An aftermarket trailer adapter module was installed in my WRX when it was new. The technician tapped into the wires in the harness in the right side of the cargo area. (I cannot find the connector supposedly there for this.) It apparently has never worked correctly. I discovered on a trip I had no tail lights and the turn and brake were acting strangely. Upon investigating, I discovered that the brake and battery leads had been reversed. During diagnosis, I discovered there is no power on the lead that provides power (battery) to the module. Tapping into the cargo light lead makes the module work, and despite this being a small wire, seems to feed the module without blowing any fuses.

I have stared at the wiring diagrams for quite awhile, and concluded it is fed by the No. 2 fuse in the engine compartment fuse and relay box. But the fuse is good. I have pulled all the fuses in both fuse boxes and found no bad ones......

Any ideas as to tracing this down? Or is there is another fuse or relay I am missing? The wire is coded red and blue which is consistent with the wiring diagram....