Circuit/System Verification
WARNING: This page is about a different car, the 2023 GMC Sierra 3500 HD and 2023 GMC Sierra 2500 HD. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition - On/Vehicle - In Service Mode
- Verify there are no DTCs set related to the following component/system: S126 Drive Mode Select Switch & K69 Transfer Case Control Module
- If any DTC is set
- Go to next step: If no DTC is set
- Perform the scan tool control function: Transfer Case Range - 2WD/4WD/AWD Automatic/4WD High/Locked/4WD Low
Verify operating the controls yields the expected results.
- If the function is NOT executed as expected
Refer to: Symptoms - Transfer Case
- Go to next step: If the function is executed as expected
- If the function is NOT executed as expected
- Operate the component: S126 Drive Mode Select Switch - 2WD/4WD/AWD Automatic/4WD High/Locked/4WD Low
Verify operating the controls yields the expected results.
- If the function is NOT executed as expected
Refer to: DTC P159F, P15A0, or P15A1
- Go to next step: If the function is executed as expected
- If the function is NOT executed as expected
- All OK.