Mercedes towing electrics

[Deleted member 11979]

I have a problem with the factory fit electrics on our 2011 GL.

With the ignition off and for maybe 5 seconds after turning it on, all the trailer lights work correctly. The lights are filament.

Once the ignition is on only the trailer brake lights work, the others giving the blown bulb message on the dash as you try to use them (once you indicate for exampleit throws up the blown bulb message for that bulb and the bulb doesn’t light)

All the fuses seem ok, it’s been on a Star machine and no faults found.

Before I randomly shell out for a new SAM does anyone have any ideas?

Many thanks

 

[pmcgsmurf]

It sounds like the trailer lights are drawing too much current and being switched off by the system.

You could maybe try swapping for example one of the turn lamps for an led to see if that helps.

 

[Deleted member 11979]

It sounds like the trailer lights are drawing too much current and being switched off by the system.

You could maybe try swapping for example one of the turn lamps for an led to see if that helps.

that’s a good idea, I’ll give it a go, thank you

 

[Benzowner]

It could well be cheap filament bulbs. When I had my e class, a bulb blew, stop light, I replaced the bulb with a cheap replacement and although it was working fine still showed a blown bulb. Replaced it with a decent make and all was well.