Should Vehicle Tail Light Still Work If Power To The C67WR Converter Module Is Cut Off?

Updated 01/28/2026 | Published 01/06/2026

Question:

Hello- Trying to help a friend diagnose a problem with his Curt 56464 wiring harness. If the 12V battery power is cut off from the harness power converter, the vehicle lighting brakes, turn signals, etc. should still operate as normal, correct? In other words, if the 12V is cut off, only the trailer lights should go out. Thank you in advance for your answer. Dan C.

asked by: Dan C

Expert Reply:

Hello Dan, thanks for reaching out. Yes, you are right. If power is cut to the converter module, the vehicle lights should still function like normal. That signal is still being sent from the car to the rear lights. Without power to the converter there would be no trailer lights, but the vehicle lights should still work.

Are you having a problem with the Curt # C67WR harness? What is going on exactly? When we see problems with these its usually a bad ground, the module is not wired directly to the battery, or the plugs are not seated all the way. If you want to explain what is going on I am happy to look into it and see what can be done to help.

expert reply by: Jesse M

Jesse M.

1/27/2026

Hey Dan, what ended up happening with your friend’s Curt wiring harness after checking the power and ground connections? Sharing what you found could help others who run into the same issue.

Dan

1/27/2026

@JesseM Sorry for the delayed response. Solution turned out to be quite simple - a wonky fuse on the car side (not the converter). It was intermittent but once that was changed out, everything works as it should. Easy install, great product. Thank you again for the help.

Jesse M.

1/28/2026

@Dan Ah ok yes a bad fuse would definitely explain it! Glad you got it sorted out and it wasn't a problem with the converter itself. Thanks for sharing!