also check fuse No. 5 (40-amp) in PDC. See WIRING DIAGRAMS article. Repair wiring as necessary.
8. Turn ignition off. Measure resistance of Light Blue wire between radiator fan motor harness connector and terminal D14 at radiator fan relay socket in PDC. (Scheme 15) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open Light Blue wire between radiator fan relay and radiator fan motor.
9. At this time, radiator fan relay is assumed to be defective. Replace radiator fan relay.

Grand Cherokee (4.0L)

Note. Grand Cherokee 4.7L is equipped with a hydraulic cooling module consisting of a hydraulic fan control solenoid, hydraulic fan drive assembly and radiator fan blade. For testing, see DTC P1499: HYDRAULIC FAN SOLENOID under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - GRAND CHEROKEE article.

1. Turn ignition on. Using scan tool, actuate radiator fan relay. Check radiator fan operation. If radiator fan cycles on and off, no problem is indicated at this time. Test is complete. If radiator fan does not cycle on and off, go to next step.
2. Ensure radiator fan relay is still actuated. Using a test light connected to ground, backprobe Dark Green wire at radiator fan motor harness connector. If test link flashes on and off, go to next step. If test light does not flash on and off, go to step 5 .
3. Turn ignition off. Measure resistance between ground and Black/Pink wire at radiator fan motor harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Black/Pink wire between radiator fan motor and ground connection.
4. At this time, radiator fan motor is assumed to be defective. Replace radiator fan motor.
5. Turn ignition off. Disconnect radiator fan relay connector. Relay is located in right front corner of engine compartment. Measure voltage between ground and Gray wire at radiator fan relay connector. If battery voltage is present, go to next step. If battery voltage is not present, repair open power circuit (Gray wire) to radiator fan relay. Also check fuse No. 10 (40-amp) in Power Distribution Center (PDC). PDC is located in right side of engine compartment, next to battery.
6. Measure resistance of Dark Green wire between radiator fan relay and radiator fan motor. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Dark Green wire.
7. At this time, radiator fan relay is assumed to be defective. Replace radiator fan relay.

AUTOMATIC TRANSMISSION

For automatic transmission diagnostic information, see appropriate ELECTRONIC CONTROLS article in AUTOMATIC TRANSMISSIONS.