Fault Code 2579

Fault code 2579

Left brake light, trailer

NOTE:
- This fault code can only occur for NAR (North America) coding.
- This fault, together with all other lighting faults, is saved only by the last trailer. This means that if another trailer is detected (trailer in socket), all lighting faults are first erased.

Diagnostic conditions
- Ignition on
- Trailer hitch control module, internal function test
- Trailer detected through plug in trailer socket

Possible causes of fault
- Left brake light/direction indicator light bulb faulty, trailer
- Open circuit in left brake light/direction indicator light electrical circuit; vehicle and/or trailer
- Short circuit to ground or B+ in wiring; vehicle and/or trailer
- Trailer hitch control module

Affected pins
Trailer hitch control module, plug A:
- Pin 7

Trailer hitch socket:
- Pin 1

Diagnosis/troubleshooting

NOTE:
- When troubleshooting, the status of the fault must be observed.
- Use a suitable test cable or a trailer (which is definitely OK) to check whether the fault is present on the vehicle or whether it is reoccurring.
- A short circuit to B+ can also be a short circuit to supply leads of other loads. The leads must be supplied with power for test purposes.