Rear foglight help needed

[RLambert]

Hi,

I'm trying to get the rear fog lights connected up on my US spec 964. I need to get this completed tomorrow as it's going for an MOT on Friday...

There isn't a rear fog light switch but the fog lights with bulbs are in the rear reflector and the wiring is connected up. I found a spare switch connector behind the dash where the rear fog switch normally lurks and the wiring colours seem to match up with those at the back of the car.

Firstly there wasn't any power to the connector but I worked out that if you switch on the front fog lights then there is power to the rear ones although the rear ones still won't come on ! Also when you switch to high beam then the fogs switch off.

Can someone please confirm if you need to have the front fogs on for the rears to work ? Do you also need the headlights and ignition on ?

I'm at a loss to work out what is going on. Can anyone help ??

Thanks
Richard

 

[johnk]

i am not sure if its the same but i had a 993 fail mot today on rear fogs,

you have to have lights on and front fogs on and rear fogs will then come on when all pulled, what i found was the pull switch for the rear fog was unscrewed causing it not to work, so screwed the switch knob back on and hey presto it worked...

just out of interest when you turn the headlights on do all the switch faces light up

 

[RLambert]

Just been out to check.

When I switch on the lights both switches light up. When I put on the ignition and pull out the switches they both light up more brightly.
I checked they were screwed in fully and they are.

Any clues ?

 

[Dave Wilkinson]

Richard,

You are correct in thinking the rear fogs only work when the front fogs are on. I believe that's the way Porsche set it up because that's the legal requirement in Germany. In some markets (I think, Canada) the front fogs are used as day time running lights and there is a relay which is fitted to enable that function. In other markets that relay is omitted.

When the light in the switch comes on bright it indicates that the relevant ligfht should be on. Because the US cars don't have the rear fogs fitted there is a chance that the previous owner may have fitted the euro-spec rear reflector unit but there may be something in the wiring missing or not connected. AFAIK the 964s have most of the wiring for all options fitted as standard although there is a chance that different markets may differ in some respects.

Good luck with the fault finding.

Regards

Dave