Wiring issue.....Weird problem to me

[kidego31]

Getting my truck put back together and this seems like a weird problem but I guess it could be normal.

The harness in my engine cavity is hacked up by the PO. When I first tried to see if the truck would crank I had no power to the ignition. Turn the key and nothing. I probed all kinds of wires and had power under the dash. Got frustrated and decided to take a break from that aspect and get the alternator, power steering pump and all the stuff on the front of the motor bolted on.

Got everything bolted on and hooked up and all of the sudden the truck would crank and fire up. Once the truck fired up had a nice little cloud of smoke come out of my alternator. Yep it was fried. So unhooked the number 1 and 2 wires from the alternator and no power at the key.

So Is it normal that when the plug for the alternator is not plugged in that it will not crank. I can plug the wires back in and boom it cranks. The PO has the red wire at the plug spliced into one of the wires at the starter..

Trying to figure this out before I smoke a new alternator.

Little more about the PO is when I pulled the motor there was not one single ground strap was hooked up. When I got the motor back in I hooked the 2 back up that were just hanging there. One went from the cab to the motor and the other went from the motor to the frame.

Wiring is the biggest weak point I have when it comes to cars. Any help would be great. I have been searching online for a new or used engine compartment harness but have not had a lot of luck

 

[Customblue]

This doesnt answer your question but, I installed a universal wiring harness from painless wiring in my truck and it worked out well. I hate wires as well...

 

[MikeB]

Getting my truck put back together and this seems like a weird problem but I guess it could be normal.
So Is it normal that when the plug for the alternator is not plugged in that it will not crank. I can plug the wires back in and boom it cranks. The PO has the red wire at the plug spliced into one of the wires at the starter..

First of all, by "crank" do you mean turn over or start?

But either way, that's not normal. One of the small gauge alternator wires is the "sense" wire, which is tied to some central point, like the distribution block on the firewall. That's where the alternator "senses" system voltage and tries to keep that point at 14.2 volts. Some guys, or even aftermarket harnesses, will connect that wire to the large red charging wire on the alternator as a shortcut, but that doesn't take into account any voltage drop across small wires and poor connections. So the alternator could be fat, dumb, and happy putting out 14.2 volts, but voltage at the distribution block and battery might be only 13.5 or less.

The other small gauge wire is the "exciter" wire that starts the alternator charging. It will be connected to the IGN bus through the ALT idiot light. With a voltage gauge it's a little different, but I don't recall how. Maybe just straight from alternator exciter terminal to ignition bus.

The ignition wire that powers the HEI (or coil) comes directly from the ignition switch. The ignition switch itself should be fed by a large red wire that's comes from the fuse panel BAT bus. The BAT bus itself is fed by 1 or 2 large wires that are tied electrically to the alternator output wire and the starter's battery terminal. On my 82's stock harness, there were two fuse panel feed wires that were physically connected to the BAT terminal on the starter through fusible links.

 

[MikeB]

This doesnt answer your question but, I installed a universal wiring harness from painless wiring in my truck and it worked out well. I hate wires as well...

I did the same thing, and it was not a trivial job. I did make several modifications, such as feeding the fuse panel with an 8-gauge wire. I also found wiring the instrument cluster and the wiper/washer to be a real bitch. Mostly just trying to understand the factory schematics and connector pin-outs. And heck, this was my 3rd or 4th wiring harness job! Give me a 50s to early 70s vehicle any day!

8 gauge from battery/alternator to two 10 gauge wires to feed BAT bus and ignition switch.

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[gmachinz]

That’s why I build custom or stock reproduction style factory harnesses-I hate the universal versions.

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[MikeB]

Looks good.

Please chime in here. I'm sure the OP can use more advice.

 

[gmachinz]

Hard to say what direction to take w/o knowing exactly what kind of shape its all in.

 

[kidego31]

That’s why I build custom or stock reproduction style factory harnesses-I hate the universal versions.

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How much do you charge for a harness? I went through and found wire that are cracked and wires exposed.

 

[gmachinz]

What harness are you referring to? Sorry I’m so late to reply-I’m all over FB but I just don’t get around to message boards much anymore lol

 

[gmachinz]

If anybody needs to reach out:

https://www.facebook.com/Harnessworx