Ignition switch popping fuses

[jleblanc06]

So I've been working on my truck today, trouble shooting an idle issue and getting the timing better. Well I set the timing and turned off the engine and unplugged the battery.

Wait a few minutes and plug battery back in and try to fire it. Just one click and everything dead.

I locate a red wire on my battery which has a 30a fuse blown. I replace the fuse check everything and try the ignition, instant blow the fuse again.

So I trace the wire into the cab (Clearly installed by P/O not factory in any form) It go into a blue plastic plug that also has a purple and a pink wire. It goes to the top of the base of the steering column. Im assuming this is the ignition wiring.

What would make it start blowing that fuse?

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[1987 GMC Jimmy]

If I understand correctly, you've likely got a short to ground in that homemade ignition circuit. It's just a lone wire coming from the battery with an inline fuse that goes to your ignition switch, and that's the one that's blowing, right? It's not your fault, but when you disconnected the battery, you may have put that wire in a positon where an exposed section was touching something it shouldn't after you got it all hooked back up. I'd examine it closely, especially fairly close to the battery. I'd make sure the connections at the battery are good, too.

 

[jleblanc06]

If I understand correctly, you've likely got a short to ground in that homemade ignition circuit. It's just a lone wire coming from the battery with an inline fuse that goes to your ignition switch, and that's the one that's blowing, right? It's not your fault, but when you disconnected the battery, you may have put that wire in a positon where an exposed section was touching something it shouldn't after you got it all hooked back up. I'd examine it closely, especially fairly close to the battery. I'd make sure the connections at the battery are good, too.

Ok that’s what I was thinking as well. I’ve been looking under the dash though. I start at the battery. I have found some scary **** under the dash.

I appreciate all your help, I think you have single handedly kept my truck running.

Here’s a photo of something scary I found. Prob not related to my issue but cringe worthy.

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[Rusty Nail]

Bad.Ass!

 

[1987 GMC Jimmy]

Ok that’s what I was thinking as well. I’ve been looking under the dash though. I start at the battery. I have found some scary **** under the dash.

I appreciate all your help, I think you have single handedly kept my truck running.

Here’s a photo of something scary I found. Prob not related to my issue but cringe worthy.

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Citing factory wiring schemes, that maybe the wiring for the door lock switches. If you're having problems with those, fixing that might remedy that issue. And you're welcome. I hope the tricks and advice that I've learned get you somewhere in fixing the idiot PO's stupid ****, and you get the truck running well. You'll get it taken care of. You just have to keep at it and keep an open mind because sometimes it won't be an open an shut problem with a clear solution.

 

[jleblanc06]

Citing factory wiring schemes, that maybe the wiring for the door lock switches. If you're having problems with those, fixing that might remedy that issue.

I hacked off the added on wire and got it healed back up. Haven't checked the door locks yet (Which haven't worked right). still trying to get the fuse from blowing, so far no luck. Im thinking the issue may be the wiring at the starter. Its just so hard to tell where to start, the previous owner did sooo much random stuff I'm struggling to follow. He added CB, Light bar, winch, cd player but none of it makes any sense. Im just removing everything not essential i can redo it all later properly, I just need a running truck

 

[1987 GMC Jimmy]

If it were me, I'd strip all that crap out and restore it back to the factory harness, ignition circuit included. There probably wasn't anything wrong with it in the first place; he probably just tapped into the factory circuit to feed one of those gadgets and half ass rewired the ignition. I'll be honest with you. If I wanted CB, I'd just get a Delco 2700 AM/FM/CB, which these trucks could be optioned with, it would be a clean install, and that wouldn't ****** the factory harness at all. If I wanted a winch, it could cleanly be wired off the truck. The rest of it is just garbage to me. I'm not sure where to point you to in order to correct that problem. I'd just trace it as much as I could while being mindful of the areas where it could be shorting to ground.

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[jleblanc06]

If it were me, I'd strip all that crap out and restore it back to the factory harness, ignition circuit included. There probably wasn't anything wrong with it in the first place; he probably just tapped into the factory circuit to feed one of those gadgets and half ass rewired the ignition. I'll be honest with you. If I wanted CB, I'd just get a Delco 2700 AM/FM/CB, which these trucks could be optioned with, it would be a clean install, and that wouldn't ****** the factory harness at all. If I wanted a winch, it could cleanly be wired off the truck. The rest of it is just garbage to me. I'm not sure where to point you to in order to correct that problem. I'd just trace it as much as I could while being mindful of the areas where it could be shorting to ground.

