1949 GMC 100 Wiring Harness

[Dave Mac]

Recently purchased the truck and had an electrical short on the old wiring. It's a long story. I bought a 6v harness online but the wire gauge definitely seems too small, so I'm returning it. Learned it was for Chevy, though they say it fits a GMC too. I would think 6v is 6v, but I'm a newbie to the 6v world, so perhaps there are differences.

Needless to say I need to update/replace my harness. I'm keeping it 6v original so need a harness that meets the specs. Any ideas/suggestions on where to get a proper one? Thanks in advance for any advice.

 

[Bill Hanlon]

Don't know where you got yours, but Chevs of the 40s advertises a GMC specific harness for 1947-49 as their part number 4188864G at $934.75 "special order". They advertise the same part number without the trailing "G" for 47-49 Chevy trucks that is not marked "special order @ $897. They both have cloth covering. I've had good luck with other parts from Chevs of the 40s, but I've never bought a harness from them.

If it were me, I'd just wire it myself using modern wire. But I was in the electrical/electronics business from B-52 aircraft in the late 60s, through mainframe and minicomputers in the 70s and 80s, into microcomputers (including a couple of home builts) mid 80s and finishing with design debugging at Compaq and HP in the 90s until 2013.

I can probably dig up a wiring diagram for a '49 (or there about) GMC truck if you are interested. I have one for a '51 model and I doubt there is any difference.

 

[Dave Mac]

Fabulous! I'm checking them out now. Appreciate the response. Happy motoring!

 

[Chiro]

Man!!! That's a spendy harness. I bought the inexpensive harness for my 55.1 Chevy years ago. IIRC it was well under $200. It worked so well that I used the same harness to wire up my Model A hot rod with modifications. Even used the Chevy truck headlight switch and ignition switch. Looks period correct and has been trouble free for years and years. I converted mine to 12V.
Andy

 

[Bill Hanlon]

I agree about the $$$ Andy, but Dave is talking about "keeping it original". A universal harness can be had for 1/4 the price, but would have a lot of unused circuitry and require some knowledge and confidence to install. Also, most "universal" kits would need to be modified to support the stock ammeter and generator/voltage regulator.

I've uploaded a '51 GMC wiring diagram. It uses 2 fuses like my '52. I have a '49 Chevy diagram that uses 5 fuses, but the diagram appears to have been drawn by an unknown individual, so I don't want to throw it into the mix. Just note that Dave's '49 truck may also have 5 fuses.

 

[Bill Hanlon]

Attached is the wiring diagram from a '49 GMC Owner's Manual.