Rear Fog Light Troubleshooting

[Technik21 0]

205 Gti 1.9 (1993)

 

Car electrics isn't my strong point, and I need to figure out why my rear fog light isn't working.

 

Yes, I can take the car in to a garage\auto electrician, but in the meantime (weekend) I was hoping I could try to troubleshoot the problem.

 

There is no power reaching the rear fog light connector. I have checked the fuse (ok), and tried swapping the panel switches around to test the switch. Still no power.

 

The only solution it seems to me, is to trace the red & green\yellow cables from the fog light unit back towards the switch, but that in itself is difficult, because the cables run up and behind the bumper, and in to the (I presume) Nr side rear quarter panel.

I have peeled back the carpet to the near side quarter panel, to reveal a whole bunch of wires and terminals, and then I guess the cables run under the rear seats towards the dash.

 

I was wondering whether to make a small nick in the red wires that run under the rear seats (3 x red wires amongst the other colours), and put a meter on each one to check at least that current is getting that far.

 

So if anyone has a more sensible \ alternative approach, I would be grateful.

 

I need to get the car MOT, so a rear fog light that isn't working is a sure failure to begin with.

 

Thanks Guys

[Henry Yorke 269 3 Cars]

Is power getting to the switch in the dash? Does the switch illuminate when pressed? Have you checked the connectors on the back of the foglight for corrosion (very common)? Is the bulb ok? Are all the connectors on the fusebox connected right? Is the earth wire connected tothe earthing block behind the passenger side rear light.

 

the way to test whether a wire is broken is to find both ends of it an perform a continuity test. Put a multimeter on each end of it and measure the resistance (ohms settings on the multimeter) . If there is a decent reading then the wire is fine. If the readings are zero then it means the wire is broken.

 

I'm no electrician either but this would be my intial check list so I hope this helps. I find wires very rarely are broken and it is often a connection issue.