HDC Speed Control

Hill Descent Control (HDC)

The HDC system automatically detects downhill driving and keeps the speed constant. The driver can vary this given hill descent speed as follows:
- Light braking using the brake pedal
- Light acceleration using the accelerator pedal module
- Pressing the speed keys of the multi-function steering wheel (MFL)

If the fault 'HDC cruise control' is stored, the HDC speed can no longer be controlled via the multi-function steering wheel. However, adaptive control of the HDC speed is still possible using the accelerator pedal module and/or brake pedal.

Possible cause(s) of fault:
- Cable between MFL and DME/DDE defective
- Speed keys of the MFL defective
- DME/DDE defective

Storage condition(s):
The DSC receives a message from the DME/DDE to the effect that the multi-function steering wheel is not transmitting the status of the speed keys correctly or not transmitting it at all.

Troubleshooting procedure:
Fault elimination is in the suggested test modules via the corresponding test plan of the DME/DDE.