Identifying Wiring on 1997 GMC Safari

Updated 10/08/2018 | Published 10/05/2018

Question:

I am preparing to install trailering equipment on a recently-acquired GMC Model M11006 compact van and need some ID help on the stock harness stub in the jack compartment, on which I plan to use one Erich Jäger or two Hopkins powered converter/isolators to protect the truck from possible shorts on the trailer side. Ive only some of the stock wires IDd: 9 - 0.8 Brown / Tail and Marker 18 - 1.0 Yellow / LH brake and turn 19 - 1.0 Dark Green / RH brake and turn 24 - 1.0 Light Green / reverse 1647 - 2.0 Dark Blue / electric-brake drive prepared for and 1742 - 2.0 Orange / hot at all timesinch +Vcc from engine compartment UPFIT BAT fuse to trailer and/or isolator prepared for, plug-in for Convenience Center attached. I also have two White wires, one 1.0mm and one 2.0 mm. What possible functions might the stock White wires have? 20 - 1.0 Light Blue / center brake lamp feed not IDd in the stock stub.

asked by: Bret S

Expert Reply:

You have already identified six of the functions on your 7-way, 1) Tail/Running Lights 2) Left Turn/Stop 3) Right Turn/Stop 4) Reverse 5) Brake Controller Output 6) 12V power.

The only wires not identified were the ground wire - which make sense if you were testing it with a circuit tester because it would not have an identifiable function - and the other is likely the third brake light wire.

If you take a look at the diagram I added you can see the standard pin functions of a vehicle-side 7-way.

I have added a link to a help article on wiring which I also strongly recommend checking out.

expert reply by: Kyle S