We rented a Uhaul trailer to move a large appliance we bought. It's our first hauling experience with our new-to-us 2008 GX470, which towed perfectly, and we're so very pleased with it. However, the running lights on the trailer did not work. The Uhaul guy changed the wiring harness on the trailer with the same result: no trailer running lights. Hazard lights work and the turn signals work. Thankfully, we hauled in the daytime. Upon getting home after returning the trailer, I spent a bit of time here on CL trying to find what's up, as well as test out the plug with my multimeter. I have power on the turn signal/brake light pins and the battery pin, but the trailer lights pin has no power (on the 7 pin harness plug). Searching around CL netted me the following:
1. 2003 versions had a fuse behind the rear driver's tail light that might go out. Ours is a 2008, so this fuse doesn't exist in ours (at least that I know of)
2. The fuse box in the engine department has two relays (small fuse box near main fuse box). I swapped the relays, but there was no change in results upon retesting.
3. Fuse box at the driver's knee contains a trailer lights fuse which is not blown.

Is there anything I'm missing? Is there an in-line fuse? I have an appointment with our mechanic to diagnose and repair it on Monday; however, if the issue is a simple fuse, then I'd prefer to swap it myself versus pay an $85 diagnosis fee and then $10 for a fuse. Thanks in advance for any insight.

Thank you!
Micah

 

Not to ask the obvious but were your headlights switched to the on or parking light position? If not the trailer running lights won't come on.

 

It's a great question. They were switched on while we were at Uhaul and then while I tested them in the garage. The headlights are normally on "auto" and to your point, would not activate the tail lights during the day time.

 

Update: What I didn't realize is there is a 40 amp fuse in the fuse box in the engine compartment. That fuse was blown. Off to the parts store for a replacement!