I had some time to mess with this....
The one on the front mounted to the rad support , I removed it , looks clean I sand papered it anyhow and re installed. No change
I have 2 heavy wires( not stock) from engine block to body.
The rear bulbs /running lights the sockets on the taillights are grounded to the housing right? They all work function normal so grounds should be good right?
Rear side marker lights were is the ground for them? Tail light sockets as well?
Something new I noticed....
When I first switch on the marker lights the right signal on the dash is bright for a split second then goes dim like I mentioned before.
Even though the turn signal switch is relatively new ( 5 years old, ignition switch in steering column replaced same time) it could still be bad right?
I put moved the battery to the trunk last spring but I had this same issue before I did that.