Rear Fog light. Help please!
 

Hi Guys

I don't know if you guys in the USA have a compulsory rear fog light fitted but I hope you give me a pointer or two here.
My wife's MOT (annual roadworthyness inspection in the UK) is due next week, (well the car's MOT is due, my wife seems Ok for her age! ) and she mentioned to me that it's booked in for Tuesday. So I go out to check over the car. Found the rear fog light didn't work- bulb failure light came on when I pulled the switch.
Cut a long ( 4 hours) story short, it's not the bulb. Not the fuse - No. 4. I have no power getting to the rear light fog light bulb. The rest of the lights are 100% OK.
Pulled the dash around the light switch, switch seems 100% OK.
Tried to trace what was going on, moved a cluster of wires under the dash just above or adjacent to the drivers feet. And it worked! ( I had the engine running and the lights on and saw the bulb fail light go out. ) Check at the rear and yes it was on. Tapped and fiddled and shook wires, all seemed fine. I obviously wasn't too happy as I didn't know what I did to get it working but hey, it worked. Tidied up the wiring and the bulb failure light came on, and yes, the fog lamp was out. More fiddling, tie-wrapping the loom next to the drivers feet, and it came back again. Any ideas?
Anyone had this? There are many connectors above and next to the pedal area but all seem fine. I tried tracing the wire through, (it's a grey/green) but can't see it once it comes out of the light switch. I've taken the fuse box apart and all seems well there, and I swapped the fuse for a new one just in case.
Help!

Barry
1994 E200 Wagon 116k miles

Barry,

My 1986 190E 2.3-16 central locking system suddenly stopped working, and I ended up tracing the power line to a location under the driver's side (US car) footwell. Over the years there was apparently enough of snow on my feet and other sources of water/dirt to fill a channel where the wire went under the flooring so that a crack in the insulation on the wire led to corrosion of the copper. The copper was literally pure copper oxide at one point and jerking around on the wire would intermittently allow the solid copper ends to contact. I cut out the bad section and replaced it, then wrapped the whole section in electrical tape. It has worked for 6 years since.

The point of this discussion is you have an intermittent connection and until you trace the wire you will be depending on some kind of luck to discover the problem. In all likelihood the area of the problem is within a few feet of the wiring harnesses you were pulling on, so I would trace the wire from the tail lamp back to that area. Hope this helps, Jim

Jim

Much obliged. I guess there's nothing for it but to get upside down under the dash.
I knew I would have to, but wondered if anyone knew of any connectors that were prone to this type of fault.

Cheers

Barry