Circuit/System Verification

WARNING: This page is about a different car, the 2017 GMC Yukon XL, 2017 GMC Yukon, 2017 Chevrolet Tahoe, and 2017 Chevrolet Suburban. However, it is still accessible from the selected car via links, so may be relevant.

Verify DTC C0321 in NOT set.
- If DTC C0321 is set
  diagnose it first. Refer to DTC C0321 or C0326 .
- If DTC C0321 is NOT set
Verify that all of the following scan tool parameters display OK.
- Range Actuator Control Circuit High Voltage Test Status
- Range Actuator Control Circuit Low Voltage Test Status
- Range Actuator Control Circuit Open Voltage Test Status
- Range Actuator Control Circuit Shorted Test Status
- If any of the parameters do NOT display OK
  Refer to Circuit/System Testing.
- If all of the parameters display OK
Verify that for all range selections of the S77 transfer case shift control switch, the Range Actuator Current parameter increases or decreases during the shift and then returns to 0.0 A after shifting.
- If the Range Actuator Current parameter does NOT perform as described
  Refer to Circuit/System Testing.
- If the Range Actuator Current parameter DOES perform as described
Verify DTC C0306 or C0381 is only set as a history DTC.
- If C0306 or C0381 is set as current
  Refer to Circuit/System Testing.
- If C0306 or C0381 is only set as history

NOTE:

After inspection, apply Nyogel lubricant 760G to each connector terminal. Ensure each connector and CPA is correctly seated.

Visually inspect each connector terminal of the K69 transfer case control module X3 connector and the A16 transfer case motor connector for damage or corrosion. Repair as necessary.
Clear DTC C0306 or C0381 from history.
Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data. The DTC should not set.
- If DTC C0306 or C0381 sets
  Refer to Circuit/System Testing.
- If DTC C0306 or C0381 does not set
All OK.