E class estate 211 towbar electrics

[gullen]

I have a current rhd 211 estate 320cdi. An approved towbar fitting company has installed twin 12n and 12s electrics that omit reverse, and also cause the parktronic to come on briefly and then be disabled. This is due to multiplex wiring I assume. They seem unable to resolve the problem. Has anyone had similar problems or know of an aftermarket wiring kit that will work incl reverse and not affecting the parktronic. A 13 pin solution is acceptable.

 

[teky]

seems to me they would have to disable the parktronic when the trailer is on, sort of a switch off loop in the connection when the plg is in

 

[teky]

or add sensors to the caravan as a link in system, more complicated that way because it still would have to shut the car system down

 

[gullen]

i still want the parktronic to operate although obviously when in reverse it will recognise the caravan - that is not a problem. I believe the factory fit towbar electrics are ok , so don't understand why the aftermarket kit that has been fitted doesn't work properly

 

[Arnie]

Probably because it's an aftermarket kit rather than original equipment.

I would imagine that if it is tapping in to he CAN-bus-controlled multiplex wiring, that the adapter will need to be recognised and programmed into the car's control electronics. This is probably where it's going wrong. I would return it for a refund and get a Mercedes one.

The alternative would be to take a pair of power and ground leads, rated at 30 A from a suitable auxiliary fuse, connect them to a bank of 12v automotive relays (halfords) in a small plastic electronics box (maplins), with one relay assigned to each of the light functions (brake, side, reversing, indicator L/R etc. box and then use signals tapped from the rear light-clusters to operate each relay, feeding the coupling socket. This should leave youre car's parktronic and other functions undisturbed.


Actually, re-reading your question, maybe I have misunderstood what you are saying.

Do the new electrics plug into the existing socket, as an adapter, or are they a substitute for the orginal socket?

If the latter, it may be as Tecky said, that they have messed up an existing signal to determine whether a caravan/trailer plug is connected, thereby disabling the Parktronic. Check whether this is a standard feature of the factory-fitted kit.

Does your parktronic work as normal with nothing plugged in? If not, then it support the above.

 

[gullen]

Parktronic works fine with nothing plugged in. The electrics are not a substitute nor even a plug in but I believe just hooked up with scotchlocks in the normal way with various relays etc. The mercedes item , both for original and retro fit i blieve is a plug directly into a socket on the rear fuse box. Several manufacturers now provide these sockets to avoid retro fitters messing with the wiring. Problem is the mercedes wiring kit only comes with towbar and not on its own, so expensive option to go for that but am still waiting on fitters to say if they will go that route or still try to find a technical solution!