Does anyone have a wire diagram for the rear harness that is at the rear of the frame and plugs into the body harness that powers the rear turnsignals and reverse lights and markers? Its a 8 pin plug. My rear lights are not working and I need to meter the plugs. I think I have a wireing problem. Its the one next to the trailer harness plug. Thanks

 

Here's what I have (1999):











Chris

 

Thanks . I used your diagram and I am only getting 2.5v on the brown taillight wire. Now I need to find the next splice/plug in line. Mabe by headlights? This did all happen right after I replaced my headlight bulbs.

 

When you saw 2.5V on the brown wire did you have the negative lead of your meter on the chassis or on the black wire going to the tail light?

If you were measuring from a known good chassis ground then your trouble is in the feed (brown wire), but if you were measuring from the black wire your trouble could be on either side of the circuit.

Chris

 

I was testing from a good ground to the brown wire. I believe I now need to find the brown wire at the plug under the brake master cylinder under the hood(next possable failure point?). Wish I knew which one. I can see three but I can't see down there verry well. The next splice/junction after that is labeled S107 I believe. My guess is it's the plug below the master cylinder. All other parking lights work fine.

 

Sounds good. I'm not sure which of those 3 connectors it is but you're on the right track .

Chris

 

It's raining here which is a miracle because we are in a severe drought. So my troubleshooting has been postponed. I need to fix this as this is my daily driver but we need the rain more than I need my lights.

 

The storm that rolled through here this morning must have finally made it to you. Not sure how much we got but it was a nice steady rain for about 4 hours. Just judging from the puddles I would say close to an inch, which is the first time we have got more than a 1/10 since June. Its sunny and heating up again now, so soon you can go back to working on it in the nice humidity

 

I found the plug under the hood, and the wire from under the hood to the rear behind the bumper is the problem. Does anyone know if there is a plug behind the fuel tank for a dual rear wheel fender parking light harness. My truck is a SRW but I was wondering if the harness is the same then there may be a splice and a plug between the fuel tank and the frame. It's verry hard to see in there. Thanks

 

I just fixed mine do to almost identical problem (rear running lights & license plate lights wouldnt work). Turned out that the brown wire snapped right after it comes thru the frame & before it plugs into the harness. Id say if you cant seem to find the section thats bad just find it somewhere in front of the gas tank (if thats where the problem area is) & run a new positive wire back.

 

Yes I thought about the running of a new wire but I am a low voltage electrician and like to keep things as original clean and factory as possable. But I will run a new wire if necessary. Hopefully I can find the bad spot and repair it. If I run a new wire il have two connections instead of one IF I can find the bad spot. All of the wire I can access looks good, no hard spots. I just can't get behind the tank.

 

Hello, does anyone have a wire color guide for the Tail light harness coming out of the frame harness at the 7 pin plug? (92 F350)