Do you know of another FB in the area that you can compare with? Also have a nother set of eyes look at it. Your grounded at the trunk as well? Might have to review the electrical systematics to better understand what's going on.
We need to isolate where the power is coming from (failed circuit). If the car is on, headlights are on then turn off ignition car & lights stay on. At this point try this:
Unplug each headlight starting from LH to RH side to see if engine quits.
If the car quits you probably found the circuit problem.
Also, how are you front signal lights doing. They are buggers to keep grounded. Ground them with a wire clipped to the frame to be sure they are grounded.
Front turn signals work properly, both running and turn function.
I will need to set aside some time this weekend. I think your idea of disconnecting the lights one at time is a good starting place. I do not think it is in the front of the car though as I recall completely disconnecting the front light harness and still had the rear arrowhead issue. This was prior to discovering the not being able to turn off problem though. I think the two issues are related.
As for trunk grounding, I do not recall having any specific ground wire attached anywhere. I do have the pointed metal ground bars on each of the arrowhead indicators. I thought originally that may have been the issue so I ordered them.
I was under the impression that if the lights did not have a good ground, they would not work anyway. All lights work, just not as intended. As I mentioned before the rear arrowheads work when they should. However, they ALSO work when they should not, when the light switch is in the off position and the dimmer switch is turned to the on position. They are even dim-able this way. The ignition does need to be in the on position for this to happen.
68' Firebird 400 convertible, numbers matching, solar red w/ deluxe parchment interior. 66' Pontiac Ventura Hardtop 66' Pontiac Catalina Convertible
