Negative switch problem, slightly different from normal.

Does the the actual switch not have a built in relay ?

Alix786 wrote:

Does the the actual switch not have a built in relay ?

No it won't.
At this point I think you need to seriously consider getting an an auto-electrician involved.

I think I will have to 😁

Iv done plenty of simple electrics on my current vehicle ( Zafira VXR) so didn’t think this would be too difficult. However for a rear fog lamp I seem to be getting different opinions on how to fit it.

I may just let an auto electrician deal with it.

Depending on your confidence level, you could try a pre-made kit. Something like  THIS

The difficulty I have with premade kits like that is the lack of specific details, that one claims to be for fog lights & LED bars (in the description at the top), and fog lights & off-road lights (in the description at the bottom) - the problem here is that those lights are wired differently - you want fog with low beam, and off-road or driving lights with high beam.  Based on the instructions for that particular kit, you can have the fog/off-road lights on with no other lights on, putting the end user in a situation where he/she is non-compliant with legislation.

There is also no mention of whether that harness works with positive or negative switched lights which is also a critical factor.

There is one more thing I'm curious about and it may be specific to rear fog in the UK, the diagrams I've looked at don't use a simple of/off toggle switch, they seem to use a push-on, push off switch that feeds into an electrical latch circuit - you push one button to turn on, a second button to turn off, but, if the fogs are switched off for any reason, say the headlights are turned off, the rear fog goes off and stays off until the on button is pushed again.

The circuit seems to be designed to minimize the possibility of the rear fog being on unless the driver deliberately switches it on.