Can't figure where this plug goes behind dash

TheStug · August 7, 2020

I'm putting my truck back together (new cab), and I've got almost everything except for this one plug and for the life of me I cannot figure out where it goes.

Attaching pictures. It's not the light sensor which I show in the first picture, already plugged.... I'm stumped right now. Not sure if it is plugged up top or down low (I think I've eliminated the steering column because I don't see any extra receptacles). Already have 2 plugs ready to go for A Pillar tweeters so that's not it either. I've looked under the dash and at the top part of the dash multiple times and can't find anything. I'm really trying to avoid having to pull out the dash a second time

Color of wires. I'm off to look for wiring diagrams but I usually don't have much luck finding what I'm looking for.

A - Yellow/Blk stripe

B - Brown/White Stripe

C - Green/Blk stripe

D - Green/White Stripe

E -

F - Solid Tan or light brown

G - Solid Dark Green

H -

TheStug · August 8, 2020

Anyone able to provide document resources? Exploded views etc? Forward view Pictures of the plugs themselves (to see the tab shape would help quickly identify it) with pin out #s and what the function of the plug is would also be excellent. I can't seem to find anything useful. the GM upfitter had pictures of some plugs, but nothing related to this.

I am also dealing with trying to replace the back half of the parking brake cables (both), but so far cannot even find parts diagrams. So basically, my big challenge right now is finding some freaking diagrams. I don't remember it being so hard to find diagrams. I really have only owned 90s stuff to this point.

davester · August 8, 2020

the full service manual has pinouts, wiring harness path (at least the FSM for my truck has that). You might try subscribing to it at a site like alldatadiy.com

carkhz316 · August 9, 2020

I tried looking at Alldata for you, but I can't discern where it goes either. My best guess according to the diagrams is one of the blend door actuators as they share some of the colors, but most of those are 5 wires (not sure on the actual pin count though). In lieu of that, run the truck and see what doesn't work anymore.

TheStug · August 10, 2020

I pulled out the dash slightly (i didn't disconnect any cables so i could only go out so far) but I could not see anything. I did find one extra unused plug neatly tucked near the upper hvac tube delivering air to the very left side of the dash but it's not the correct shape for the receptacle. I'm thinking GM just made a standard wiring harness and whatever option I didn't get on the truck, the plug is left dangling.

I am leaning toward it being a HVAC thing or an additional steering wheel control feature. Anyone with heavily optioned trucks, if you wouldn't mind looking under in the area of the steering column and see if you can find this plug? I'll see if i can find a ltz or something to look at. Peace of mind and all that. I'm gonna go ahead and proceed with putting things together and turn it on as soon as i can.

Fingers crossed

carkhz316 · August 10, 2020

5 hours ago, TheStug said:

I pulled out the dash slightly (i didn't disconnect any cables so i could only go out so far) but I could not see anything. I did find one extra unused plug neatly tucked near the upper hvac tube delivering air to the very left side of the dash but it's not the correct shape for the receptacle. I'm thinking GM just made a standard wiring harness and whatever option I didn't get on the truck, the plug is left dangling.

I am leaning toward it being a HVAC thing or an additional steering wheel control feature. Anyone with heavily optioned trucks, if you wouldn't mind looking under in the area of the steering column and see if you can find this plug? I'll see if i can find a ltz or something to look at. Peace of mind and all that. I'm gonna go ahead and proceed with putting things together and turn it on as soon as i can.

Fingers crossed

I took that into consideration as my truck is a LTZ, and I checked all the options I could think of and there really isn't any more that are in the dash that I have that differ from the base model. When you look at the plug, are there any "witness marks" on it (scratches/ striations from being plugged/ unplugged)? From what I can see, it looks like a lot of it is dusty, insinuating that it's a leftover for another model/ option and was never plugged in. Here's hoping you can get it solved. Good luck!

Edited August 10, 2020 by carkhz316