So I have a 2004 Nissan 350z, bought the car with an issue causing low brake lamps and license plate lamps to always stay on even when car is off, I started with pulling the tail lamp fuse (fuse71 off ipdm) they still stay on, I tried using another ipdm since I saw water got on it and I was thinking maybe internally has a tail lamp relay judging by a wiring diagram I saw, they still stay on, even with the ipdm disconnected from the car with the battery connected they still stay on haha so all I can think of is either the ecu keeps sending out power to the wiring or somewhere in the wiring that goes to that circuit is touching power somehow, if anyone is dealing or has dealt with this problem and has any tips on executing this issue it would be greatly appreciated

 

Welcome, - but this isn't an issue common to Z33s. Any details on what kind of maintenance/repair history is with this Z? It sounds like a PITA electrical issue to track down, but I'd start by checking the interior wiring harness itself for splices or other signs of damage. Otherwise, installing a kill switch might be a possible fix.

 

Do you know if the car ever had a backup camera added? For sure someone has been into the harness somewhere trying to get power to the rear.

 

Sounds like a wiring hack job was done. Time to start pulling panels and looking for taps and tracing. I'm honestly shocked to hear that even after pulling fuses, you're still getting power to the tail-lights.
-Icer