very strange third brake light

[Chad]

i just installed my new led third brake light. it appears to work fine. i ride down the road and look in the rear view and it doesn't work. i finally figured out what it is doing, every time i open my door it comes on if i have it pressed. but only if my dome lights are on. I've looked and tested all the wires i can think of. i just can't figure it out, any suggestions?

 

[capricefrk013]

Could have something to do with the cargo lights. I have had to re-wire many LED tail lights in the past because they werent wired properly when built. check the wiring on the light and make sure its correct.

 

[1990GMCSIERRA]

maybe u just have a cargo light and not a third brake light,,my 90 is just cargo no brake