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Grand Cherokee

  1. Turn ignition off. Check Power Distribution Center (PDC) and junction block for blown fuses. PDC is located in right side of engine compartment, next to battery. Junction block is located under left side of instrument panel. Replace blown fuses and check related circuits for short to ground. If fuses are okay, go to next step.
  2. Turn ignition on, with engine off. Using scan tool, read SECONDARY INDICATORS while cranking engine. If any DTCs are displayed, perform appropriate test for specified DTC(s). See DTC MESSAGES & CODES table under DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - GRAND CHEROKEE article. If no DTCs are displayed, go to next step.
  3. Check if battery is fully charged and in good condition. A defective battery may produce invalid test results. If battery is low, recharge battery then attempt to start vehicle by cranking engine for 15 seconds, 3 consecutive times. This will allow DTCs to set that may have been erased due to a dead battery. If PCM does not communicate with scan tool, perform appropriate system test. See COMMUNICATIONS under SYSTEM TESTS in BODY CONTROL MODULES - GRAND CHEROKEE article in ACCESSORIES & EQUIPMENT. If PCM communicates with scan tool, check for DTCs. If any DTCs are displayed, perform appropriate test for specified DTC(s). See DTC MESSAGES & CODES table under DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - GRAND CHEROKEE article. If no DTCs are displayed, go to next step.
  4. Ensure ignition is on, with engine off. Using scan tool in inputs/outputs mode, read VEH THEFT SECURITY status. If scan tool displays FUEL ON, go to next step. If scan tool does not display FUEL ON, diagnose vehicle theft security system by symptom. See VEHICLE THEFT SECURITY SYSTEM under SYSTEM TESTS in BODY CONTROL MODULES - GRAND CHEROKEE article in ACCESSORIES & EQUIPMENT.
  5. Using scan tool, actuate Auto Shutdown (ASD) fuel system test. Using a mechanic's stethoscope, listen for fuel pump operation at fuel tank. If fuel pump operation cannot be heard, stop ASD fuel system actuation and go to step  9. If fuel pump operation can be heard, stop ASD fuel system actuation and go to next step.
  6. Ensure ignition is on, with engine off. Using scan tool in inputs/outputs mode, read CURRENT SYNC STATE while cranking engine. If scan tool does not display OUT OF SYNC, go to next step. If scan tool displays OUT OF SYNC, check Crankshaft Position (CKP) sensor signal circuit for short to Camshaft Position (CMP) sensor signal circuit. See WIRING DIAGRAMS article. Repair wiring as necessary. If wiring is okay, check for incorrect valve timing. See appropriate article in ENGINES. Adjust valve timing as necessary.
    7. WARNING: High fuel pressure may be present in fuel lines. Open fuel system with caution. See FUEL SYSTEM PRESSURE RELEASE .
  7. Turn engine off. Release fuel pressure. Connect fuel pressure gauge to fuel rail. Turn ignition on, with engine off. Using scan tool, actuate ASD fuel system test. Allow fuel pressure gauge to stabilize. Stop ASD fuel system activation. Fuel pressure should be 44.2-54.2 psi (3.23-3.96 kg/cm2 ). 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. If fuel return line is okay, replace fuel filter/pressure regulator. Fuel filter/pressure regulator is located in front of fuel tank, above rear axle. See Figure. If fuel pressure is as specified, fuel system is okay. Diagnose by symptom. See TROUBLE SHOOTING - NO CODES article.
    8. WARNING: High fuel pressure may be present in fuel lines. Open fuel system with caution. See FUEL SYSTEM PRESSURE RELEASE .
  8. Turn ignition off. Check and repair restricted fuel supply line between fuel rail and fuel pump module. Fuel pump module is located in fuel tank. If fuel line is okay, release fuel pressure. Raise and support vehicle. Disconnect fuel pressure line from fuel filter/pressure regulator. 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/cm2 ). 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, release fuel pressure and replace fuel pump module.
  9. Turn ignition off. Disconnect fuel pump module connector. Fuel pump module is located in fuel tank. Inspect connector for damaged pins, corrosion and loose terminals. Repair connector as necessary. If connector terminals are okay, measure resistance between ground and Black wire at fuel pump module connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Black wire.
  10. Turn ignition on, with engine off. Using scan tool, actuate ASD fuel system test. Using a 12-volt test light connected to ground, probe Dark Green/Black wire at fuel pump module connector. If test light illuminates brightly, go to next step. If test light does not illuminate brightly, go to step  12.
  11. At this time, fuel pump module is assumed to be defective. Replace fuel pump module.
  12. Turn ignition off. Ensure fuel pump module is still disconnected. Remove fuel pump relay from PDC. See Figure. Inspect connector for damaged pins, corrosion and loose terminals. Repair connector as necessary. If connector terminals are okay, measure resistance of Dark Green/Black wire between fuel pump module connector and terminal No. 87 at fuel pump relay connector socket in PDC. See Figure. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Dark Green/Black wire.
  13. Using a 12-volt test light connected to ground, probe terminal No. 30 at fuel pump relay socket in PDC. See Figure. If test light illuminates brightly, go to next step. If test light does not illuminate brightly, check for open or high resistance in Violet/White wire between fuel pump relay and PDC. Also, check fuse No. 24 (20-amp) in PDC. Repair wiring as necessary.
  14. At this time, fuel pump relay is assumed to be defective. Replace fuel pump relay.
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