Troubleshooting Trailer Turn Signal Lights Not Working with 2014 Peterbilt 579

Updated 12/26/2019 | Published 12/23/2019

Question:

I have a 2014 579 pet. The truck lights are fine but on the trailer all lights work but no turn signals on either side. Iv disconnected the pig tail from the truck and found that the pig tail actually isnt getting fire from the truck side witch is odd since ever light on the truck works any suggestions

asked by: Shaun

Expert Reply:

The 7-Way connector on your 2014 Peterbilt Semi will feature separate circuits for its brake and turn signal lights, while a standard trailer wiring setup will have these circuits combined. This is likely why the turn signals aren't behaving correctly and you aren't getting appropriate power at the connector.

All you should need to do to resolve this issue is add a converter like the Roadmaster # RM-732 before the 7-Way on the truck. This will combine the turn and brake light circuits so that they are compatible with the trailer's 7-Way connector and wiring. The truck's running lights wire will bypass the converter and go straight to the 7-Way just as it already is.

I have attached a short video review on this converter below that you can also check out.

expert reply by: Chris R