The Stovebolt Site Forums The Parking Lot Tons 'o Fun Replacement Wiring Harness for a 1948 Chevy 3800

Hi all,

I have searched the forums for wiring harnesses and read many posts and I am now more confused than when I started so please forgive me for asking about replacement wiring harnesses for my specific truck if it has already been covered somewhere else.

I have a 1948 Chevy 3800 flatbed dually that is all "original" (except the addition of larger rims sometime in the past and the current hacked up wiring harness).

I am keeping it all "original", meaning no updates as in NO 12v or turn signals or radios or A/C or alternator, etc.

I am seeking recommendations for the best replacement wiring harness option available for my purposes. It does not have to be the original cloth covered version (unless this is the best option) but specific for the 3800, well built, easy to install, good instructions, etc.

Thank you for your input!
josé

jose,

If will be using the original number/types of circuits, Jim Carter and Classic parts sell very nice plastic-coated wiring harnesses and good prices. They include extra wiring for turn signals, if you want to add them later.

Call them to see if the rear lamp cables are long enough for your 3800.

Classic Parts

Jim Carter

Chevs of the 40s probably has a similar harness.

Thank you Tim, I have added these two possibilities to my list. I will be selecting a harness in the next week.

Here's a 50-52 harness, ask if they offer the earlier harness.

https://brillman.com/wire-harnesses/?fwp_product_vehicle_compatibility=vehicles-chevrolet-truck

This shop is close to me.
They're making a somewhat modified one for my 51 GMC. They do really nice work and use the best materials as far as I can tell, I've visited a few times.

I got mine for my 1 Ton GMC from Jim Carter, worked great though I did have to add length for the rear lights.

Thanks to all of you for your input. I see that most (actually none so far..) ready to go setups do not include the longer wires for the 3800 taillights so I will have to lengthen.

There is a $50 difference between the kit offered by Jim Carter and the one by Classic Parts although they sound exactly alike. Not sure why..

I've sent a request to Brillman to see if they can make a 48 harness.

Brillman I'm sure can leave the tail light wires extra long for the 1 ton.

The main or apparent difference is the earlier AD trucks have a large fuse box on the firewall with 5 fuses.
The later AD trucks have a small box with only 2 fuses.

I believe the earlier harness include fuses for high beam, low beam, and park lights. The headlight switch also has a circuit breaker that (I believe) protects this wiring.
The later harness without these fuses still has circuit breaker in light switch.

Unless you're real concerned with exact originality I don't see as it makes much difference either way which version of the harness you use. So long as you have the appropriate fuse box to go with it.

Ask the replacement harness vendor about wire size. I bought my 3600 with a replacement harness already installed. It looked fine. However, the truck is still (will remain 6 volt) and I had low voltage to the headlights and heater blower motor causing dim lights and a slow, low air flow heater motor.

After searching for bad connections and grounds I resorted to using relays to fix the problems above. All's great now.

The replacement harness had 18ga wire going to the headlights which I believe is undersized for a 6v system, likely OK if 12v. I didn't check the wire size to the heater motor but it was Much smaller than the original it connected too at the motor.

Good Luck,
Ron

Hi Ron, I see that the classic chevy parts replacement wiring harness that Tim provided the link above for specifies either generator or alternator systems. I know it is not safe to assume anything but isn't the generator version going to be 6V and hopefully they are using the wire gauge specified for 6V? I will be trying to get a hold of someone there to verify but I have this feeling I won't really get a good answer..

Thanks!
josé

josé, well.....it could. Chevrolet trucks switched to 12 volt in 1955 (?) and 12v generators were common into the early 60's. So for approximately 5 or 6 years you had 12 volt generators. My guess is the difference the vendors honor has more to do with specific wiring harness connections (to a alternator or generator) than proper wire size based on system voltage.

Hopefully I'm mistaken.

Ron

I see on the post up above you are questioning the $50 difference between Jim Carter and Classic parts, Jim Carter does have provisions for turn signals (which worked out wonderful for mine). Not sure if others do since turn signals were not standard equipment in that era. Perhaps that's the cost difference, be sure to check if that's important to you.

Hi Ron, the only thing I can offer in regard to the classic chevy parts wiring harness is that it says 1947-1949 and is for a system with the generator. I will probably order this wiring harness and see if the wire gauges match what i have now and if they don't i will return it and get the custom one from brillman made.