79 rear wiring harness oddity (1 Viewer)

[MOTOV8R]

So I pulled the rear wiring harness to clean it up and found an extra plug. It’s in the middle of the rear frame cross member, midway between the tail light pig tails. It is the same style plug as the rear side marker lights and the harness appears factory (in the pics I have started to pull the factory wrap). It has a green wire and a black wire. Tested the wires and the green wire has continuity with the green wire on the marker light. The black wire has continuity with ground (white/black). It’s not license plate lights, those come off the harness at the passenger side rear marker light and have bullet connectors. I checked the schematic and didn’t see anything. Any guesses?

 

[B y r o n]

Since it is in the middle, is it possible they are for trailer lights?

 

[MOTOV8R]

Since it is in the middle, is it possible they are for trailer lights?

Hmm, maybe. I did just find this thread where the plug is mentioned.

Decent FJ40 trailer wire connect method

I would like to put a 4-flat trailer connector on my 1980 FJ40. Someone did the past with tap-a-lines in the usual hackneyed way and I have repaired the harness. Has anyone ever found a decent/robust way to connect trailer wiring on an FJ40? thanks - Steve

forum.ih8mud.com

 

[Living in the Past]

Pretty sure my 79 has the trailer plug. I know my 10/75 has one.

Looking thru old photos appears I cleaned up a PO wiring hacks back in 2019.

While not being used it did have this there not being used.

This a a 3/79 FJ40.

 

[45Dougal]

Number plate light for pickups?
Probably common harness across all models.

 

[wimberosa]

Wild.. Did not have that plug on my May '79 harness. I had to add it when I rebuilt my harness from scratch.

 

[MOTOV8R]

Pretty sure my 79 has the trailer plug. I know my 10/75 has one.

Looking thru old photos appears I cleaned up a PO wiring hacks back in 2019.
View attachment 3482567
While not being used it did have this there not being used.
View attachment 3482569View attachment 3482570
This a a 3/79 FJ40.

View attachment 3482568

I think in the other thread you said it was on a schematic, what is it called on the schematic?

 

[Living in the Past]

I think in the other thread you said it was on a schematic, what is it called on the schematic?

Didn't for get about this just been too busy to do some research. My post in the other thread was about wiring diagrams not schematics. Those are two completely different. Diagrams show wire routing while schematics how things work. I am not showing any trailer sockets or trailer socket changeover switch in any schematic for the 75-82 for US and Canada FJ40s. At least in the Haynes manual. But they do show a 75+ for non US and Canada 40 series. That one schematic shows how an optional trailer socket and trailer socket changeover switch. The switch only turns off the turn signals to the back of the 40 and over to the trailers. This is to keep for overloading the flasher.

Unfortunately not around my 10/75 which a 76 model. It has the trailer that I assume would plug into the trailer socket and switch. The other markets schematic have the code for all the wire colors. This 76 is a prototype with a Borg/Warner full time 4WD transfer case. Has all the US emissions but possibly a non US market tail light harness was used. Today instead of a switch just using LEDs in the trailer. should solve load on the problem.

 

[MOTOV8R]

Didn't for get about this just been too busy to do some research. My post in the other thread was about wiring diagrams not schematics. Those are two completely different. Diagrams show wire routing while schematics how things work. I am not showing any trailer sockets or trailer socket changeover switch in any schematic for the 75-82 for US and Canada FJ40s. At least in the Haynes manual. But they do show a 75+ for non US and Canada 40 series. That one schematic shows how an optional trailer socket and trailer socket changeover switch. The switch only turns off the turn signals to the back of the 40 and over to the trailers. This is to keep for overloading the flasher.

Unfortunately not around my 10/75 which a 76 model. It has the trailer that I assume would plug into the trailer socket and switch. The other markets schematic have the code for all the wire colors. This 76 is a prototype with a Borg/Warner full time 4WD transfer case. Has all the US emissions but possibly a non US market tail light harness was used. Today instead of a switch just using LEDs in the trailer. should solve load on the problem.

Thanks for checking on it. Did the diagram label it? I suppose it could be used for a trailer, it would provide parking lights which would illuminate it, just not indicate braking or turning. It would work as an absolute minimum I suppose. I may use it as the lights for my license plate since I converted my 79 to a tailgate.

 

[Living in the Past]

Wiring diagrams ended with the 74 model and switched to schematics in 75. Trailer socket and trailer socket change over switch are the terms used for both is diagrams and schematics.

The three wires in the plug are not a socket. My 79 is at another location. Wouldn't take long to identify those three wires in the plug.