OEM trailer wiring Suburban R20

[496bb]

Ok guys, I see the harness coming out of the firewall on engine side- runs along the frame rail driver side, has the typical yllw/dk grn/lt grn/brn wires, and the two wires for the fuel pump.

After pulling all the tape off and studying all these splices, I just can’t imagine this is the way GM did it. Truck does have all the trailering RPO’s. I’m 3 rd owner, I know 2nd owner didn’t modify this. It had one of the old round 6 pin connectors and an old hydraulic brake controller.

While the fuel tank is out, gonna install a new hitch and try to make this wiring better, along with a modern trailer brake controller.

Anybody know if your factory trailer wiring was done this way. I can see how they’ve spliced off the main 4 wire line to send appropriate signal to left and right, and trailer hookup, and all the plastic connectors look the same and original. Even the tag light wire is spliced into the brn wire. Just thought the main 4 wire line should’ve entered a connector and the y off from there.

 

[89Suburban]

Ok guys, I see the harness coming out of the firewall on engine side- runs along the frame rail driver side, has the typical yllw/dk grn/lt grn/brn wires, and the two wires for the fuel pump.

After pulling all the tape off and studying all these splices, I just can’t imagine this is the way GM did it. Truck does have all the trailering RPO’s. I’m 3 rd owner, I know 2nd owner didn’t modify this. It had one of the old round 6 pin connectors and an old hydraulic brake controller.

While the fuel tank is out, gonna install a new hitch and try to make this wiring better, along with a modern trailer brake controller.

Anybody know if your factory trailer wiring was done this way. I can see how they’ve spliced off the main 4 wire line to send appropriate signal to left and right, and trailer hookup, and all the plastic connectors look the same and original. Even the tag light wire is spliced into the brn wire. Just thought the main 4 wire line should’ve entered a connector and the y off from there.

I can't believe how clean and rust free that Burby is underneath that is disgusting haha

 

[YakkoWarner]

Thats actually shockingly better than what I found on my 1989. If memory is to be trusted, my 4 way trailer connection did break out from the tail lights through a factory connector, but from there it all went downhill.

In the approx. 2 feet of wiring between the split off and the 4 way at the bumper I had no fewer than 5 wire nuts, 3 gullitoine-style connectors and 2 or 3 twist-and-tape atrocities. And someone "customized" the 4 way so the ground was actually wired to the reversing lamps. Surpisingly enough it actually worked when I hooked up a trailer for the first time (apparently my trailer has a decent ground through the ball) not knowing what lurked behind the 4 way....right up until the first time I selected reverse to place the trailer where I needed it at the destination.

Needless to say every bit of that abomination went away when I got home from that adventure, and its actually wired functionally, safely and sane now. I will try to get under there with a camera sometime soon and confirm that there was a factory split-off connector, and if there is see if I can grab a pic thereof.

 

[bucket]

Ok guys, I see the harness coming out of the firewall on engine side- runs along the frame rail driver side, has the typical yllw/dk grn/lt grn/brn wires, and the two wires for the fuel pump.

After pulling all the tape off and studying all these splices, I just can’t imagine this is the way GM did it. Truck does have all the trailering RPO’s. I’m 3 rd owner, I know 2nd owner didn’t modify this. It had one of the old round 6 pin connectors and an old hydraulic brake controller.

While the fuel tank is out, gonna install a new hitch and try to make this wiring better, along with a modern trailer brake controller.

Anybody know if your factory trailer wiring was done this way. I can see how they’ve spliced off the main 4 wire line to send appropriate signal to left and right, and trailer hookup, and all the plastic connectors look the same and original. Even the tag light wire is spliced into the brn wire. Just thought the main 4 wire line should’ve entered a connector and the y off from there.

Those splices are typical for GM products, as well as other manufacturers too. Other than the potential for corrosion, they are a reliable connection.

My '88 has the original trailer harness, but I've never inspected how the harness is spliced in. But it also has an AUX wire and Brake wire that ran up to the engine compartment and were not hooked up.