Circuit/System Testing

2011 GMC Yukon Base, 5.3 0, RWDSECTION Circuit/System Testing
  1. Ignition OFF, disconnect the harness connector at the B71R liftgate object sensor - right.
  2. Test for less than 10 Ξ© between the low reference circuit terminal B and ground.
    • If greater than the specified range, test the low reference circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K39 liftgate module.
  3. Disconnect the harness connector at the B71L liftgate object sensor - left.
  4. Ignition ON, test for 4.75-5.25 V between the signal circuit terminal A and ground.
    • If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K39 liftgate module.
    • If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K39 liftgate module.
  5. Test of infinite resistance between the signal circuit terminal B and ground.
    • If not the specified value, test the signal circuit for a short to ground.
  6. Test for less than 10 Ξ© between the signal circuit terminal A at the B71R liftgate object sensor - right and the signal circuit terminal B at the B71L liftgate object sensor - left.
    • If greater than the specified range, test the signal circuit for an open/high resistance.
  7. If all circuits test normal, test or replace the appropriate B71 liftgate object sensor.
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When to See a Mechanic

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

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