Hi.

The installed 7-pin trailer connector on my Fabia I combi (6Y5) is very flaky, and my plan is to replace it with a new 13-pin connector, which most trailers have now and not need to to use the bulky 7- to 13-pin adapter

However when the old connector was removed i noticed there was an extra cable going to a little switch which is grounded (pin 3) when a trailer is not connected (i guess).

What is this extra cable used for? Is it possible to just rewire the normal 7-pin to a 13-pin connector?

I do not need constant power or ignition switched power to the trailer.

I came across this before in my son in laws vw caddy. Never seen one before. It disables the cars rear fog light and also the rear parking sensors plus a few other things to do with stability control. You can get a 13 pin socket with microswitch.

Alasdair

Ahh, thanks for the information Alasdair.

It makes sense to disable these functions with a trailer connected.

Actually I found a diagram from a trailer manufacturer, and it seems as the standard specifies that pin 12 and 13 is interconnected in the trailer, to indicate that a trailer is connected to the car. This might actually be used in conjunction with a switching relay (NO to NC) to disable these functions.

I will do some tests and report back.

Thanks again.

Confused me. Saying that all my cars were old school seven pin and no reverse sensors etc. Not a bad thing though. Nothing worse than the glare of a fog light bouncing of a caravan back at you.

Alasdair

Connector replaced and tests done.

Wiring for tail-, turn-, brake lights and ground was straight forward.

The switch in the connector and the extra wire was used to disable the rear fog lights on the car when a trailer is connected. I could not identify that the wire was used for anything else and the car have no rear parking sensor.

Somewhat confusing and took some time to figure out, was that the original wiring in the car do only include wiring to the left rear fog light. But the trailer connector wiring which plugs in between the original wiring at each rear light did connect both rear fog lights.

Thanks again Alasdair