Wiring help

[Stephen717]

So I got my engine bay wired and as far as I know everything is hooked up right. The only thing I noticed was that during the wiring process I didn't hook up the junction block or fusible link. I figured since the truck was running fine without it when I rewired it it wouldn't need it. but now when I turn the key I don't here any indication of the truck even remotely trying to start. can anyone tell me where I went wrong.

thanks,
Stephen

[ray_mcavoy]

The junction block near the battery & fusible link connecting it to the battery provides the main electrical feed to the truck. Without that hooked up, everything will be completely dead.

It sounds like the previous wiring must have had some sort of alternative wire in place (perhaps connected to the positive battery cable down at the starter solenoid) that was serving as the main feed to the truck's electrical system.

[Stephen717]

Thank you for your info. I have the junction block from the guy I bought the truck from. He just had it sitting in the glove box. Probably forgot it was there. I'm guessing it needs to connect to the positive terminal. What needs to be connected to it? Starter, alternator? I'm honestly confused. Any help would be much appreciated.

Thanks,
Stephen

[kwmech]

The junction block is just that.. a place to hook the wires up. What did you do with the red wire (12 ga) coming across the core support to the battery side?

[ray_mcavoy]

Originally Posted by Stephen717

Thank you for your info. I have the junction block from the guy I bought the truck from. He just had it sitting in the glove box. Probably forgot it was there. I'm guessing it needs to connect to the positive terminal. What needs to be connected to it? Starter, alternator? I'm honestly confused. Any help would be much appreciated.

Thanks,
Stephen

Yes, as kwmech said, there should be a 12 gauge red wire in the section of harness that runs across the radiator support. That red wire is the main feed / battery charge wire. It was originally connected to the junction block. And then a section of 16 gauge fusible link wire made the final connection from the junction block to the positive battery terminal.

I think there were a few years that had a regular (non-fusible link) wire running from the positive battery terminal to the junction block. Then the fusible link wire running from the junction block to a factory inline splice joining it to the 12ga red wire. Either setup will work. Just try to keep the length of the fusible link wire somewhere in the 6" to 9" range.

Also, if your truck was originally equipped with the factory gauge cluster (not warning lights) there will also be a smaller gauge black wire in the harness that runs across the radiator support. That wire leads back to one side of the battery gauge (ammeter) and was originally connected (through a 4 amp inline fuse) to the junction block.

[rjs53]

Originally Posted by ray_mcavoy

Yes, as kwmech said, there should be a 12 gauge red wire in the section of harness that runs across the radiator support. That red wire is the main feed / battery charge wire. It was originally connected to the junction block. And then a section of 16 gauge fusible link wire made the final connection from the junction block to the positive battery terminal.

I think there were a few years that had a regular (non-fusible link) wire running from the positive battery terminal to the junction block. Then the fusible link wire running from the junction block to a factory inline splice joining it to the 12ga red wire. Either setup will work. Just try to keep the length of the fusible link wire somewhere in the 6" to 9" range.

Also, if your truck was originally equipped with the factory gauge cluster (not warning lights) there will also be a smaller gauge black wire in the harness that runs across the radiator support. That wire leads back to one side of the battery gauge (ammeter) and was originally connected (through a 4 amp inline fuse) to the junction block.

I have the same issue, this info was exactly what I needed. Thanks

[Stephen717]

would it be possible to see some pictures of what you are talking about? I want to make sure I know which wire is the correct wire to move before moving anything. as right now the wire that I think you are talking about I have running all nice and hidden away going to the starter. foolish move on my part if this is the wire that runs to the junction block but it was the first time I've ever wired anything and everyone is capable of making mistakes. also what size fuse would I need to run?

Thanks for all the help so far,
Stephen

[ray_mcavoy]

Take a look at your wiring harness near the passenger side headlight. The red feed / battery charge wire originally emerged from the wiring bundle near that location.

