Towing electrics funny business

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Ben82
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Towing electrics funny business

Post by Ben82 » 08 Aug 2015, 10:28

So went to tow a trailer today. And couldn't due to the electrics not working properly at all, stuff would light up on the trailer, but indicating left would make the gearbox tick (as in locking and releasing the gear lever). And it would just fade the lights at the back

Annoying so have had to use cay's step mum's i20 to tow wasting an hour.

Any ideas? I don't have a trailer thing to test with to see if it rectifies it

Thanks

Xantidote
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Re: Towing electrics funny business

Post by Xantidote » 08 Aug 2015, 15:49

My first check would be that the earth circuit's OK. Have a look at the pins/sockets at the tow ball connector - you may find a bit of corrosion which you could clean up with fine emery or Wet & Dry.

Cleaning up a pin isn't so bad, but a socket's not quite so easy. My only experience of this has been on a 7 pin plug & socket. No doubt more difficult if you have the more modern 13 pin, as everything's a bit smaller.

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Re: Towing electrics funny business

Post by Ben82 » 08 Aug 2015, 22:36

Thanks Xantidote,

Mine has a 7 pin one, and the guy tried spraying some 5-56 (basically WD40) in the socket etc to no avail. I think I'll have to dig up SEDRE and check the wiring diagrams, and possibly try testing for a short. May even whip out the lexia to see if it shows any faults or shorts to ground.
I have two problems though, trying to get it fixed this week before towing next weekend again, and being able to test to see if I've managed to fix it. I might take a look under the car around the socket to see if I can see anything exposed.

It could also be the case that the previous trailer we towed was a 7 Pin one, rather than using a 7pin to 13pin cable that these trailers used.

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Re: Towing electrics funny business

Post by RichardW » 08 Aug 2015, 23:05

Sounds like classic earth fault territory to me. If it works OK with nothing connected, then it's in / around the socket / wiring. Unlikely that SEDRE will cast any light, as most likely the bar and socket is an after market one, with shoddy wiring! Lift the boot carpet and see where the 7 core cable goes. The white wire is the earth one - socket diag here this will be as you look at it. You should be able to measure continuity from pin 3 to earth on the car. If the inboard end looks OK, then chances are water has got in the socket - probably rendering it scrap. You will need to cut it off and fit a new one - don't know how easy finding a 7 pin socket will be in Sweden though!??

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Re: Towing electrics funny business

Post by Ben82 » 08 Aug 2015, 23:26

Thanks Richard, our semi-equivalent to halfords seem to have a universal one :)

Yeah the towbar is an after market one - a "Kovil" one to be precise. The towbar is detachable too so hopefully makes it a bit easier to replace the socket if need be. It might be worth replacing the socket anyway (it's only £7!), as the foglights have never worked since I've had the car (even though I've tried a new bulb), and I remember a thread on here saying that the cause of that is generally the towbar socket.

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Re: Towing electrics funny business

Post by Xantidote » 08 Aug 2015, 23:52

The wires into the back of the 7 pin socket are fixed to their brass conectors with steel screws, and these can get really rusty/cruddy over time. Could be where your problem lies.

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Re: Towing electrics funny business

Post by Ben82 » 08 Aug 2015, 23:58

Is there such a tool for testing the towbar socket,? Eg something with a bunch of w5w bulbs in that simulates the whole setup to ensure it's working? Seems like it's something really simple to have available.

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Re: Towing electrics funny business

Post by Stickyfinger » 09 Aug 2015, 00:49

Yep....a multimeter
Image

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Ben82
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Re: Towing electrics funny business

Post by Ben82 » 09 Aug 2015, 08:17

I really meant something that would recreate the issue so can verify it's fixed without hiring a trailer to find out if it is or not :)
Do have a multimeter though, but it's packed somewhere :(

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Re: Towing electrics funny business

Post by Xantidote » 09 Aug 2015, 09:48

Thinking "outside the box", is it possible that the fault was actually in the trailer's wiring, and we're going in the wrong direction?

There must be some electric gismo, as my MoT man told me my 7 pin socket was throwing up a fault. Told him I was using the "spare" pin as a power lead, and he accepted that. I disconnected the lead for the next MoT. None of this much help to you, as you're in Sweden.

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Re: Towing electrics funny business

Post by Ben82 » 09 Aug 2015, 09:51

We thought that at first, two sets of cables were tried along with two trailers :(
And then once we got the i20 there it worked fine, so most likely the car's electronics unfortunately.

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Re: Towing electrics funny business

Post by Stickyfinger » 09 Aug 2015, 11:23

Ben, really just check for good connections (bet they have used the Evil that is "The Scotchblox"), then check the earth, then use your multimeter to check the live earth pins....10mins
The ticking in the glove box is a relay for the indicators, thus the advice re earths is likely to be correct, either that or its not loading the flasher relay correctly with the extra bulbs on it if direct wired.

A Mk1 should have no problem with a simple trailer wiring setup. Does yours have a box/multi relay or is it directly connected to the wires ?

From my notes this is what I had in my old one....

Left rear light:
- brake - green - 2101
- tail light - blue - 263
- indicator - yellow - 289
- fog - purple - 201B (in a RHD)
- reverse - white - 290 and 242 (in a RHD)

Right rear light:
- tail light - orange - 264 and 256
- indicator - orange - 290
- brake - brown - 2100 and 246 (not used for towbar but noted here)
- fog - white - 201A (not used but mine is RHD)
- reverse - red - 224 (not used but mine is RHD).

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Ben82
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Re: Towing electrics funny business

Post by Ben82 » 09 Aug 2015, 16:45

Does the towbar electrics go into this box?Image thought that would be for the reversing sensors :/

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Re: Towing electrics funny business

Post by RichardW » 09 Aug 2015, 20:36

Suspect you are right with the reversing sensors on that box.

Easiest test is get a trailer board - only about £13 on e-bay - that way, once you've got your plate on it, you can fit it to any trailer, and know the lights will work, and you've got the right no plate on it!

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Ben82
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Re: Towing electrics funny business

Post by Ben82 » 09 Aug 2015, 20:52

RichardW wrote:Suspect you are right with the reversing sensors on that box.

Easiest test is get a trailer board - only about £13 on e-bay - that way, once you've got your plate on it, you can fit it to any trailer, and know the lights will work, and you've got the right no plate on it!
Unfortunately every single trailer over here is registered themselves so they each have their own number plate on. They even get a MOT each year too.

I think I may have found the problem as I was doing some multimeter tests with Cay's Mum's car.

On mine the Indicators have a nominal off voltage of 0.02, their's was ~3.8. The rest seemed to test fine... battery voltage on the side lights, and changing for the indicators up to about battery voltage for on (the multimeter wasn't refreshing fast enough to give an accurate indication).

But basically the earth is good, and that's the only difference I could find... maybe missing a 5V reference or something if they're supposed to give some voltage even when not indicating?

Am I on the right track here or is that a difference between tow bar sockets? (both were 7 pin)