Currently known fault patterns of the trailer module AHM3

• The lighting on the trailer does not work although all the trailer lights and the wiring have no faults. 
  • Description 

    The customer complains that the trailer lighting is not functioning. Check Control messages for the lighting also appear. No fault codes are stored in the fault memory.

  • Cause 

The trailer of the customer is equipped with a lighting system that has a higher power requirement. The trailer module detects this excess current at the outputs for the lighting. This means that the trailer module disables the corresponding outputs.

Two variants of this problem currently occur.

• Trailers that are equipped with an additional stop light and no other changes/extensions have been made to the lighting system.

  This affects vehicles with production date before 03/2006. These trailer modules must be programmed with the current DVD. The problem is then rectified.

• All other trailers with extended lighting (e.g.: additional side marker lights, side repeaters, raised lighting etc.) To use these trailers, the trailer module must be replaced by a more powerful AHM3+. This trailer module is specially designed for trailers that have a higher electrical power requirement. To this end, a second supply lead is to be routed to the trailer module. The newly installed trailer module is to be coded. This affects vehicles with production date before 09/2006.

  Procedure 

  • Remove the trailer module.
  • Fit a new AHM3+ (see repair instructions "Removing and fitting the trailer module").
  • Route a second supply lead to the trailer module. Part number 61 129 130 258 (E90, E91, E92, E93, E87); 61 129 128 792 (E60, E61)
  • The supply lead is to be pinned into chamber 2 of X609.B on the trailer module side.
  • Subsequently, the supply lead must be routed to the front distribution box on the wiring harness and pinned in as follows.

    E90, E91, E92, E93: X11006 chamber 3E60, E61: X11004 chamber 3E65, E66: X4884 chamber 5

  • Fit a 30 Ampere fuse to the supply lead. Then the newly installed trailer module is to be coded.