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Ive already ripped it all out, no winch, no cb, no light. I don't need any of that crap. Just following through the wiring and removing anything that isn't factory or needed. But at this point i just got to figure out what is causing this new issue. The more I look the more depressed i get, its a MESS

 

[jleblanc06]

Alright so I'm going to have to better understand my wiring to figure this out because i haven't found anything obvious so far.

The fuse does not burn out with the ignition on, but as soon as i turn the key to crank, i hear it pop. This is the home made wire running from my battery straight to the ignition, it has a 30a fuse near the battery, this is the fuse that blows as soon as i turn to crank.

So when i turn the ignition key to crank,doesnt that release 12v from the ignition and send it to the starter solenoid to engage it? could my issue be that direction?

 

[75Monza]

Just curious, you said you were messing with timing, possibly bump some wiring running behind the distributor at the firewall, the stuff that drops to the starter? Also, you have headers? Place I've had the most issues with in the past on GM is wiring dropping to starter right at the bellhousing (manual)/block where it dives behind the exhaust manifold or header tube. But, being you have the curse of redneck U PO wiring job, who the hell knows, lol. My 86 was that way when I first got it, spent a day and tore out everything non-factory and started from scratch. Had almost a 30 gallon garbage bag full of wiring, old relays and switches, abandoned alarm system and stupid under dash led strips by the time I was done.

 

[jleblanc06]

Yeah I've been looking around the distributor just am not finding anything out of order. I do have headers and it looks like theres a few wires diving behind them straight to the starter, that is the next place ill be looking.

 

[jleblanc06]

MAY HAVE GOT IT! maybe...

so I was checking the connections at the starter, I noticed the main power lead from the battery to the starter didn't have power. I followed it back up and discovered it wasn't actually connected to the battery terminal, it was just being held in place by the heat shrink.

So I'm thinking since it wasn't getting enough power it was trying to pull from the ignition side which obviously couldn't keep up and instantly blowing that fuse???

that does that make any sense?

 

[RustyPile]

Ok Justin.. Replacing the blown fuse, running around to the key and turning it and blowing another fuse is not getting you anywhere.. It's time to change the approach..

Here's what you should do now.. For testing only, not as a permanent "fix" replace the fuse with a 25 - 30 amp circuit breaker.. Although it plugs in right where the fuse goes, I suggest you use a couple paper clips and short jumpers. Plug the paper clips in the slots for the fuse.. Connect a jumper to each paper clip and then connect the other ends to the terminals on the breaker.. On the load side of the breaker, connect your test light.. The light will allow you to monitor the off/on condition of the circuit breaker. When you turn the key to START, the breaker will go through cycles of "trip", "reset", "trip", "reset"...... Next, since the fuse blows only when the ignition is in the START position, Disconnect the purple wire at the starter solenoid.. NOW, you can turn the key again to START and watch the test light.. If the breaker continues to cycle off, on, off, on, the short is somewhere in the purple wire.. If the cycling stops, the short is in the starter solenoid -- replace it...

 

[jleblanc06]

Ok Justin.. Replacing the blown fuse, running around to the key and turning it and blowing another fuse is not getting you anywhere.. It's time to change the approach..

Here's what you should do now.. For testing only, not as a permanent "fix" replace the fuse with a 25 - 30 amp circuit breaker.. Although it plugs in right where the fuse goes, I suggest you use a couple paper clips and short jumpers. Plug the paper clips in the slots for the fuse.. Connect a jumper to each paper clip and then connect the other ends to the terminals on the breaker.. On the load side of the breaker, connect your test light.. The light will allow you to monitor the off/on condition of the circuit breaker. When you turn the key to START, the breaker will go through cycles of "trip", "reset", "trip", "reset"...... Next, since the fuse blows only when the ignition is in the START position, Disconnect the purple wire at the starter solenoid.. NOW, you can turn the key again to START and watch the test light.. If the breaker continues to cycle off, on, off, on, the short is somewhere in the purple wire.. If the cycling stops, the short is in the starter solenoid -- replace it...

Did you see my post above? I’m gonna get that fixed, if I still have the issue I’ll do you advice next. Thank you!

 

[RustyPile]

Well Justin, looks like we posted at the same time.. I'm not sure what you mean by "main power lead", but if you mean the large battery cable going to the large post on the starter solenoid, the answer is "no".. The big cable carries the current for running the starter, and the solenoid is just a heavy duty switch that carries all that current.. Unless your PO connected a wire coming from somewhere else to the battery terminal on the solenoid, the only thing that will happen is the solenoid will pull in but the starter won't run..

With the total hack job that's been done to your truck's wiring, you may have to engage the hands on help of a knowledgeable person.. Only so much can be done through the internet......