Here's an old pic of the junction block on my '72. Unfortunately, it's not the best at showing where the wires all lead off to and the truck isn't very accessible at the moment (lots of snow blocking the garage doors). But the red wire that goes out of frame near the bottom of the pic is the one that connects to the positive battery terminal. The small black wire with the rubber inline fuse holder is for the ammeter. And the remaining wire is the fusible link. Just out of frame of the pic to the left is where it has a factory splice (covered by a round plastic insulator) joining it to the 12ga red wire. And that 12ga red wire (along with the black ammeter wire) were originally bundled into the harness along with the passenger side headlight wiring running across the radiator support. Hopefully someone else will have a better pic.

[Stephen717]

Ok so I'm like 90% positive that that's the same wire, and I probably should have mentioned this before, but I ran all the wires through a grommet and under the dash so they would stay hidden and the engine bay would be just a bit cleaner. I still have enough wire run to take it off the starter and move it to the junction block. I am surprised that it can't be bypassed though. As the way I currently have it wired is with the positive from the alternator to the positive lug of the starter and the main feed wire running to the same positive lug. Then I have the positive battery cable running to the starter and the ground wire going to the engine. I figured with the engine being grounded to the cab and the cab being bolted to the frame everything should be grounded good. I will rewire it so the main feed goes to the junction block and see if that helps. Also do I need the ammeter wire that runs to the junction block if I plan on switching to a volt meter? And does anything else need changed? Again thanks for all the help. I'm still figuring all this out.

[ray_mcavoy]

So if I'm reading that correctly, you have basically just re-located that 12ga red wire so it is now connected to the large BAT stud on the starter solenoid (along with the positive battery cable), correct?

If so, that should be functionally equivalent of having it running to the positive battery terminal via the junction block. So you probably don't have to go to all the trouble of changing it around. I would recommend adding a fusible link (or fuse) back into the main feed wire (near where you have it connected to the starter) to protect the wiring in the event of a short. But other than that, the setup you have described sounds like it should work (and is very similar to what GM did in the later 70's/80's trucks).

At this point, I'd recommend double checking all of your connections and using a test light or voltmeter to verify that you have power on the main feed wire into the fuse panel & ignition switch.

Also, when you were re-doing the wiring, did you happen to have the under-hood harnesses unplugged at the firewall bulkhead connector? If so, you might want to check that over to make sure a terminal didn't come unseated and get pushed back out of the connector when it was plugged back in.

[Stephen717]

Thanks for informing me that me screw up was semi correct. I will add in the fuse in the morning and check all start checking all the connections again as my truck is at my family's shop. Now to go off topic just a bit. Has anyone used the H6024 Dual Beam Sealed Beam LED Headlight Conversion Kit from headlight experts? I want to go this route as they look really good and they're the only glass dome led headlights I've found so far. But I don't want to waste my money if it's not a good product. Any info would be greatly appreciated. Thanks for all the knowledge and help so far.

[Stephen717]

IT'S ALIVE! Well, sorta. I still have to get a throttle cable and I need to put gas in it. But the old girl finally turns over. Could you believe I over looked the neutral saftey switch wires. Re read the instructions and it said to hook them together when using a manual transmission. Now she turns over and sounds healthy. I'm glad to hear it again after well over a year.

[Stephen717]

So to update. Got a universal Mr. Gasket throttle cable and cut it down to work. Used a drum brake spring as linkage from the carburetor to the linkage. put 5 gallons of gas in it and heard it run for the first time in over a year. She still has the inline tractor sound. Tomorrow I am going to take the fuel line off the pump as I suspect a bad fuel pump. I am also getting 5 more gallons of gas from the local gas station to put in the tank. If the fuel pump is bad I will pick up a new one. I am also paying for the new (to me) bed and am looking at a tailgate and LED headlights after the first of the year. I am also looking at putting in a hanger to hold the exhaust up and am temporarily putting a used Flowmaster super 10 muffler on it from my wrecked 97. Since it has a homemade two and a half inch exhaust I don't really care if it is cobbled together. That's all for now.

[Stephen717]

She's fully running and moving under her own power. I have the wipers working the engine bay is fully wired. And the cab is halfway. Not going to wire the back until I have the new bed for it and can afford to get tires so it's street legal. 10 year old tires aren't the safest but they're fine for putting up and down the back road that our shop is on.