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Home >> GMC >> 2024 >> Sierra EV >> Repair and Diagnosis >> Body & Frame >> Towing Systems >> TRAILERING Systems >> Diagnostic Information and Procedures >> Trailer Detection Malfunction >> Circuit/System Verification

Circuit/System Verification

With Available Trailer

    NOTE:
    • This test should be used when the customer's trailer is available to use while performing diagnostics.
    • A circuit fault or damage with the customer supplied equipment is not diagnosed or supported by GM service information.
  1. Inspect the X88B Tow Vehicle Electrical Receptacle for corrosion and/or visible damage.
    • If corrosion and/or visible damage exists 

      Repair or replace as necessary

    • Go to next step: If no condition exists. 
  2. Connect the trailer wiring harness to the X88B Tow Vehicle Electrical Receptacle.
  3. Ignition ON/Vehicle in Service Mode.
  4. Verify there are no trailer related DTCs set.
    • Go to next step: If no trailer related DTCs are set. 
  5. Verify the scan tool Trailer Connection Status parameter is Connected in the K68 Trailer Lamp Control Module.
    • If the parameter status is Not Connected. 
    1. Disconnect the customer's trailer.
    2. Connect the EL-52641  . If the EL-52641  is not available, connect a simulated trailer, such as a trailer load box tool or a custom trailer simulator with complete and functioning trailer lights. Refer to: Trailering Description and Operation  for more information on creating a simulated trailer tool.
    3. Verify the scan tool Trailer Connection Status parameter is Connected.
      • Go to next step: If the parameter is Connected.
    4. An issue exists with the customer's trailer that is preventing it from being detected by the K68 Trailer Lamp Control Module. The Trailer Lamp Control Module detects a trailer based on the lighting load. Some LED trailer lamps do not draw enough current may not be detected by the Trailer Lamp Control Module. Other causes my be a generally poor condition of the customer's trailer wiring or a poor connection at the trailer connector. Discuss with the customer these scenarios and advise to correct the trailer wiring, connector, update the trailer lights or add load resistors to the lighting circuits of the trailer.
    • Go to next step: If the parameter status is Connected. 
  6. All OK.

Without Available Trailer

    NOTE:

    This test should be used when the customer's trailer is not available to use while performing diagnostics.

  1. Inspect the X88B Tow Vehicle Electrical Receptacle for corrosion and/or visible damage.
    • If corrosion and/or visible damage exists 

      Repair or replace as necessary

    • Go to next step: If no condition exists. 
  2. Ignition ON/Vehicle in Service Mode.
  3. Verify there are no trailer related DTCs set.
    • Go to next step: If no trailer related DTCs are set. 
  4. Connect the EL-52641  Trailer Presence Simulator Tool. If the EL-52641  Trailer Presence Simulator Tool is not available, connect a simulated trailer, such as a trailer load box tool or a custom trailer simulator with complete and functioning trailer lights. Refer to: Trailering Description and Operation  for more information on creating a simulated trailer tool.
  5. Verify the scan tool Trailer Connection Status parameter shows Connected.
    • Go to next step: If the parameter is Connected. 
  6. There is no issue with trailer detection at this time. The K68 Trailer Lamp Control Module detects a trailer based on the lighting load. Some LED trailer lamps do not draw enough current may not be detected by the K68 Trailer Lamp Control Module. Other causes my be a generally poor condition of the customer's trailer wiring or a poor connection at the trailer connector. Discuss with the customer these scenarios and advise to correct the trailer wiring, connector, update the trailer lights, or add load resistors to the lighting circuits of the trailer.
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