No lights?
Moderator
Joined: Jan 2001
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From: Virginia
Unplug the harness at the rear on the driver's side just forward of the rear bumper. There should be a plug there where all the wires go to the rear lights. Then put a another fuse in place and see if it holds. If it does, then your problem is at the rear bumper area, and most of the time it's from wiring modifications for trailer wiring plugs.
That's what you are going to have to do. You will have to isolate different parts of the wiring to narrow down what end of the truck has the problem, since the brown wire goes all over the complete truck front to rear. The problem could be anywhere on any of the brown wires.
That's what you are going to have to do. You will have to isolate different parts of the wiring to narrow down what end of the truck has the problem, since the brown wire goes all over the complete truck front to rear. The problem could be anywhere on any of the brown wires.
Moderator
Joined: Nov 2007
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From: Denver Metro Area, CO
To add to that, the fuse is there to protect the wiring, don't keep putting in heavier-amperage fuses thinking you'll get it to work that way, what will happen is the truck's wiring will become the fuse (read: it will burn up).
FTE Legend
Joined: Jul 2010
Posts: 32,875
Likes: 48
From: Northeast, OK
Yep. One way to find the problem is just bypassing the fuse - whatever is shorted will burn up, and take a lot of other things with it. You were doing a good job of that with your bigger and bigger fuses. Either keep going and you'll soon find it, or stop and work through it logically.
Dave's suggestion is, as always, a good one. My only problem with it is that I've not been able to get any of the rear plugs to come apart without inflicting some damage. But perhaps yours will. If not, look around back there as that's the place that people who don't know what they are doing and shouldn't be allowed to drive a truck, much less work on them, usually do their best. If you find twisted together wires, wire nuts, scotchlocks, or anything less than soldering with heat shrink on it you know a rank amateur has been there. And given that the area ahead of the bumper is the absolute worst environment for electrical connections you have a recipe for failure.
Dave's suggestion is, as always, a good one. My only problem with it is that I've not been able to get any of the rear plugs to come apart without inflicting some damage. But perhaps yours will. If not, look around back there as that's the place that people who don't know what they are doing and shouldn't be allowed to drive a truck, much less work on them, usually do their best. If you find twisted together wires, wire nuts, scotchlocks, or anything less than soldering with heat shrink on it you know a rank amateur has been there. And given that the area ahead of the bumper is the absolute worst environment for electrical connections you have a recipe for failure.
pedant
Joined: Jan 2008
Posts: 23,576
Likes: 38
From: EXTREME southwest CT
Do you guys remember when I had that shorted harness connector in the engine bay?
I know my '87 harness is different, but I bought a self resetting circuit breaker so I could try and find the problem without constantly replacing the fuse while I was under the truck.
I know my '87 harness is different, but I bought a self resetting circuit breaker so I could try and find the problem without constantly replacing the fuse while I was under the truck.
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Joined: Jan 2001
Posts: 56,966
Likes: 2,728
From: Virginia
I can't take credit for that one(99% of the stuff I write I pick up from somewhere else) a guy who restores cars uses a battery charger when first testing a restored car instead of using a battery, just to make sure something is not wrong somewhere.
Moderator
Joined: Jan 2001
Posts: 56,966
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From: Virginia
You are correct, by now they are stuck and corroded pretty good. But I look at it as a "pay me now" or "pay me later" type thing. You might was well bust it apart, and put some other type of connector in there before it gives you trouble.
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Junior User
Joined: Jan 2006
Posts: 96
Likes: 0
From: West Haven, CT
So here's where I'm at.. I decided to replace the bulbs while i was in there and started to check continuity for the entire brown wire circuit. Everything says its good but I still have no lights in the rear. The fuse is holding at the recommend 15a, and the front lights work fine, now that I have unplugged the rear harness at the bumper. There is some shotty wiring back there, but the meter says everything has continuity. How do i determined what and where my short could be? or do we suspect the plug? There is normal voltage to the plug, but not to the lights. I'm not to sure how to check wires for proper resistances, etc.. Thanks everybody!!
pedant
Joined: Jan 2008
Posts: 23,576
Likes: 38
From: EXTREME southwest CT
Proper wire resistance is near zero.
Bulbs will have resistance based on their brightness.
If you have power at the plug and not at the lamp sockets, the break is somewhere in between.
Or the shoddy wiring is causing a short to ground.
Take the tail light bulbs out and check for continuity from the hot wire to ground.
Without the filaments in the circuit there should be none.
i.e. infinite resistance, not NO resistance.
Bulbs will have resistance based on their brightness.
If you have power at the plug and not at the lamp sockets, the break is somewhere in between.
Or the shoddy wiring is causing a short to ground.
Take the tail light bulbs out and check for continuity from the hot wire to ground.
Without the filaments in the circuit there should be none.
i.e. infinite resistance, not NO resistance.
FTE Legend
Joined: Jul 2010
Posts: 32,875
Likes: 48
From: Northeast, OK
I'm suspecting the poor wiring job. Or bad grounds. Depends on where you are getting your ground for your volt meter. If you are using a known good ground, like a shiny spot on the frame and still show no voltage at the bulbs then you have a wiring problem, and that is most likely in the poor connections. But, if you are using the ground at/of the bulb socket then you may actually have voltage but a bad ground isn't allowing the meter to "see" it.
FTE Legend
Joined: Jul 2010
Posts: 32,875
Likes: 48
From: Northeast, OK
I'd forgotten the fuse issue. Just went back and re-read - and I'm still not sure where things are. So, a couple of questions:
- What fuse is in it and is it holding now?
- What all has been tested and is now working?
pedant
Joined: Jan 2008
Posts: 23,576
Likes: 38
From: EXTREME southwest CT
Post #25???
A) He said 15A is holding, but with the rear light harness disconnected.
B) The front lights "work fine".
A wire is chafed through or crossed to ground, likely in a bad trailer splice or where the harness runs up into the corner of the bed.
A) He said 15A is holding, but with the rear light harness disconnected.
B) The front lights "work fine".
A wire is chafed through or crossed to ground, likely in a bad trailer splice or where the harness runs up into the corner of the bed.