Question on under-dash harnesses
 

I have an 87 Suburban 4wd, TBI 350, SM465 NP208. My under dash harness has some shorted/burned wires. I have a mechanical speedometer as well.
My question is can I use a 91 harness(squarebody) and just weed out the electronic speedometer or just leave it unplugged?
Thanks

Re: Question on under-dash harnesses
 

I'm fairly certain you'll need to repin the instrument cluster connector. A $10 universal de-pin toolset from Amazon, and it should be a cake-walk. The wire colors should be the same, but they'll be in different positions compared to the '87.

The neutral start wiring might be significantly different, if the donor is an automatic.

Otherwise, make sure the 91 harness is similarly equipped. Cruise, AC, etc.

Just curious -- did you convert the Burb to stick-shift? I kinda' assumed that none of them came with a manual.

Re: Question on under-dash harnesses
 

Thank You. No It is a factory manual trans. I have the original window sticker. 350 tbi, SM465/NP208

Re: Question on under-dash harnesses
 

Another thing. I'm reasonably certain that the R/V trucks kept the dash harness and the TBI harness separate, with only one or two plugs connecting the two.

The dash harness would have remained similar to the previous squarebody C/K trucks, with a few additions, such as the ALDL port and the check engine light.

If your problem is with one harness only, there's probably no reason to replace both.

Re: Question on under-dash harnesses
 

It's just the under dash and fuse block harness. I just got this Suburban yesterday, and the PO had a wire short and melt a fuse and some wiring...mainly the tan/white to the fuel pump module and running lights wiring. So I am going to replace the entire under dash harness.

Re: Question on under-dash harnesses
 

Note that the TBI harness is the big bundle of wires that exits near the passenger-side valve cover. It's all one harness, connecting everything on the engine, the TBI computer above the glovebox, and tying in with the dash harness as needed. There's no bulkhead connectors on that harness. I suggest you leave that harness alone, unless there's known problems in it.

Re: Question on under-dash harnesses
 

there is one plug going to the ECM from the bulkhead/fuseblock.

Re: Question on under-dash harnesses
 

could be. I figured that wire would go through a connector first, but I could be wrong.

What I meant by "bulkhead connectors", was the TBI harness doesn't split apart as it goes through the firewall, like the dash harness does. Sorry if I wasn't clear on that.