Circuit/System Testing

2016 GMC Sierra 3500 HD SLE, 4D Cab Chassis, 6.6L Eng VIN 8, 4WDSECTION Circuit/System Testing
  1. Ignition OFF, disconnect the harness connector at the S48A Multifunction Switch - Instrument Panel, ignition ON.
  2. Verify a test lamp illuminates between the control circuit terminal 2 and ground.
    • If the test lamp does not illuminate 
    1. Ignition OFF, disconnect the harness connector at the K9 Body Control Module.
    2. Test for less than 2 Ω in the control circuit end to end.
    • If the test lamp illuminates 
  3. Ignition OFF, connect the harness connector at the S48A Multifunction Switch - Instrument Panel. Disconnect the X1 harness connector at the K41 Front and Rear Parking Assist Control Module.
  4. Verify the parking assist switch indicator is not illuminated.
    • If the parking assist switch indicator is illuminated 
    1. Ignition OFF, disconnect the harness connector at the S48A Multifunction Switch - Instrument Panel.
    2. Test for infinite resistance between the S48A Multifunction Switch - Instrument Panel control circuit terminal 6 and ground.
      • If less than infinite resistance, repair the short to ground in the circuit.
      • If infinite resistance, replace the S48A Multifunction Switch - Instrument Panel.
    • If the parking assist switch indicator is not illuminated 
  5. Connect a 3 A fused jumper wire between the control circuit terminal 3 and ground.
  6. Verify the parking assist switch indicator is illuminated.
    • If the parking assist switch indicator is not illuminated 
    1. Ignition OFF, disconnect the harness connector at the S48A Multifunction Switch - Instrument Panel.
    2. Test for less than 1 V between the control circuit and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V
    3. Ignition OFF.
    4. Test for less than 2 Ω in the control circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the S48A Multifunction Switch - Instrument Panel.
    • If the parking assist switch indicator is illuminated 
  7. Replace the K41 Front and Rear Parking Assist Control Module.
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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.