Help. No Power to Trailer Running Lights, 2009 JKU

Hi folks. I have a 2009 JKU and a couple years ago installed a 7-pin trailer harness (bought from Chrysler). Since then it's worked fine but recently I found I am not getting power to the trailer running lights, or more specifically no power to the pin/blade on the vehicle plug that powers the trailer running lights. The brake/turn lights work fine. The PNP connectors appear solid, all fuses are good, and the vehicle tail lights operate.

I found two old threads on other forums with the same issue but there are no solutions posted and the OP's haven't replied to PM's to see how they resolved the issue. Anyone out there experienced this specific problem? And more importantly, found a solution?

I'll start tracing wires and looking for a short but since I found others have had the same issue in the past I thought this might be a malfunction I'm overlooking.

Thanks! Any help is much appreciated!


Is your ball clean? I have the 4 pin that plugs into the driver's tail light. The trailer needs a good ground, and I had my lights acting up due to a ground issue,due to I greased my ball. Wiped it clean and it fixed the problem. If he plug isn't hot, prob a broken wire along the route.


Ike, one of the wires on the towing-vehicle side of your four-wire setup should ground to the frame. If that connection is bad, the trailer may ground through the hitch (as you discovered by cleaning your ball), but you probably shouldn't rely on it; there's a good chance the connection will appear solid when you're stationary but when you're bouncing around on the road it's likely to be intermittent, causing the trailer's running lights to flash.

Sorry this isn't a help to Paul.


The OEM 7-blade trailer plug has it's own fuse for the trailer running lights. I ran into a similar problem on my 08JKU.

In installed the OEM harness myself (bought it from the dealer) so i knew where the fuse was. On mine it was near the battery connection.

Hope that helps.