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Home >> GMC >> 2018 >> Acadia Denali, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 198 (Manual Transmission - TREMEC 6-Speed (M3L Mg9)) >> Diagnostic Information and Procedures >> DTC P18C6 or P18C7: Gear Position Sensor >> Circuit/System Verification

Circuit/System Verification

WARNING: This page is about a different car, the 2017 Cadillac ATS. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition ON.
  2. Verify DTC P0651 is not set.
    • If the DTC is not set 
  3. Verify the scan tool Gate Select Position Sensor parameter displays the following duty cycle as the gear shift lever is moved through each gear position:
    • 73-87% duty cycle for Gear 1, Gear 3, Gear 5, and Reverse Gear
    • 48-60% duty cycle for Neutral 3-4 Gate
    • 25-34% duty cycle for Gear 2, Gear 4, and Gear 6
    • If the Gate Select Position Sensor parameter is not within the specified range 

      Refer to Circuit/System Testing.

    • If the Gate Select Position Sensor parameter is within the specified range 
  4. Operate the vehicle within the conditions for running the DTC to verify the DTC does not set. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.
    • If the DTC sets 

      Refer to Circuit/System Testing.

    • If the DTC does not set 
  5. All OK.