75 k10 wiring harness help. Plz

[DRCKISS]

I have a 75.k10 that I installed a 350 in amd none of the bulkhead wire.colors.matxh and online diagrams. I have no power anywhere ,no lights or juice at the fuse box. Ive connected and reconnected wires to the junction block and starter with nothing happening, can someone.please try to tell.me what wires.go where from my.pic


Thanks

 

[legopnuematic]

Start here: 1975 wiring diagrams

If you have no incoming power check the fusible links.

 

[CalSgt]

I have a 75.k10 that I installed a 350 in amd none of the bulkhead wire.colors.matxh and online diagrams. I have no power anywhere ,no lights or juice at the fuse box. Ive connected and reconnected wires to the junction block and starter with nothing happening, can someone.please try to tell.me what wires.go where from my.pic


Thanks

First off make sure you hooked up the grounds and they are secure... Batt to alt bracket or block, block to frame, back of head to cab Etc.

Batt positive is hooked to starter lug with the additional red wires, the purple wire should be on the "S" terminal of the starter solenoid

The two heavier gauge red wires on the bulkhead provide all power to the separate circuits in the truck, It is not uncommon for the spade terminals inside the bulkhead for these two terminals to burn up. It should be evident if you disconnect the bulkhead and look for the pins that correspond to the wire locations, the pins may be damaged or missing entirely or may have melted the plastic away from the terminals. If the pins are there check each of them for voltage.

If no voltage Those wires have a few fusible links in them at the junction block on the firewall (left of brake master cylinder) and at the batt lug of the starter, one of those wires may also be on a 'Y' with one leg to the batt lug on the alternator.

The red and purple wires often get discolored due to heat and time, they may be any variation of red-pink-purple or even yellow but if you trace them back into the harness a short distance the color gets better (usually).

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[DRCKISS]

First off make sure you hooked up the grounds and they are secure... Batt to alt bracket or block, block to frame, back of head to cab Etc.

Batt positive is hooked to starter lug with the additional red wires, the purple wire should be on the "S" terminal of the starter solenoid

The two heavier gauge red wires on the bulkhead provide all power to the separate circuits in the truck, It is not uncommon for the spade terminals inside the bulkhead for these two terminals to burn up. It should be evident if you disconnect the bulkhead and look for the pins that correspond to the wire locations, the pins may be damaged or missing entirely or may have melted the plastic away from the terminals. If the pins are there check each of them for voltage.

If no voltage Those wires have a few fusible links in them at the junction block on the firewall (left of brake master cylinder) and at the batt lug of the starter, one of those wires may also be on a 'Y' with one leg to the batt lug on the alternator.

The red and purple wires often get discolored due to heat and time, they may be any variation of red-pink-purple or even yellow but if you trace them back into the harness a short distance the color gets better (usually).

You must be registered for see images attach

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So is there not a certain wire that powers the fuse box?

 

[75gmck25]

Yes, there is a specific power wire, but you need to start at the battery and work forward.

Look at the pictures in post #3
- at starter - large cable from battery to the starter post. Make sure you have power at that post, and that the two smaller wires are firmly connected
- go to the firewall junction in the 2nd picture and check the smaller wire for voltage at the end where it connects to the junction block. If no power at that end, then you have a broken wire or a blown fusible link.

If you get power at the junction, but not at the fuses, then it’s a broken power wire to the fuse block, or a bad connection at the fuse block

 

[CalSgt]

So is there not a certain wire that powers the fuse box?

Two certain wires… They’re red and about 10 gauge or so.

This picture says for LS swap but still has the same red wires.

The one on the top left and fourth wire down near the left supply 12v to everything except the starter.

Inside the fuse box they get split into a few different circuits.

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[CalSgt]

I’ll add…

The top left wire in your photo looks like it has been hot enough to start melting the plastic. That’s an area I would inspect.