1 (edited by Lemon_Newton-Metre 2022-10-13 08:20 AM)

Topic: Electrical diagnosis input sought

B.L.U.F.[edit: Bottom Line Up Front]:
Trying to figure out what's blowing the marker light circuit (20A).

Could an extra, loose, bare hot wire *** NOT in the circuit *** occasionally touching bare grounded metal (frame, body - somewhere) blow the circuit? And from what it appears, only THAT circuit?

Or (obviously more likely) worn insulation, faulty switch, or faulty LEDs IN the circuit? He'll have an *actual* mechanic look at it sometime; he'll just drive during the day until then.

'88 S10, multiple owners, aftermarket stereo installed, obviously removed, installed again/ different head unit, whatever, accessories & switches.

Rat's nest of wiring in the engine compartment and interior.

There's LED bulbs in the sockets on the four corners, that look mixed with two incandescent in the front bumper. I have a new switch on order (it's the separate lever design) to be delivered to him in SD.

I had only a short time to try to help this friend, so I did a little diagnosis / remediation, but I know for a fact I didn't fix the problem by just replacing the fuse.

I removed some wiring that was not connected - maybe 6 wires, at least two of which were hot, maybe two others switched hot, and two not connected to power anywhere. The problem again occurred after that removal.

I did a quick look for cut / worn insulation on the wires of the circuit and didn't find anything, but that was only what i could see from underneath or inside, without opening up things. That's where I have to think the problem exists, unless it's the switch or LEDs.

It appears there are still rubber grommets in several areas of the circuit.

But I didn't have much time - my friend intended to leave that day without fail.

More detail:

A friend purchased a vehicle from his friend at a small lot - with an on-site mechanic - that has some electrical problems. He's a full-time nomad.

He purchased this as an emergency replacement for his previous vehicle ('98 Dakota, ~180k). That vehicle he also purchased from this same friend, and wound up with spurious electrical problems, replacing the right front suspension and hub, and then the engine; and now his tranny blew along the highway in SD - and he can get it "looked at" in two months. Everybody is short-staffed.

I found a contractor's van for him on Copart, clean title, '97 B1500, 5.2l, 85k on the odometer (which works only occasionally, so I'm thinking around 130k), and after I replaced the dead battery, seized alternator, tensioner pulley, and belt, runs really well and shifts nicely.

I've already pulled newer seats for it, and it needs vacuum lines and a serious cleaning, but it'll work for him.

The S10 cost 4x what the van cost.

He has already started on his trip west for the winter, and then back east in the spring.

Any thoughts?

S10 Engine compartment:




S10 Interior:



Re: Electrical diagnosis input sought

Could be anywhere, but most tail shorts on trucks are trailer lights related, start at the trailer plug then go up under the bumper to the mess it connects to.

No trailer hitch? still look around the rear area first.

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3 (edited by Lemon_Newton-Metre 2022-10-13 08:20 AM)

Re: Electrical diagnosis input sought

The lights are on the back burner for now. Agreed the tail end would be a likely place to start; there's no trailer electrical left, though there may have been. Also agree it could be anywhere, especially with the - frankly - crappy wiring job previous owner(s) did.

So, he made it to SD in this truck also. His friend that sold the truck told him the engine had recently been rebuilt, so the 225k miles on the truck didn't faze him. Then there was some noise, and he got an indication of no oil pressure on the gauge, and the engine doesn't run right now. Had it towed to a mechanic in the same town his other broken truck is in.

The Dodge van is running pretty well; and if he can't get the truck fixed within budget right now, he'll fly back and drive the van.

He's agreed to stay in the east this winter until the van is a known item.