My pickup is about to drive me nuts!! I cant get my rear clearance lights to work. They were fine until a couple days ago and then boom, nothing. I got a warning from the cop and I dont feel like getting another one. The lights in front work so I know the problem is in the rear end. Is there a specific way to take wires off the frame and test them or a way to check for a short or broken wires. If there is please let me know.

Fordman

 

First never punch a hole into the wire with the
ice pick style electrical test. When you do this it crushes the soft poor quality copper that was used for wiring. Metallurgy was not quite what it is like todays alloys. A bruised wire can cause weak lamp lighting on an already low voltage system AND from EXPERIANCE can cause the wire to overheat and catch fire. The fire will definately force you to rewire. (If you have to expose the wire to test it; Remove the fabric sock, black electrical tape and use a cigarete lighter to slowly heat away the plastic wire skin. Dont hold the lighter on the wire until it glowing red
because youll just weaken its composition)

If you can chase the wiring to the rear; there should be a point where youll fine quick connects.
The quick connects have a male and female on each wire run.
These quick connects are usually located near a change over for the body or a service feed for more than one electrical component.
Ex: At the rear of my truck I have two wire runs.
One for the Right rear lamp and the Left rear Lamp. They were located under my truck bed near the rear driver wheel with the two qick connnects.
I checked the power at the quick connects and found that both runs worked. I then checked my lamp pig tails and found that they had corroded.
I was still having problems with my Plate light fisheye bulbs not working. I had to run a ground wire from the fish eyes on the bumper to a bolt on my truck bed to make a ground so that they would work.
Always check your grounding first to save yourself alot of time and fustration. Simply clean the areas where the metal light housing comes into contact with body.
Remember that these vehicles were made at a factory so most wiring is some type of harness for assmebly line speed. The harness for my right rear lamp has a quick connect that plugs into the harness coming from the cab. The same goes for the left rear lamp.
Oh the fisheyes are piggy backed off of the rear lamp in parralel to my running light wire.
Good hunting.

 

You may have already done so, but I would advise checking ground first. I've had more than one Ford pickup on which the front lamps worked fine, but the rears lost their ground. Just run a jumper wire from a good ground source to the lamp housings and see if it makes a difference. Good luck!