Help identifying wire plugs in '03 Chevy Express

aiguofer · 04-11-2020, 07:15 PM

Hey all, first post here!

I bought an AWD '03 Chevy Express last November and I just started stripping it for my build. It was originally a conversion van with lots of custom stuff running off its own wiring harness. I removed all the custom stuff and unplugged the harness, but as I was stripping I found 2 seemingly stock plugs that were unused. One in the front and one in the back. I was hoping you guys might be able to help me identify them?

The lights in the front were from the custom build and attached to their gnarly harness, so I pulled all that out. I'll be building a custom headliner for the front and want to include a dome light, and I have a hunch that the one unused plug in the front might enable me with that.

I had trouble uploading the pics, so I shared them in this Google Photos album: https://photos.app.goo.gl/wM147TNpr458i3oz8

The big plug is in the front driver side. The small one next to it that's plugged in goes to the map lights on the sun shades. Tried to get different angles to see the color wires going into it.

The other smaller one is in the back near the top tail light.

Any help would be greatly appreciated!!

TeleSteve · 04-13-2020, 12:06 PM

Take a look at the GM Body Builder Manual, it should show all the wiring diagrams.
https://www.gmupfitter.com/files/med...3_LD_GHVan.pdf

aiguofer · 04-13-2020, 01:57 PM

Oh wow, that's an incredible link!! thanks for sharing!

Unfortunately, it doesn't look like that's got the wiring diagrams... maybe they're available elsewhere on the site. Thanks!

carringb · 04-13-2020, 03:22 PM

Based on the description of locations, and not having a wiring chart for your van, I'd guess the large 8-pin on the B-pillar is for rear HVAC controls, and the small plug there is for dome lights. Same with the small plug by the rear door. If these are dome circuits, they should have an always-hot wire, since ground is switched for dome lights. The 4-pin connector might have 2 hots (brown?), with one constant ground (for map lights) and one switched ground (for courtesy lights).