Since your 2007 Lexus GX 470 has the factory 7-way connector then it does indeed seem that there is a blown/missing fuse causing the issue.
Fuse 8 in the engine bay fuse box is the fuse for the lights, so I recommend making sure that the fuse is not blown or missing.
If the fuse checks out, then use a circuit tester like # PTW2993 to test the 3 o'clock pin on your 7-way connector and see if there is power on the pin. While you are there go ahead and check that there is no corrosion or... view full answer...
Since the lights work intermittently I do not think that your 2008 Lexus GX 470 suffers from the same issues that would require adapter # C57003. I think what we are seeing here is a ground problem or general wiring issue.
Ground problems normally show up when there is more draw on a system such as when you have the running lights on and then use another function like a turn signal or brake light but can show up any time.
Make sure that the vehicle side and trailer side connectors are... view full answer...
The Hopkins Plug-In Simple Vehicle Wiring Harness # HM43374 is the correct wiring if your 2003 Lexus GX 470 came with the factory 7-Way and should be used as a replacement. If your vehicle didn't come with the factory 7-Way then the only way that I know how to help you is to offer theModulite Vehicle Wiring Harness Kit # C59236 which comes with just the 4-Way but does require splicing for the installation.
If your GX 470 did come with the factory 7-Way the only other thing I would know... view full answer...