Exterior lighting: Diagnosis

The exterior lighting must be set to the "diagnostic mode" as a condition for carrying out various diagnosis orders.

For example, the "diagnostic mode" is required for the following diagnosis orders:

• Reading out relevant bus signals while the vehicle is stationary
  • Speed
  • Yaw rate
  • Steering angle
• Analysis of switch-on conditions
  • Status of rain-light-solar-condensation sensor.
  • Status of high-beam assistant
  • Status of light switch

When expected bus signals are not received and when they are classified as implausible a corresponding diagnostic trouble code (DTC) is logged in the footwell module (FRM).

The types of faults are stored in the headlight driver module. The footwell module (FRM) provides access to the headlight driver module.