A friend told me that my back up lights were not working. First I went in and cleaned the contacts and replaced the bulbs. But what I have now is strange. With the truck in reverse neither light comes on but the brake lights are on, but dim. If I take the left hand B/U bulb out the right one comes on and if I turn on the head lights the brakes lights go out. By brake light I mean one of the two filaments in the upper bulb it is the same element that blinks with the turn signal. And speaking of turn signals they stopped working since I started look at this, but the hazards still work.

To add to all this now the truck won’t start with the key, a problem I thought I had cured with a new ignition switch the other week, I can still start it by putting the key in run and using a bump switch on the solenoid.

Any ideas?

 

Both of those problems could be related.

Does the truck have a Automatic transmission?

It seems you have a wiring problem with either your frame rail harness or Rear wiring harness. I would bet on the frame rail harness right now. I would remove them both from the truck, unwrap the black plastic covering from the wires, inspect and repair wiring, then rewrap with electrical tape.

All those problems you described could be due to the frame rail harness being damaged.

The Neutral Start Saftey switch, which also controls the backup lamps, and keeps the truck from starting in gear ; the turn signals, and brake lights are all wired in that same harness.

Hope this helps.

 

If it worked before you touched it and it doesn't now...it is something you did!!! You probably changed to a bad bulb. If the filiments touch and a dual filiment bulb you get all kinds of wackyness going on (bleed through). I would change the bulbs to fresh ones (1157's on the stop/tail and front turns/runners and your 1156's on the backups) before I tracked down wiring. The other simple check is the ground to your bed...a bad ground will cause some of the same issues.

Kenny

 

Sounds like a bad ground to me.

 

I would tend to agree.

But since he is having problems with the truck not starting as well, in the way he describes, he needs to check out the frame rail harness for damage, and eliminate that as a possible problem. First. IMO.


All the components that he is having problems with are all "connected" together in one component on the truck. The Frame Rail Harness. The components themselves are not connected together with wires, but the wires take the same path to get to the front of the truck in the frame rail harness if you understand. If it is damaged, IE: he hit some debris or something, wires can break and/or short together in this harness causing ALL the symptoms he described, all in one place.

1: Make sure the Frame Rail Harness is not damaged which contain wires for:

Neutral Start Safety Switch - Which also controls backup lamps, and not alowing the truck to start in gear.

The Turn Signal lamps, brake lamps, parking lamps, tail lights, etc...

2: Make sure the rear harness isn't damaged. etc...

Make sure you have a good foundation first, "the wiring". Then work up from there.

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If he has good wiring, and still has problems, then he would need to check:

1: The Neutral start safety switch, make sure it's adjusted properly, and/or replace if defective.

2: The Lamp Sockets. Make sure the lamp sockets are not damaged. Bad lamp sockets can cause simular problems.

3: Check and replace the Turn Signal switch if nessecery if the lamp sockets are good.

My two cents...

 

I decided to replace the neutral start/back up switch just on GP. After I pulled the rear light harness and removed the spliced in trailer harness and just generaly cleaned it up and re wrapped it, I discovered that the ground plug had no continuity. Two cuts and 2 crimped in spade terminals and the problem seems to be solved.

I noticed that bulb socket are a little touchy about how the bulbs go in, the spring contact are probably weak and corroded, I bent them up a little bit and all is working, but I bet new sockets would be a good idea.