Electrical problems, I cant handle it on my own!

[Mark Hanna]

Hi everyone,
I have a 1972 c-10 that I have been working on for the past couple months. I put in a new transmission, radiator, brake booster mc, thermostat, u joints, starter, battery...pretty much everything she needed to get down the road, and I am now faced with my worst nightmare. I was driving the truck to the gas station to get some go go juice when all of the sudden she died. I figured she was out of fuel (since i think my fuel guage is non functioning), but after I got some gas in her, I tried to start her and nothing happened when I turned the key. No clicking from the starter or anything. This is a brand new battery that I have since put on the trickle charger. I can assure you that the battery is hot. I thought that maybe it was the battery cables, but just to be curious, i put a wrench on the large stud on the starter silinoid and it sparked and the starter spun over. But still nothing at the key. I am BY FAR electrically challenged and have no clue what is wrong. Could it be the ignition switch? Possibly a fuse (please be a fuse)? I am just overall disgusted by it and after putting so much money and time and effort into this ol girl I hate to get tripped up by an electrical problem. Any help would be greatly appreciated guys, and thanks in advance!

[72lb4x4]

There's a neutral safety switch to keep the starter from running when its not in parl or neutral if you have an auto on the column.

Since it was running, I'd guess that's a good spot to start.

[57larry]

check your battery cables, sounds like a bad ground

[dznucks]

do your dash lights come on or your radio, when you turn the key?


I had a similar problem that turned out to be the negative battery cable. I found it by connecting a jumper cable from the negative battery post to the frame.
Another time it happened, it was a bad splice in the wire going to solenoid that the PO put in.

There are alot of things that it could be.....but there are only a hand full of things to troubleshoot.

Since the starter turns over when you trip it, it sounds like it might be with the ignition switch, maybe a burnt wire around the manifolds, you may even have a loose connection somewhere. Dont be overwhelmed by electrical problems, its not that difficult.

[Classic Heartbeat]

A couple of good responces here. My first and cheapest suspect would be the Nutral Safety Switch. Try wiggling your shift lever around in park and see if the starter turns over.
Then check all four ends of your battery connections. (I doubt that it is there because you say you can jump the cylenoid.)
The next place to look id the stud on the right front fender. Your ignition switch gets its power to send to the starter cylenoid from there. Check that the little nut is tight and you are getting good contact.
Failing that, you could have buned the fusable link in the headlight harness. (For the same reason as above.)
The next thing to do is to wiggle the wires around at the firewall where they plug into the back of the fuse panel. (Possibility of a corroded or bad connection at that point)
There is also a chance that it could be your ignition switch. If everything above is not the problem then that could be your gremlin. WES

[RPBurris]

I am not an electrical genius either but it does sound like a grounding issue. You did say it died on the way to get gas so it was running and then it was not. I would double check all of your fuses and make sure you have a good ground. The neutral safety switch would not cause it to die while running.

[Longhorn Man]

need more info... do you have power to anything at all? Headlights, cigar lighter, brake lights?

[ERASER5]

Mark, yes we need more info to really be of help. And, as I am only maybe an hour away, I could possible come over to help, if needed. I am in Connersville. PM me if you need me.

[Mark Hanna]

Wow, thanks guys for the responses. Lots of good ideas here. The only other info that I can offer is that I do not have power to the headlights, brake or running lights or anything. And ERASERS, I thank you very much for your offer. If it comes down to it, I may take you up on your offer; it is very much appreciated.

My father mentioned the neutral safety switch, and I have wiggled the gear shift (column) in park while turning the key and that didnt seem to get me anywhere.

Since I have juice to the starter, would that mean that I have good connection at all 4 points between battery/groun/and starter? (see, this question proves how bad I am with anything electrical)

I will definately check for burnt wires around the manifold. That kind of makes sense because I am the idiot that took the motor out haha.

Where would the fusable link in the headlight harness be located exactly?

And just for clarification, yes, the truck died on the way to the gas station, but for what reason I cant say for sure. There is a slim chance that the truck ran out of gas and died, and then somehow developed an electrical issue, but my money is on the electrical issue causing the stoppage.

