New tranny and now I have wiring issues?

[Jayred]

After getting into all the wiring two wires have melted and taken out some others. My 12r from the fuse block by the battery has been spliced by the driver headlight and after it is spliced it is melted all the way back to the fuse block. There is a brown wire I think it's 12BRN that is melted from the fuse block to the back of the ignition switch. Also from the back of the ignition switch is a red wire that is melted, but I can't find it in the wiring diagram. It looks like 12BRN is used for the front flashers and those wires are melted and frayed in the loom up front behind he tail lights. I'm assuming that is where my short is and it fryed the 12BRN and 12R. If those were fused I don't understand why it shorted though? Wouldn't it have blown a fuse? I'm going to replace the melted wires with overlay wire and resplice wires that were damaged nearby. What a cluster. Whoever had the truck before me added so many new accessories, I'm afraid is overloading everything.

[VetteVet]

In order to understand how this happened it is helpful to know how the wiring is set up and the direction of current flow. Electricity flows from positive to negative so the direction of current flow would start at the positive terminal of the battery and flow through the fusible link to the terminal on the right fender. It is a junction not a fuse block however your fusible link should have blown, if it had one.

Here is a view of the factory routing of the wiring showing the 12R wire by the battery and the splice you refer to by the left head light.







If you follow the 12R from the splice it goes to the firewall block into the cab where it makes a junction with the other 12R wires that feed the fuse block, the horn relay, the headlight switch, and as you can see the one going up is the one you questioned that goes to the ignition switch. When the switch is turned on, this 12R hot wire feeds the 12BRN which returns to feed the turn signals and hazards,along with the wipers and the heater switch.

This is visible in the first diagram above and in this one showing the key switch wiring.

Originally Posted by Jayred

After getting into all the wiring two wires have melted and taken out some others. My 12r from the fuse block by the battery has been spliced by the driver headlight and after it is spliced it is melted all the way back to the fuse block. See the first diagram

There is a brown wire I think it's 12BRN that is melted from the fuse block to the back of the ignition switch. Also from the back of the ignition switch is a red wire that is melted, but I can't find it in the wiring diagram. Both are shown in the second diagram.

It looks like 12BRN is used for the front flashers and those wires are melted and frayed in the loom up front behind he tail lights. I'm assuming that is where my short is and it fryed the 12BRN and 12R. If those were fused I don't understand why it shorted though? Wouldn't it have blown a fuse?

The brown 12 R feeds the flashers which run through the turn signal switch and are not fused.
I'm going to replace the melted wires with overlay wire and resplice wires that were damaged nearby. What a cluster. Whoever had the truck before me added so many new accessories, I'm afraid is overloading everything.

You certainly should install a junction block in place of the spliced 12R wires and take your accessorie feeds off that. Replace the alternator with a CS144 100 plus amp model, and use an 8 gauge power feed wire from it to the junction, and you will be much better off.

Here is what I started with on my truck. It's the splice you mentioned.



And here is what I ended up with which is not completely done.

[Jayred]

Thanks for all the help! Gonna spend a few weeks taking it slow and doing everything right.