Wiring problems...

[TJ79Cheyenne]

Hey guys a couple weeks ago I was trying to start my truck. The all of a sudden there's smoke coming from under the hood. Turns out the ground from the battery the the front clip started melting. This is an 87 R10 TBI motor. It has never done this before I rebuilt and reinstalled the engine.. Well today I was tinkerin around and noticed 2 ground wires on the back of the passenger side head were exposed. I wrapped them up individually with electrical tape. As soon as I tried to wrap the 2 wires together to make sure they stayed unexposed I heard wires frying again. Turns out the wiring going to the starter was burning up and I dont know if I fried the starter solenoid. I guess my question is, has anyone ever had any issues with this? And what did you do to remedy the problem?? I just want to get this damn truck on the road again

 

[Boone83K10]

sounds like you popped the fusible links

 

[TJ79Cheyenne]

The fuseable links on the firewall? I hooked wiring up from the battery to that n turned the key on n it fried that wire too lol. Has to be a bad ground somewhere

 

[89Suburban]

There is a tubular heat shield above the starter that some of the wires go through, you could have some burned and grounding wires in there.

Fusible links are above the starter, on the firewall by the junction block, and possibly at the alternator.

 

[chengny]

Am I correct in saying - this is only happening when you turn the key to the start position?

Assuming that is the case, you most likely have a dead short to ground in the solenoid control circuit. More specifically, it is somewhere between the ignition switch and the "S" terminal of the solenoid.

If you have an automatic transmission, the power from the start contacts of the ignition switch first goes down to the neutral safety switch (NSS). The NSS is mounted at the base of the steering column - right near the firewall. Manual transmissions use a clutch safety switch instead of the NSS.

It is a yellow lead going into the NSS and a purple lead coming out. That purple wire then goes straight to the "S" terminal.

When the key is turned and the truck is in P or N, power passes through the NSS and is supplied to the solenoid.

I would concentrate on the purple wire when looking for the dead ground. And most likely (because you have recently pulled and installed an engne), the problem will be at the very end of the purple wire - down by the starter.

 

[TJ79Cheyenne]

Thanks guys youre givin me a couple good places to start. I'm not sure if the starter solenoid got completely destoyed when this happened. Ton of smoke was comin from it so I'm going to assume that it needs to be replaced. Yes the key was in the on position when this happened.

 

[chengny]

Yes the key was in the on position when this happened.

I thought you meant that you were trying to crank it over when the jumper wire heated up.

If the key was just in the RUN position - and not the START position - you can disregard everything I suggested about the purple wire.

 

[TJ79Cheyenne]

Update!

I was all ready to reinstall a new starter for the truck and I pulled on the wiring harness going to the starter. Found the fusible link and noticed that a bunch of the wiring was exposed. I dont know if it was like this before I was messin with those 2 ground wires or if I caused this problem when I was messin with them... Either way I'm probably gonna have to rewire it and I was just wondering how you guys did it.. I've never really messed with the fusible link before thats why I thought I'd consult with the experts haha. Could I use a 10 gauge connector and run the wires through that?

 

[chengny]

Undo the wires from the solenoid - if not done already - and pull the harness up through the steel conduit/heat shield. This will give you some room to work.

Crop out the sections of the wiring that are in poor condition (these sections will include the fusible links). The rating for those links are 14 and 16 amps (one each) - these ratings are a function of wire size and circuit load.

Refer to the diagram below. Get a couple of properly sized fusible links at any auto parts store (O'Reilly's is shown). Solder them onto the good ends of the wiring harness - soldering is highly recommended, don't butt splice them in.

Fish the wires back down the pipe, reconnect and go.

 

[TJ79Cheyenne]

Good call there. Didn't even think about pullin the wires up to the top of the motor to work lol. I've never done saudering before could be a learning experience coming soon lol. Thanks for replyin so quick man I was just out there getting soaked to the bone with all this snow crap melting