Diagnostic Test

2010 Jeep Grand Cherokee Limited, 5.7 T, 4WDSECTION Diagnostic Test
  1. CHECK FOR ACTIVE DTC 
    1. With the scan tool, read the active DTCs.
    2. Cycle the ignition switch from off to on, leaving the ignition on for a minimum of 90 seconds.
    3. With the scan tool, read the active DTCs.

      Does the scan tool display this DTC as active?

      Yes 

      • Go to step  2

      No 

  2. RUN/ACCESSORY DELAY RELAY 
    1. Turn the ignition off.
    2. Install a substitute relay in place of the original Run/Accessory Delay Relay.
    3. Cycle the ignition switch from off to on, leaving the ignition on for a minimum of 90 seconds.
    4. With the scan tool, read the active FCM DTCs.

      Does the scan tool display this DTC as active?

      Yes 

      • Go to step  3

      No 

  3. (P305) ACCESSORY DELAY RELAY CONTROL CIRCUIT OPEN 
    Fig 1: Checking Accessory Delay Relay Control Circuit For Open
    GC0120149Courtesy of CHRYSLER LLC
    1. Turn the ignition off.
    2. Remove the FCM from the Integrated Power Module.
    3. Remove the Run/Accessory Delay Relay from the Junction Block.
    4. Measure the resistance of the (P305) Accessory Delay Relay Control circuit from the Front Control Module IPM connector to the Relay connector.

      Is the resistance below 10.0 ohms?

      Yes 

      • Go to step  4

      No 

  4. (P305) ACCESSORY DELAY RELAY CONTROL CIRCUIT SHORTED TO GROUND 
    Fig 2: Checking Accessory Delay Relay Control Circuit For Short To Ground
    GC0106204Courtesy of CHRYSLER LLC
    1. Measure the resistance between ground and the (P305) Accessory Delay Relay Control circuit at the relay cavity (85).

      Is the resistance below 100.0 ohms?

      Yes 

      No 

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • You smell fuel, burning insulation, or see smoke.
  • Brakes feel soft, pull hard to one side, or make grinding noises.
  • The engine overheats, stalls repeatedly, or misfires under load.
  • You are missing required tools, torque specs, or safe lifting equipment.
  • You are not confident in the next step or safety outcome.