Trailer electrics

S

Silverbrewer

Member
I have just fitted a towbar and I am now starting on the electrics!!!!! I have bought a 7 way bypass relay, and I have found the Audi's wire colours for the various circuits I need to tap into.....my question is....Is there a socket somewhere within the hindquarters of the car that provides these wires all in the same place, and if so, where is it?

The Audi current flow diagrams show a connector designated U10 I think that is the connector I am looking for, but it may be that U10 is the actual trailer socket that the trailer plugs into that is fitted to the tow bar! Does anyone know? I could then just connect all the bypass relay wires to that connector and then connect the bypass relay terminals to the trailer socket....well that's the plan anyway....

Recent info...U10 is indeed the trailer socket that the trailer plugs into and not a socket inside the car. I have looked behind the nearside loadspace panel and found looms containing wires I could use, I have not removed the offside trim yet, but surely Audi technicians are not expected to break into the loom and connect to the relevant wires! Audi must do a loom that goes between U10 and the car!!!!!!! Audi's circuits show wire colours dedicated to the relevant circuits arriving at the back of the trailer socket U10 and going off to various points in the cars circuitry, so we are not talking about a bit of 7 way trailer cable from Towshure!
 
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especially if you have DIS, you *will* need to run at least one cable to the front of the car.

The rest of the loom I'm not sure about but remember that 58R and L are seperate, so it's quite possible you'd have to break the original loom!

Bret
 
I am going to get power for my relays from the cigarette lighter in the centre consol. That is fused at 15 amps and is a permanent power feed which is what the relays require to power up the trailer lights. I will earth the relays at one of the tail light mounting screws.

I am then going to cut into each circuit wire behind the left 1/4 panel in the load space for all the other wires to the relays. I will snip each wire and then re crimp it with a high quality insulated in line crimp which will include the additional branch off to the relay at one end of the crimp. I will include a length of pre-glued heat shrink tube on each crimp and once tested will shrink it into place providing a waterproof, strain relieving seal to the new connection. (no "skotch lock" crap here!)

The relay board itself, which is about the size of a fag packet, will be mounted behind the left hand 1/4 panel and the 7 way wire to the trailer socket will exit the boot floor through the grommet that is already provided under the emergency triangle holder. (You can see it if you look up underneath the car.)

Can anyone see any problems with that?
 
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Well I thought of doing that, or going into the drivers fuse box on fuse 10 as that is where power should come from, but with the cigarette lighter socket quite close and un-used, it just seems easier and just as safe.
 
And when I say I am using the cigarette lighter, I don't mean I am pluging into it!! I am linking into the wiring on the back!!!
 
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