LilBeast

Hey All,
I recently purchased my first truck, a 1980 4x4, sitting on 35's, and in pretty darn good shape. It's sweet... I'll post pics soon.
It has one problem that I need help with. When I bought it, the tail lights, dash lights (that light up the speedometer, oil gauge, etc), all parking lights, and license plate lights don't work. The brake lights, headlights, turn signals (including the little arrows in the dash), and hazards all work normally.
Basically the fuse for "TAIL" breaks immediately when inserted. When I put one in, the wire in the fuse cylinder looked like it fried, not just broke like normal. All the non working lights are related to this fuse.
I know this means there is some sort of short.
I really don't know what my best bet is as far as finding the problem, and I don't want to pay an electrical specialist. I can't legally drive it because I need to pass a Safety Inspection here, which means these lights must work.
What do I check first? It seems like it should be a simple situation... just one problem somewhere causing all this trouble.
Thanks in advance for your help!

LilBeast

Oh, this is my first thread... its a 1980 so I posted it here, but if it would be better in the electrical/lighting section, moderators, please feel free to move it. Thanks!

muddpigg

iTrader: (1)

You need to run the wires going to the tail end. You might want to start looking at the ends perhaps you'll get lucky but you may need to see the whole length of wires.

Welcome to YT. Sounds like a nice score on the truck just needs some TLC. At that age all trucks need TLC.

eric-the-red

If it has a trailer light connector installed that's the first place I would check. Just disconnect it abd see if that fixes the problem. If not then remove the rear light assemblies and the front parking lights and check for corrosion, on a 1980 there's sure to be some. Also look for broken wires or missing insulation in there. If that doesn't fix it then as muddpigg said you'll have to check all the wiring.

You say the fuse blows as soon as it's inserted, is that after the lights are turned on or immediately even if the light switch is off. If it's the latter then the problem is between the fuse block and the switch.

LilBeast

Thanks for the responses so far. I don't think there is a trailer connector attached, but I'll double check. And I believe I did say it wrong... I am pretty sure the fuse burns as soon as I turn on the light switch, not before. I am going to head out to the truck right now and double check that, then I'm going to remove the assemblies for the tail lights and front parking lights. I'll look for any corrosion or freyed/exposed wires. I'll also look closely at the bulbs to be sure those aren't causing the problem. I'll update shortly.
Thanks again!

LilBeast

Okay, so it does only blow when the light switch is turned on. I took a good look and may have found the culprit... but now need help on what to do.
There is one plug that goes from the cabin to the bed, which runs the power back to the tail lights. That plug is there, and is fine. It's just behind the passengers seat. Now, follow that wire forward under the carpet along the passenger door, and I found that the wire colored Red with a light blue line (the only red one in the group) not connected to anything. It was pulled at some point. There are three or four green wires, a yellow, and this red with blue line coming out of the plug. The red with blue line is disconnected behind the glove box, but the only wire that is hanging there coming from the other end also not connected to anything is a solid light blue. See the pic. I haven't tied the two together, since I don't know if it's supposed to be that way and I don't want to ruin anything else. I did make sure each (the red with blue stripe and solid blue) weren't touching anything at all, and tried a new fuse, and it still blew immediately when I turned the lights on. So it must be whatever is on the closer to the fuse side of this pulled apart wire. I think the actual lights in the back wouldn't get any power at all because of this regardless of the fuse, and whatever that red wire is supposed to be connected to is causing a short. What does it connect to? Does it go to that blue? That doesn't look right... See the pics... Maybe someone wouldn't mind looking at theirs and seeing what it's supposed to look like.



(ive never posted pics on a forum, not sure if it worked...
here they are though...
http://imageshack.us/photo/my-images/690/redwire.jpg/

http://imageshack.us/photo/my-images/90/plugtobed.jpg/

Thanks for your help!

LilBeast

Okay, another update... that red wire is for the reverse lights, which also don't work. Separate issue, but that's why those dont work. Now, I unplugged that plug behind the passenger seat to see if the fuse would still blow. It did, which means the problem/short is between the fusebox and the plug, right?

eric-the-red

Correct. Actually if the fuse blows only when the light switch is on then it's somewhere between the switch and the plug.

LilBeast

Got it... at least the entire rear of the truck is eliminated as far as where the problem might be. The challenge is that there is so much of this in the front, branching all the way up to each front running light. Since the fuse blows and I can not keep a current going, I'll have to figure out how to check each socket/plugs integrity. There are no obvious cuts or places where the positive wires are grounding. So much of the wires just disappear into the stock harness, so I have to figure those are fine if they are just taped up with no sign of being disturbed.
I'm heading outside to get back on it.

truckman1966

look for chafed wires that are shorting to ground. sounds like you are on the right track