Diagnostic Test

2023 Jeep Grand Cherokee Limited, AWDSECTION Diagnostic Test
  1. READ AND RECORD DTCS AND ENVIRONMENTAL DATA - ERASE DTCS AND CHECK FOR DTC TO RETURN 
    1. With the scan tool, read DTCs in all Electronic Control Units (ECUs) and record on the repair order.
    2. With the scan tool, run a vehicle Scan Report, or record the Environmental Data related to the DTCs.
    3. With the scan tool, erase all DTCs.
    4. Turn the ignition off for a minimum of 10.0 seconds.
    5. Start the Engine.
    6. Turn the Right Rear Heated Seat on.
    7. Using the recorded Environmental Data and the When Monitored Conditions, operate the vehicle in the conditions that set the DTC.
    8. With the scan tool, read CRSM DTCs.

    Is the same DTC active?

    Yes 

    • Go To  2

    No 

  2. ISOLATE AND LOAD TEST THE (P871) POWER SUPPLY CIRCUIT TO CHECK FOR AN OPEN OR HIGH RESISTANCE 
    NOTE:

    DIAGNOSE AND REPAIR ALL LIN BUS RELATED DTC'S BEFORE PERFORMING THIS TEST PROCEDURE 

    The ignition must be off when performing a load test on a circuit.

    1. Isolate the circuit by disconnecting the Electronic Control Unit (ECU) and every component harness connector containing the circuit being tested.
    2. Connect the positive lead of the load test tool to the positive side of the Battery (A). Note:  . Refer to the diagram below.
    3. Using an approved back probe tool, connect the negative lead of the load test tool to the circuit being tested at the one of the component harness connectors (B).
    4. Using an approved back probe tool and a fused jumper wire, connect the circuit being tested to the negative side of the Battery or a known good ground at the other component harness connector (C and D).
    5. The bulb on the load test tool should be illuminated and bright if there is no resistance in the circuit.
    NOTE:

    Note: Why load test a circuit?  A load test is used to determine if a circuit is capable of carrying the amperage needed to perform properly. The 3156 bulb in the load tool illustrated, is a simple but effective method of testing circuit functionality. A 3156 Bulb has approximately 6.0 Ohms of resistance when the bulb is powered  and draws approximately 2.0 amps of current. Read the CIRCUIT LOAD TESTING PROCEDURE for information on building a simple load test tool and for additional load testing information and alternative methods of load testing or voltage drop. Refer to CIRCUIT LOAD TESTING PROCEDURES .

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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.