2010 GMC Terrain SLT, 3.0 Y, FWDFACTORY OEM SERVICE PROCEDURE

Circuit/System Testing

NOTE: Use the schematic to determine which control modules are on the BCM communications enable circuit 23, X4.
  1. Ignition OFF, disconnect the harness connector at the most easily accessible control module on the BCM communications enable circuit.
  2. Ignition ON, retest for current DTCs. DTC U2099 should remain current.
    • If the DTC becomes history, replace the control module.
  3. With the prior control modules disconnected, repeat steps 1 and 2 for each control module on the circuit except the BCM.
  4. Ignition OFF, disconnect the X 4 harness connector at the K9 BCM.
  5. Test for infinite resistance between the serial data communication enable circuit terminal 23 and ground.
    • If less than infinite resistance, repair the enable circuit for a short to ground.
  6. If all circuits tests normal, replace the K9 BCM.
Factory Service Tools

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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.

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