Driver Side Trailer Lights Not Working While Using 7 to 4-Way Adapter

Question:

I have 2011 Acura MDX I have the OEM 7 pin round harness, an adaptor to the 4 pin flat for the trailer. When everything is connected, everything is working except the drivers side tail light on the trailer : no lights are working at all for the tail light. Any idea what this could be? Thanks for your help,

asked by: Wayne

Expert Reply:

I would first remove the 7 to 4-way trailer connector adapter that you are using and test the driver turn/stop pin inside the 7-way with a circuit tester. If you get power here then plug the adapter back in and test the driver turn/stop pin inside this. If there is no power inside the driver turn/stop pin on the adapter then this has failed and will need to be replaced for which I recommend the 7- and 4-Pole Trailer Connector Socket w/ Mounting Bracket part # HM40975 as opposed to something like the Hopkins 7-Way RV to 4-Way Flat Trailer Connector Adapter part # HM47340 because they are much more reliable.

If you don't get power on the driver turn/stop pin inside the 7-way then you most likely just have a blown fuse or bad relay. However, if you get power inside the driver turn/stop pin inside on the adapter then you either have a short on the trailer or there is a bad ground on the light.

expert reply by: Conner L