Wiring Fun

[justacruzr2]

Allright, this is a tuff one. Anybody know what the difference between an '84 GP and '86 GP instrument panel wiring harness is? I called a local dealer to get part numbers hoping that they both use the same loom but they don't. The '84 uses part number 12049287 and the '86 uses 12058047. The instrument panel instrumentation is no different between the 2 cars. The reason I'm asking is that I wanted to swap the '84 harness into the '86. Someone had been behind the instrument panel before and chopped some wires to put in an aftermarket stereo. They aslo did something with the dome and courtesy lights. When I removed the instrument panel someone had joined the 3 white wires which feed the door switches and dome light to another white wire which I'm assuming is the feed. It was soldered, glued and taped....not the way the factory would have done it. And they don't work. I did put a meter on the wires to check for continuity and the wires are ok and when I push the door switch in the meter goes to zero just as it should. So because there are several issues with the '86 wiring harness I was just going to swap the '84 into the '86. But now I'm not sure based on the different part numbers. Can anyone help with this?

 

[fleming442]

84-85 was the major wiring change. Your best bet is to score an entire harness, in and out, for whatever you're trying to accomplish.

 

[mikester]

Allright, this is a tuff one. Anybody know what the difference between an '84 GP and '86 GP instrument panel wiring harness is? I called a local dealer to get part numbers hoping that they both use the same loom but they don't. The '84 uses part number 12049287 and the '86 uses 12058047. The instrument panel instrumentation is no different between the 2 cars. The reason I'm asking is that I wanted to swap the '84 harness into the '86. Someone had been behind the instrument panel before and chopped some wires to put in an aftermarket stereo. They aslo did something with the dome and courtesy lights. When I removed the instrument panel someone had joined the 3 white wires which feed the door switches and dome light to another white wire which I'm assuming is the feed. It was soldered, glued and taped....not the way the factory would have done it. And they don't work. I did put a meter on the wires to check for continuity and the wires are ok and when I push the door switch in the meter goes to zero just as it should. So because there are several issues with the '86 wiring harness I was just going to swap the '84 into the '86. But now I'm not sure based on the different part numbers. Can anyone help with this?

Hate to say it but GM did crazy junctions in harnesses. This was in a harness that I pulled out of a Monte Carlo. Untouched. Factory that was in a taped harness that went to the fuse block. It had tape on it that was similar to duct tape but black not gray. Needless to say I was surprised to find this.

 

[fleming442]

Check the courtesy light fuse. They should have 12v backfed through the bulb, then the bulb (dome) lights when grounded.
mikester is right; that's probably a factory splice.
If the fuse is good and you still don't have power, there may be a power feed incorrectly positioned in the bulkhead connector due to the year change.
They're not that complicated; don't overthink it.

 

[justacruzr2]

Hate to say it but GM did crazy junctions in harnesses. This was in a harness that I pulled out of a Monte Carlo. Untouched. Factory that was in a taped harness that went to the fuse block. It had tape on it that was similar to duct tape but black not gray. Needless to say I was surprised to find this.

View attachment 177550

OK. That's exactly like mine. Just a few less wires. Seems like either a GM electrical engineer screwed up or the mfg of the loom screwed up. I guess in this case the best thing to do is take everything over from the '84 to the '86 when I do the engine swap. Thanks everyone for your replies. Oh...and the fuse was the first thing I checked.

 

[fleming442]

If you're not getting voltage on the white and the bulb isn't lit, check the bulb and for constant 12v on the orange.