Again thank you all for your responses, I will keep you updated as I progress through this diagnosis and revival!

[72chevyk10]

a while after i got my truck i tried to start it one day and absolutely nothing happend. so being my redneck self i had a screwdriver with me and made sure i had power. i did. so the next thing i checked was the plugin thing to the key. i mashed the plug in real good and hit the key and it fired right up. so you might want to check that plugin to the back of the key

[gary2232]

Just to rule it out unplug the connector to the neutral safety switch located at the base of column at floor board and put a jumper in plug. That is what fixed min.

[fixit-p]

Originally Posted by Mark Hanna

I do not have power to the headlights, brake or running lights or anything.

X2, Sounds like fusible link............ If you look at the batteries positive post there should be 1 heavy gage wire going to the battery and a smaller gage wire going to a terminal block which should be connected to a red wire which provides power to the cab the fusible link will be on the smaller wire.

[72chevyk10]

Originally Posted by fixit-p

X2, Sounds like fusible link............ If you look at the batteries positive post there should be 1 heavy gage wire going to the battery and a smaller gage wire going to a terminal block which should be connected to a red wire which provides power to the cab the fusible link will be on the smaller wire.

oh i forgot about that part.. never mind what i said then

[Mark Hanna]

Okay, so will the fuseable link in the headlight harness be located on the drivers side near the core support or am I thinking wrong? And what does it look like?

[fixit-p]

Here you go

[Longhorn Man]

that link will disconnect EVERYTHING from the battery except the starter. Start there. Inspect the wire going across the core support, probably pinched.

[Mark Hanna]

Alright, so this diagram shows the link as being on the small red wire coming from the pos battery terminal between the battery and the little junction box on the passenger inner fender, correct? On my truck, that wire is solid and has no kind of link in it. It is pretty obvious that a previous owner has done some messy electrical work on this truck, so that just adds to my quandry.

[VetteVet]

Here is the basic power diagram for the chevy/gm cars and trucks. They moved the horn relay inside the cab by the fuse panel on the later trucks. You might try a jumper from the battery positive to the large terminal on the back of the alternator to see if you have an open from the small wire off the battery to the first splice. Use caution in case there is a short.

[Mark Hanna]

Okay everyone, I have found a little time to fiddle with my electrical problems, and upon further investigation, I may have found the problem. In these pictures, I show the 2 wires that go from the little junction post on the right inner fender to the harness that goes across the top of the core support. I think I found the fusable link, which was the little black plug thing in one of the pics. Upon un-plugging it, I broke the glass, so I will need a new fuse i suppose. Is this a commonly found fuse or do I need to special order it somewhere? The fuse "housing" came apart pretty hard, should it take that muck force to remove it? I don't want to break the new one when I put it in. The other wire had a wierd yellowish/clear connector on it, I'm not sure what that is for, but the portion of the wire between that wierd connector and the junction post had a hole in it and I could see corroded copper. Another thing I will note is that this portion of the wire also had a wierd rubbery, elastic like insulation, instead of the harder, more plastic type insulation on normal wires. I was inspecting this wire and when I was feeling it, I felt a part where the copper wire inside was not connected, so I just pulled it until it ripped apart. I will have to replace that wire and the fuse from the link now, and hopefully that will fix my problem. So am I going in the right direction fellas? Oh and just for fun, I also included a photo of the truck. I know she probably isn't the most beautiful thing to you guys, but she is beautiful in my eyes, because this ol girl was my first vehicle.

Thanks for all the help, by the way. It is very very much appreciated.
Mark

[fixit-p]

The wire with the funny insulation and splice is the fusible link make sure you replace it with fusible link wire or a slow blow fuse (maxi fuse works). The other glass fuse is for your ammeter
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[Mark Hanna]

Thank you, fixit. I searched Oreiley Auto Parts and found a few different fusable links. Some for ford, some chrystler. Would it be okay to use one of these? And also, will the glass fuse be commonly available at a store like Oreiley?

[VetteVet]

The glass fuse is a 4 amp and should be available anywhere. There are 2 of them in the harness and the other one is in the wire that goes to the three way splice for the alternator.