How to Wire 7-Way Trailer Connector on 2008 GMC Sierra 3500
Question:
I read a wiring description, but I have different wire colors from what was shown. The colors I have are: White, 12 ga. Red, 14 ga. Yellow, 16 ga. Drk blue, 16 ga. Purple, 16 ga. Drk green, 16 ga. Lt green 14 ga. HELP...
asked by: Steve
Helpful Expert Reply:
Wire colors alone are not a reliable method for connecting vehicle or trailer wiring since they are not always consistently used. There are common wire colors for certain functions, such as a brown wire for trailer running lights, but there is no guarantee that this is the wire color used on all trailers or vehicles.
But since you provided the wire gauges too, that does help narrow things down. A heavier-gauge white wire will typically be ground; the other larger-gauge wires will typically be for +12V auxiliary trailer power (likely to be the red wire) and trailer brake power (light green wire).
The best way to go about wiring a 7-way like # PK12-707E is to use a tester like # PTW2992 to confirm the function on each wire. Have a helper activate each light function and apply the tester to each wire while the function is on. This will tell you which wire does what. Then all you need to do is refer to the linked article on wiring to see the function assignments for each of the contacts on a 7-way.
Make sure your main ground connections are secure and made to a clean bare metal surface. Weak grounds can cause all sorts of lighting problems so make sure these are solid. You can apply dielectric grease like # 11755 to help protect those connections from corrosion.
Products Referenced in This Question
Dielectric Grease for Electrical Connectors, 2 oz.
- Accessories and Parts
- Trailer Wiring
- Wiring
- Dielectric Grease
- LubriMatic
more information >
Product Page this Question was Asked From
Pollak Black Plastic, 7-Pole, RV Blade-Style Trailer Socket - Vehicle End
- Trailer Wiring
- Trailer Connectors
- Vehicle End Connector
- Plug Only
- 7 Round - Blade
- Pollak
more information >
Featured Help Information
Miscellaneous Media
Continue Researching
- Article: Wiring Trailer Lights with a 7-Way Plug (It's Easier Than You Think)
- Shop: Roadmaster Single Park Light Diode
- Shop: Trailer Wiring
- Article: Which Hitches are Made in the USA
- Video: Best 2008 GMC Sierra Hitch Options
- Shop: Trailer Hitch
- Video: Review of Roadmaster Tow Bar Wiring - Single Park Light Diode - RM-690
- Shop: Pollak Black Plastic, 7-Pole, RV Blade-Style Trailer Socket - Vehicle End
- Shop: Progressive Dynamics 4100 Series RV Converter w/ Charge Wizard and AC/DC Distribution Panel - 35 Amp
- Shop: Curt Trailer Hitch Receiver - Custom Fit - Class III - 2"
- Shop: Curt Trailer Hitch Receiver - Custom Fit - Class IV - 2"
- Shop: etrailer Trailer Hitch Receiver - Custom Fit - Matte Black Finish - Class III - 2"
- Search Results: in bed trailer plug
- Q&A: What is the Voltage and Amperage Rating for Roadmaster Parking Light Diode
- Q&A: Will Roadmaster Single Park Light Diode Get Hot To The Touch
- Q&A: Is Diode Needed to Prevent Trailer Battery from Backfeeding to Breakaway System
- Shop: 7- and 4-Pole Trailer Connector Socket w/ Mounting Bracket - Vehicle End
- Video: Roadmaster Single Park Light Diode Installation - 2012 Jeep Grand Cherokee
- Q&A: Recommended Diode for Charging Line From Motorhome to Towed Vehicle (Toad)
- Search Results: heavy duty receiver hitch
- Article: Trailer Wiring Diagrams
- Video: Choosing the Right Trailer Wiring
- Q&A: Trailer Running Lights Do Not Work but Brake Lights and Turn Signals Do Work
- Q&A: Troubleshooting No 12 Volt Power at 7-Way Trailer Connector on a 2009 Chevy or GM Duramax Pickup
- Q&A: Fuse Locations for Trailer Lights on 2008 GMC Sierra
- Article: Brake Controller 7- and 4-Way Installation Kit (ETBC7)
- Search Results: trailer hitch
- Article: How to Choose the Right Trailer Hitch Class
- Search Results: hitch
- Video: Choosing the Right Brake Controller
on Trailer Wiring
