Can Wire Colors Be Trusted on 7-Way Trailer Connector Tester
Updated 01/12/2026 | Published 09/04/2024
Question:
Hello, I have a 7 pin trailer connector tester and I’m unsure if it’s wired correctly. It is labeled where the wires go as far as colors but some of the colors aren’t matched on the tester?? Is every wire supposed to go where the color is labeled?
asked by: Hollie
Expert Reply:
Hi Hollie; in general you cannot trust wire colors on trailers. There are some universal colors for different functions but there are too many instances where the colors don't match. Trailer manufacturers have a bad habit of using whatever is on hand so if they ran out of green wire that day (or some other color) they will proceed with whatever else is handy.
It is for this reason that you always want to match wires by function instead of color. For example, the Hopkins 7-Way RV Style Trailer Connector # HM48503 you were looking at uses the following:
Green: right turn signal (RT)
Yellow: left turn signal (LT)
White: ground
Brown: tail light and side marker lights (TM)
Blue: electric brake (EB)
Red: auxiliary (AX)
Purple: backup/reverse lights (BU)
If this is what you have you know what color matches what function on the connector side. You need to match up the corresponding wires by function from the trailer. If you aren't sure, you can always trace them back to find out which function the wire is tied to.
Featured Help Information
Miscellaneous Media
Continue Researching
- Search Results: as2t216
- Shop: Replacement Lens for RVSTL61 and RVST61 Tail light
- Q&A: How To Troubleshoot A Non-Functioning 7-Way Extension
- Q&A: Troubleshooting Hopkins 7-way Connector # HM48503 Having All Test Lights On But No Trailer Lights
- Q&A: Three Flashing Lights on Hopkins 7-Way RV Style Trailer Connector HM48503
- Q&A: Connection Indicators on Hopkins # HM48503 7-Way Connector
Robin H.
1/12/2026
Hey Hollie, how did things go with matching the trailer wires by function instead of color on your 7-way connector? Knowing what worked for you could really help others sorting out mismatched wiring colors.