trailer wiring harness pin out

D

dace voit

New member
I'm sure this has been covered before but I can't find it.

I'm looking for the factory tow harness pin out. The truck we got came with a 7-pin connector that we have never used in the 10 years of owning the truck. I tried it out the other day and it was old and weathered and wouldn't work with the trailer we were towing. I am trying to replace with a new connector, but need to know the pin out to make sure the harness is still good.
 
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dace voit said:
I'm sure this has been covered before but I can't find it.

I'm looking for the factory tow harness pin out. The truck we got came with a 7-pin connector that we have never used in the 10 years of owning the truck. I tried it out the other day and it was old and weathered and wouldn't work with the trailer we were towing. I am trying to replace with a new connector, but need to know the pin out to make sure the harness is still good.
Click to expand...

What year is your rig? Maybe i could help
 
Pedrojr80 said:
What year is your rig? Maybe i could help
Click to expand...

2001 Limited with factory tow package.

Magmotor said:
Don't know about the 7 pin but this is the EWD for a 2002 Trailer Tow and the Connectors T9 & T10 pin out....hope this helps....
Click to expand...

That does help a bit. I've seen the first file but hadn't seen the connector info. The latter did help a bit and I could relate it to the wiring diagram in file #1. However, I couldn't make sense of what the wires were in the diagram relative to what's on my truck.

I'm going to look at it again tomorrow as I might've had my wiring wrong when testing. I thought there was a black wire in the mix which I took to be ground, but in hindsight that wire was likely a weathered brown wire, which is the standard color for tail lights. White is ground in trailer wiring. Duh.

:facepalm:
 
dace voit said:
I'm going to look at it again tomorrow as I might've had my wiring wrong when testing. I thought there was a black wire in the mix which I took to be ground, but in hindsight that wire was likely a weathered brown wire, which is the standard color for tail lights. White is ground in trailer wiring. Duh.
Click to expand...

I'm assuming you checked the 25a Towing Fuse and its good. Perhaps someone changed up the wiring to match with their trailer...:shrug: white & black are ground on this schematic.....luck..
 
One thing to check if none of that works is the little tailight converter box thats under the carpet in the cargo area and in the back left quarter panel near the tailight (behind the trim).

These expensive little boxes are bound to go out at some point and can be remedied with a cheaper kit from Hopkins. Let me know if it doesn't work and I'll try to find the part number for you.
 
So I did have the wiring incorrect in my previous

testing. There is power to the wires, however there is 12v to the left turn signal, but 24v to the right and tail lights. This seems weird. Is this a normal thing or a sign of the converter in the rear quarter panel going out?
 
The voltage does fluctuate when you depress brakes, turn running light on and off, or use a turn signal, but it shouldn't be that much. And especially when you haven't done of those things (i.e. the truck is just sitting there running).

I was not aware that 3rd gens came with a 7-way plug, so it could be an aftermarket job that someone did. If that's the case, it would be worth looking for the converter box and making sure that whatever adapters they used were hooked up correctly with the pin-outs, maybe even testing the voltage at the plugs.

Did it come with a brake controller installed?
 
The 7pin is wired into the factory 4pin harness.

I don't know any more about the controller or if there is one in there. I just read in a previous post about them going bad. I assume it would be a converter for multiple wires for tail lights/turn signals?
 
dace voit said:
I don't know any more about the controller or if there is one in there. I just read in a previous post about them going bad. I assume it would be a converter for multiple wires for tail lights/turn signals?
Click to expand...
Try the meter with the engine running, lights on, blinker blinking and emergency brake on and see it that changes the voltage. If it doesn't i'd say the converter is suspect....I took a look at my harness connector and it ain't anything like the connector pdf T10 ...it looks more like the T2 or T8...4 horizontal pins...1 male and 3 female....so I don't know whats up with that...sorry for the confusion...
 
I haven't had the time to get back into this

lately. I'll test the voltage with the engine running next.

The wiring is just a 4 pin wire set coming from the factory connector under the left quarter panel that's wired into a 7 pin connector to accomodate the cable coming from the trailer. Essentially a 4pin set up with a different receptacle.
 
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