Relay for towbar electrics - W210

[ArcherL]

Does anybody know should I use a bypass relay when fitting the electrics for my towbar on my W210? Some companies say yes and some no.

 

[Dieselman]

Yes.
It can possibly work without but could be overloading the electric supply and cause bulb warning issues.
You need a warning relay anyway so just fit a full 7 way bypass and warning light in the dash cluster is a nice touch as well.

 

[ArcherL]

What is the warning relay for? I've fitted towbars before and have not used one. Where does the warning light go in the dash, I'd like to go that way if it's a nice touch. I'm getting the towbar today so I'll get the relay at the same time, thanks for that.

 

[Dieselman]

You have to have either visual or audible warning of when the trailer indicators are flashing, but not activated unless the trailer is hooked up, hence the warning relay.
For a visual warning on the dash fit a clear LED into one of the blank warning light apertures then power this from the fuses nearby and run an earth back to the towing relay.

 

[ArcherL]

I don't think that level of sophistication has reached us in the green Isle here yet or is it an EU rule? I'll do it anyway, sounds good, thanks.