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Home >> Jeep >> 2021 >> Gladiator Mojave, Part Time T/Case Control, Automatic Trans >> Repair and Diagnosis (Single Page) >> Accessories & Equipment >> Communication Devices >> Body Control Module (BCM) - DTCS B16AF-11 To B1792-11 >> DTC Troubleshooting >> B178E-11-Headlamp Switch Input-Circuit Short To Ground >> Diagnostic Test

Diagnostic Test

  1. READ AND RECORD DTCS AND ENVIRONMENTAL DATA 
    NOTE:

    CLEARING THE DTC AFTER MAKING A REPAIR - Perform after wiring repair or module replacement:

    Before the DTC can be erased from the Body Control Module (BCM), the BCM must detect an ignition ON/OFF/ON cycle, making sure the Power Accessory Delay (PAD) is deactivated after the ignition transitions to OFF, along with the normal operation of the system associated with this DTC.

    1. Turn the ignition on.
    2. With the scan tool, read DTCs in all Electronic Control Units (ECUs) and record on the repair order.
    3. With the scan tool, run a vehicle Scan Report, or record the Environmental Data related to the DTCs.
    4. With the scan tool, read Body Control Module (BCM) DTCs.

    Is the DTC Active?

    Yes 

    • Go To  2

    No 

    • Perform the appropriate INTERMITTENT CONDITION diagnostic procedure. Refer to STANDARD PROCEDURE .
  2. CHECK THE HEADLAMP SWITCH FOR AN INTERNAL SHORT 
    NOTE:

    Additional DTCs may set when the harness connector is disconnected and the ignition is positioned on. After all repairs are completed, make sure to erase any additional DTCs that may have set.

    1. Turn the ignition off.
    2. Disconnect the Headlamp Switch harness connector.
    3. Turn the ignition on.
    4. With the scan tool, read BCM DTCs.

      Is the DTC Active?

      Yes 

      • Go To  3

      No 

  3. DISCONNECT THE BCM HARNESS CONNECTOR(S) AND CHECK THE (L307) HEADLAMP SWITCH MUX CIRCUIT FOR A SHORT TO GROUND 
    1. The ignition must be off when checking a circuit for continuity to ground.
    2. Disconnect all Electronic Control Unit (ECU) harness connectors containing the circuit being tested. Note:  Use the wiring diagram as a guide to follow the path of the circuit.
    3. Connect the negative lead of the DVOM to a known good ground.
    4. Connect the positive lead of the DVOM to the circuit being tested at the ECU or component harness connector and check for continuity between the circuit and ground.
    NOTE:

    When probing a circuit at any harness connector, always use an appropriate probing tool to prevent any possible damage to the harness connector terminals.

    NOTE:

    There should be no continuity between ground and the circuit being tested.

    Is there continuity between ground and the circuit being tested?

    Yes 

    • Repair the circuit for a short to ground. Use the wiring diagram as a guide to trace the circuit and look for any in-line connectors to help isolate the location of the short.
    • Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .

    No 

    • Go To  4
  4. CHECK THE (L307) HEADLAMP SWITCH MUX CIRCUIT FOR A SHORT TO THE (L900) HEADLAMP SWITCH MUX RETURN CIRCUIT 
    1. The ignition must be off when performing a resistance check to find a short between circuits.
    2. Connect one lead of the DVOM to the circuit being tested at the component harness connector.
    3. With the other lead of the DVOM probe the other circuit at the component harness connector.
    NOTE:

    When probing a circuit at an Electronic Control Unit (ECU) harness connector, always use an appropriate back probing tool to prevent any possible damage to the ECU terminals.

    NOTE:

    With the circuit isolated there should be no continuity between the circuit being tested and any other circuit.

    Is there continuity between the circuit being tested and the other circuit?

    Yes 

    • Repair the short between the circuits. Use the wiring diagram as a guide to trace the circuits and look for any in-line connectors to help isolate the location of the short.
    • Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .

    No 

    • Go To  5
  5. DISCONNECT RELATED MODULE HARNESS CONNECTIONS AND INSPECT FOR PROBLEMS 
    1. Disconnect all BCM harness connectors.
    2. Disconnect all related in-line harness connections (if equipped).
    3. Disconnect the related component harness connectors.
    4. Inspect harness connectors, component connectors, and all male and female terminals for the following conditions:
      • Proper connector installation.
      • Damaged connector locks.
      • Corrosion.
      • Other signs of water intrusion.
      • Weather seal damage (if equipped).
      • Bent terminals.
      • Overheating due to a poor connection (terminal may be discolored due to excessive current draw).
      • Terminals that have been pushed back into the connector cavity.
      • Perform a terminal drag test on each connector terminal to verify proper terminal tension.

      Repair any conditions that are found.

    5. Connect all BCM harness connectors. Be certain that all harness connectors are fully seated and the connector locks are fully engaged.
    6. Connect all in-line harness connectors (if equipped). Be certain that all connectors are fully seated and the connector locks are fully engaged.
    7. Connect all related component harness connectors. Be certain that all connectors are fully seated and the connector locks are fully engaged.
    8. With the scan tool, erase DTCs.
    9. Using the recorded Environmental Data, along with the When Monitored and Set Conditions above, operate the vehicle in the conditions that set the DTC.
    10. With the scan tool, read BCM DTCs.

      Did the DTC return?

      Yes 

      No 

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