Rear wiring harness
 

I decided to undo the years of hob job wiring in the rear end and put in a nice weather resistant junction box. Well I cut the whole harness just in front of a small chasis support as it was the closest place I could get all original wiring. There's a total of I believe 8 wires. I have 5 identified, and if memory serves me correctly, last time I was wiring this truck it had a wire dead ended from factory so that puts me at two mystery wires. Anyone have the wire functions and respective colors for these 8 wires? I've got both turn signals, reverse, ground, and marker. 1 wire is a factory option and the next two ??? Thanks for any help.

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Rear wiring harness
 

I looked at my chiltons manual this morning but that didn't do much good. I think I'm going to get some WD-40 on a rag and wire down the wires, get them nice and clean and do some color hunting. Just a shot in the dark here but I'm wodering if one of those wires is my ground for the low fuel light that doesn't work.

Rear wiring harness
 

Wipe down the wires***

Rear wiring harness
 

So these are the colors of the 8 wires...
Black/yellow
Grey
Violet/black
Grey
Brown/green
Violet/black
Grey
Green/brown

Gonna spend some time with the wiring diagrams.


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Rear wiring harness
 

And I can see some of the colors are wrong already... Sweet...


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just pulled a wiring harrness out of a parts truck it is a 93 w250 i will go check it and see what they are you dont have abs on rear of your 89 or do you, someone may have changed it at some point.

Trailer brakes ? :c:

purple- black should be brake lights +++ green with brown stripe is right turn===brown with green is left turn---black with yellow stripe is ground=== i dont have a grey but would guess they are feeds for marker lights might try this . my help . may not

Rear wiring harness
 

Has rear abs, wiring for abs is before the cut. It has two reverse wires bc of a splice made further up for left an right reverse lights. I think it has two grounds... I might have it figured out. I'll double check the wire color tomorrow.


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ok thought i would try to help out a little on some of the colors

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have fun with the wiring .

One of the wires to the rear is actually the ground for the tank sender. The ground splices on the rear somewhere and then goes forward to the tank. I cut my harness off after the abs split and I lost the fuel gauge. Tracked down the wire and its all good. Kinda scratched my head on that one.

Rear wiring harness
 

See richie, I thought the same exact thing for the tank ground. I did the same thing on my 84. Thank you for the help terra, some of the wires you're right on. The purple/black are reverse, and the black/yellow is marker lights. Your turn signals are the same as your brake lights. I'm thinking i'm just gonna hook all the grey wires together and that'll take
Care of everything, I am however going to get accurate wire colors and do a quick write up for others future reference on here.


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Rear wiring harness
 

http://tapatalk.com/mu/4ad422ab-3888-e4e6.jpg well this is the finished product,
Wire quantity is posted last
Black/yellow- marker lights (1)
Purple/black- reverse lights (2)
Grey- ground (3)
DarkGreen/brown- left turn (1)
Brown/light green- right turn (1)
Both turn signal wires are energized for stop.
Total of 5 purposeful wires
Total of 8 wires in the factory harness if it were to be cut right behind the Rear ABS unit. Hope this makes it to a sticky, or atleast helps someone out.


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forgot about reverse lights

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forgot about reverse lights
that box is the wat to do it that will keep out the elements

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will save me a sometime when i get my son truck back together will be putting on a flatbed .

Looks great and thanks for the help. I used this when I was looking into wiring in a new hitch. After looking at it, I too want to get rid of the hodge podge from previous owner and get it all done right. What specific junction box did you use? Id like to wire mine up similarly.

Thanks again!