GM Wiring Harness

[trbankii]

The PO of my truck pretty much butchered the wiring harness at the rear of the truck. The chassis harness comes back to the plug, there is a T-plug going to a 7-pin trailer harness, and then the other plug going to the taillights.

It looks like there were at least three (maybe four) other trailer harnesses spliced into the 7-pin harness and the taillight harness and then the wires were cut back off - leaving all these little stubs. When I pulled the plugs apart, they were so corroded that a number of the pins broke off. Passenger side backup light isn't getting power and some of the other lights are a bit flakey.

So my thought was to just start clipping things apart and soldier stuff back together. However, the wires seem to be coated with something that is keeping me from soldiering them at all. Now I've been soldiering since I was kid - Heathkit and Radio Shack kits and all of that. Is this something particular to GM wiring?

[DmaxMaverick]

I've soldered several of the wires on my '01, including the rear lighting and trailer harness. I didn't notice anything out of the ordinary, and GM hasn't released any bulletins recommending special handling with wire repairs.

I would suspect serious salt contamination, evident by all the corrosion you found. Copper can be so corroded it will not take to solder, even with a very aggressive acid flux. The only course at this point is to replace the wires. Once the corrosion reaches the point the copper is brittle and won't take solder, it's too late. As a temporary measure, you can clean and crimp connections, but it won't last long.

[trbankii]

That sounds like the situation, because the wire was also brittle like you mention. I'm a little surprised that it traveled back that far. I cut off a bit from the affected areas and then stripped fresh wire.

Have to do some more exploration to figure out what I'm going to do.

[Turbo Al]

I know Painless sells a complete harness for your year of truck but it is quite $$$.

[trbankii]

I'm not to that point... smile.gif

Really, I think that if I cut the chassis harness back a few inches from the plug and likewise for the taillight harness, I should have good wire. If the corrosion goes that far back then we're in trouble.

Just have to find an afternoon to tear at it.