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towing electrics help
number-1 - 31/5/19 at 07:58 PM

I use a Renault Sport Megane 225 as my daily and also to tow a motorcycle to track days.

When the trailer isn't connected, all the lights work fine. However, when the trailer is attached and plugged in all is good too......until i turn the lights on. When i turn the lights on, the lights on the car and trailer come on but the brake lights on the car come on and stay on. The trailer brake lights do not unless i brake

Any ideas? Its got the Renault plug and play tow bar electric wiring fitted.

rusty nuts - 31/5/19 at 08:08 PM

First thing I would check would be the 7 or 13 pin plug and socket for poor connections

number-1 - 31/5/19 at 08:15 PM

I've ruled out the trailer by buying a new trailer board and it still does it

ReMan - 31/5/19 at 10:04 PM

Check the insides of the socket, car side. These are renowned for corrosion

number-1 - 1/6/19 at 10:14 AM

Cheers guys. I had a quick look car side for anything loose but nothing obvious. Its weird it doesn't do it unless the lights are on. I will have another look tomorrow.

ReMan - 1/6/19 at 10:51 AM

Its an odd fault. Might it have always done this but you not noticed?
Are the lights on the car coming on definitely the brake lights not fog lights?

Bigheppy - 1/6/19 at 11:21 AM

I had a problem with my fog lights on my car. After plugging my trailer in I noticed that the fog lights were not working on the car but worked fine on the trailer. When I unplugged the trailer and the fog lights still did not work.
After some advice I found that the trailer socket has a switch to turn off the fog lights when the trailer is connected (I had never noticed this in the two years I owned the car). After checking I found the switch had stuck. A bit of fiddling around soon had it free and working fine.
I realise its a different problem to yours but might be worth checking.

rusty nuts - 1/6/19 at 12:30 PM

For what a 7 pin socket costs you might as well get a new one rather than trying to clean up your old one , I tend to smother the insides with connector protector

ReMan - 1/6/19 at 03:32 PM

quote:
Originally posted by Bigheppy
I had a problem with my fog lights on my car. After plugging my trailer in I noticed that the fog lights were not working on the car but worked fine on the trailer. When I unplugged the trailer and the fog lights still did not work.
After some advice I found that the trailer socket has a switch to turn off the fog lights when the trailer is connected (I had never noticed this in the two years I owned the car). After checking I found the switch had stuck. A bit of fiddling around soon had it free and working fine.
I realise its a different problem to yours but might be worth checking.


Good call, again this could cause problems bependant on the fault and the tow car

chillis - 2/6/19 at 10:33 AM

I've been having a similar problem with the Mondeo which has the Ford towing electric harness and modules. When the towing electrics are in circuit and the brakes are applied with the left hand indicator then the relay buzzer goes mad and the LH rear flasher doesn't flash, take the towing electrics out of circuit and its all fine.
Pin out between the towing electrics and the modules shows connectivity and no shorts to ground. Seems most likely its the modules. If you Renault has a similar system then I would be inclined to the the modules too might be the issue.

number-1 - 3/6/19 at 08:49 PM

Cheers guys

I removed the bumper to find the loom had dropped and was resting on the tail pipe and melted a few wires so bare wires were present and grounding. I taped them up and the issue is corrected