669655 Eliminating Symptoms In Body Interior: Replacing Trailer Control Unit (Message In Instrument Cluster: Trailer Illuminati
WM 669655 Eliminating symptoms in body interior: Replacing trailer control unit (message in instrument cluster: trailer illumination defective)
General information
Symptom
Error message in instrument cluster "Trailer illumination defective".
Causes and remedial action
Cause
If a trailer equipped with illumination that entirely comprises LED s (light emitting diodes) is attached to the vehicle, the error message "Trailer illumination defective " may be output in the instrument cluster because of the low power consumption of the LEDs.
Remedy
If a complaint is made that the error message is output even though the trailer illumination is working , the trailer control unit can be replaced.
Tools and materials
Materials
Information
Vehicle equipped with "alarm system":
The alarm function cannot be triggered when pulling off the trailer connector if the trailer illumination is entirely made of up LED technology.
Please pass this information on to your customers.
Preliminary work
Remove side trim panel on the right for rear luggage compartment. => 700319 Removing and installing side trim panel for rear luggage compartment - "Removing" section.
Installing control unit
1. Insert control unit into the holder -arrow A- and screw in the fastening screw -arrow 1-.
Tighten control unit and connect plug
2. Position and push on both plugs -arrows B- until the locking tabs -arrows C- are felt to engage.
Tighten control unit and connect plug
Coding control unit
Extracting and changing coding
Information
- After the trailer coupling control unit has been replaced, the coding must be customised to the vehicle equipment so that the control unit knows which trailer coupling is installed and which functions are desired or necessary.
- Automated folding/pivoting is synonymous with comfort closing in power windows. Touching the button is sufficient to fold/pivot the trailer hitch. => 669619 Removing and installing control unit for trailer hitch - "Information" section.
- The No automatic folding/pivoting option can be coded if there are doubts about safety. The button then must be kept pressed until the trailer hitch is completely retracted or extended. => 669619 Removing and installing control unit for trailer hitch - "Information" section.
- With or without operating button; the operating button must be activated for the pivoting trailer hitch. This is of course not necessary for the detachable towbar.
Versions or equipment features can be read out and reactivated under the Coding menu item.
The following options are possible:
Operating pushbutton:
- With operating pushbutton
- Without operating pushbutton
Version:
- Trailer coupling with detachable ball hitch
- Trailer coupling with automatic folding out/swivelling of the ball hitch "Comfort folding"
Country:
- RoW
- USA (North America)
By actuating the F8 button the code is memorised. Where necessary erase fault memory.
Information
- If the coding does not match the vehicle equipment, faults may be displayed that are not really present.
- The control unit does not function without a valid coding entry.
Information
Permissible combinations
Information
- Ensure that only permitted combinations and existing versions are coded.
Subsequent work
Install the side trim panel at rear right. => 700319 Removing and installing side trim panel for rear luggage compartment - "Installing" section.
Working Time
66961900: Removing and installing trailer control unit; Labor time 180 TU