How to Test Old Trailer Wiring to Find Out What Each Wire/Circuit Does
Updated 06/11/2018 | Published 06/07/2018
Question:
I have a white, red, green, pink and black wire on my trailer.....I just need to figure out which one controls what and cannot find anything. Green is supposed to be right Red may be left White ground? But no idea what black and pink are for...
asked by: Rachael L
Expert Reply:
You have discovered the "dirty little secret" of trailer wiring: wire colors are not a consistent and reliable way to figure out what each one does! But it is easy enough to check this simply by applying 12V power to each circuit and noting what function on the trailer comes on.
It is easiest to use your vehicle battery (or a well-charged spare battery) along with a set of jumper cables and two lengths of wire. This makes it simple to apply +12V power to each circuit on the trailer (one at a time, of course) to see what function activates. Then you can label them and complete your wiring.
Usually (but not always) a trailer ground is the white wire, so I would start off your testing with this, but of course you can trace the wire that actually connects to the trailer frame. The ground usually has a ring terminal on it. Once you know which wire is ground you can connect that to battery negative and then one by one apply the +12V wire to the leads on the trailer to see what lights up.
You can also refer to the article on wiring that I included for you; this shows the usual wiring formats for RVs, both on the vehicle side and the trailer side.
Product Page this Question was Asked From
Pollak 6-Pole, Round Pin, Trailer Wiring Connector - Trailer End
- Trailer Wiring
- Trailer Connectors
- Trailer End Connector
- 6 Round
- Plug Only
- Pollak
more information >
Featured Help Information
Miscellaneous Media
Continue Researching
- Shop: Suspension Enhancement
- Shop: SumoSprings Solo Custom Helper Springs - Rear Axle
- Shop: Trailer Hitch
- Search Results: rv door locks accessories and parts
- Search Results: hook and keeper trailer door holders
- Article: Trailer Wiring Diagrams
- Video: Buyers Products Hook and Keeper for Enclosed Trailer Door Review
- Video: Comprehensive Review: T-Style Hook and Keeper Door Holder for RV or Enclosed Trailer
- Shop: Trailer Wiring
- Shop: Draw-Tite Max-Frame Trailer Hitch Receiver - Custom Fit - Class IV - 2"
- Search Results: rv door locks
- Video: Checking Out the Electric Jack w/ Footplate
- Search Results: locking latches rv door locks
- Video: Trailer Hitch Installation - 2004 Lexus GX 470
- Search Results: power tongue jack
- Search Results: heat shrink butt connector
- Search Results: progressive dynamics
- Shop: Electric Jack w/ Footplate - A-Frame - 25-1/8" Lift - 3.5K - Black
- Shop: Locking L-Shaped Handle - 4" Long - Chrome
- Shop: Curt Trailer Hitch Receiver - Custom Fit - Class III - 2"
- Article: Wiring Trailer Lights with a 7-Way Plug (It's Easier Than You Think)
- Q&A: Replacement Door Handle For A Casita 2002 16ft. Travel Trailer
- Shop: Redline Locking "L" Style Door Handle - 2-1/2"
- Video: Feature Review Hopkins Tow Doctor Vehicle End Test Unit
- Video: What to Know About the Hopkins Tow Doctor Vehicle End Test Unit
- Video: Checking Out the Hopkins Tow Doctor Trailer End Test Unit
- Shop: Buyers Products Hook and Keeper for Enclosed Trailer Door - Zinc Plated
- Article: How to Measure for Trailer Hitch Drop
- Article: My Trailer Hitch Doesn't Fit
- Article: Troubleshooting 4 and 5-Way Wiring Installations
on Trailer Wiring
