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Towbar wiring advice

Discussion in 'A4/S4 forum(B5 Chassis)' started by volvo1980, May 28, 2011.

  1. volvo1980
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    volvo1980 Member

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    Well I have finally got a detachable towbar off eBay for my 2001 avant but I am just after a but of wiring advice, does anybody have a wiring diagram for single electrics and do I need a bypass relay? The guy I have bought the towbar off stated that he didn't need a relay but that was a pre facelift car.
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  2. mattpanton
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    mattpanton Member

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    I fitted a towbar to my 2001 avant last year, I used a full bypass jobbie as I was a little concerned about the towbar wiring setting off bulb failure warnings on the tail/brake light circuits. As for a wiring diagram all I did was tapped into the wiring coming off the back of the lights clusters, using the location of the bulb as reference. I can have a look tomorrow at what is wired where if it would help?
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  3. volvo1980
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    volvo1980 Member

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    I have found some info and because they have canbus from 2000 so apparently I need a bypass relay, should be ok with the wiring, where did you take your constant live from for the relay? Thinking of taking it from the power socket in the boot.
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  4. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    "Canbus" has nothing to do with the lighting.

    All B5's have bulb monitoring, and it doesnt use canbus on any of them.
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  5. mattpanton
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    mattpanton Member

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    I took my constant live from the boot power socket, did wonder if the circuit was up to running trailer lights but i've not blown the fuse yet so seems fine
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  6. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    Boot power feed can deliver 10A, which is ~120w of lighting. Even with both brake lights, fog light, reversing light and side lights on thats only about 100w
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  7. mattpanton
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    mattpanton Member

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    I never bothered to calculate it out, I worked on the priciple that if the fuse remained with as many lights on the trailer as possible then it would be ok!
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  8. OldRedEyes
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    OldRedEyes Member

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    I used a relay, and took the power from the boot light.
    As for connecting to the correct wire for the trailer lights, i soldered and extension cable to the back of the lights so that i didn't have to cut into the loom. DON'T use those **** clips that cut through the outer sheath to make the connection, they are ****.
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  9. volvo1980
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    volvo1980 Member

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    Thanks for all the advice and I should be fine now, anything has got to be easier than fitting coilovers to a 10 year old car as I found out on Friday! Just ordered a 7 way bypass relay so should be ready to fit next weekend.
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  10. mattpanton
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    mattpanton Member

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    I second that. Solder and heat shrink tubing is your friend
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  11. foursprungdugtechnique
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    foursprungdugtechnique Member

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    I got a Westfalia detatchable towbar fitted on my 2000 B5 last year.
    Power was from the boot power socket, got 13 pin socket fitted as it is the new standard for caravans, split charge relay, and bypass relays fitted, all wires soldered and shrink wrapped, perfect job.
    As previously mentioned DONT use the Scotch locks for connecting the wires, they are ****, and you will get a bag of them with the wiring. They would be as well flogging you a cheap soldering iron, at least it wouldnt get wasted
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