Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Circuit/System Testing
2018 Chevrolet Traverse LS, 4WDSECTION Circuit/System Testing
- Verify that no other DTCs are set except for DTC P156D.
- If any other DTCs are set
Refer to Diagnostic Trouble Code (DTC) List - Vehicle .
- Go to next step: If only DTC P156D is set
- If any other DTCs are set
- Replace the T19 Power Supply Transformer.
- Verify the DTC does not set while operating the vehicle within the Conditions for Running the DTC.
- If DTC sets
Replace the K20 Engine Control Module.
- Go to next step: If DTC does not set
- If DTC sets
- All OK.
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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.