System functions

The trailer module activates the trailer lighting circuits: brake light, side lights, parking light, turn indicator, hazard warning flashers, crash alarm hazard warning flashers, DWA alarm flashers, rear fog light and reversing light

The trailer module detects a trailer as connected when at least two loads (cold measurement) are detected at the lighting outputs. The trailer module then reports the status "Trailer connected". This status report is implemented in the towing vehicle in a number of control units. For example, the Park Distance Control is disabled at the rear.

In vehicles with a production date up to 2006, the reversing light and the rear fog light of the towing vehicle are deactivated during trailer towing.

In newer vehicles, the reversing light is no longer deactivated. If the rear fog light on the trailer fails, this switches over to the rear fog light of the towing vehicle.

The fully automatic trailer tow hitch is an element of optional equipment S03AC (trailer tow hitch). The system has its own functional description.