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.
Normal Operation and Fault Conditions
The Hill Descent Control switch is used to activate and deactivate the Hill Descent Control system. When the driver presses the Hill Descent Control switch, the IPC receives a ground signal from the switch and illuminates the Hill Descent Control indicator. The IPC sends a Hill Descent Control switch message to the GWM over the HS-CAN 3 and the GWM relays this message to the ABS module over the HS-CAN 2. The ABS module takes the necessary action depending on the switch inputs and Hill Descent Control message.
The Hill Descent Control switch is part of the center stack switch assembly.
| DTC | Description | Fault Setting Conditions |
|---|---|---|
| C1000:86 | Hill Descent Control (HDC) Function: Signal Invalid | This DTC sets if the Hill Descent Control switch message sent from the IPC indicates the switch has been pressed for longer than 30 seconds. This can be caused by a short to ground on the Hill Descent Control circuit or if there is an internal failure of the Hill Descent Control switch. |
| U0401:86 | Invalid Data Received From ECM/PCM "A": Signal Invalid | This DTC sets if the Hill Descent Control switch message from the IPC indicates the switch is stuck or held in place for longer than 30 seconds. This can be caused by a short to ground on the Hill Descent Control circuit or if there is an internal failure of the Hill Descent Control switch. |
NO RELATED
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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.