Gizmo52

Just like the title says when the key is on and head light switch is pulled I have no lights at all in the rear. No running lights brake lights or license plate lights. But if I turn the key off everything comes on. The issue is only in the rear and I haven’t the slightest idea why it’s happeneing

Gizmo52

Change the switch and it didn’t fix the problem. Also checked power at all fuses both key on and key off and everything has power at the fuse panel.

j_martin

First thing I'd check is the grounds at the lights. With the switch off, the turn signals and brake lights will return through the tail and clearance lamps. With the switch on, the return would be to 12V, thus nothing will work.
The other thought that crossed my mind is a bootleggers rear lamp cutout relay.

Gizmo52

Good call on the grounds! They were carrying 2.8 volts when on and 3.6 volts when on the brakes. I have no idea who it was happening but I Cut all the grounds on the plugs and ran them from the plug to the chassis. I had to do it for Both tail lights and license plate light but all is good now! Thanks for the help!