I had the same problem with my shadow. I had both tail light sockets and back up light sockets that were faulty due to a bad ground. I use a jumper wire and ran it to the grounding part of the socket to a good ground. When it fixed it I took the ground wire from the socket and soldered it to the side of the socket and it worked fine. The type of socket that this was used a 1157 or similar bulb
The fuel sending unit is sticking, or the wiring to the gauge is loose. These are the two most common causes of an erratic gauge.
Did U checked the turn ligths flasher, switch and wiring?
if your right turn signal does not work then it could be the switch if not then it could be a wiring fault! Could also be turn signal flasher or switch in steering column as stated above
On the 1979 B200 Sportsman V8 if the brake pedal makes all signal lights come on and hazards and flashers do not work on their own, it could be the flasher, but the culprit could also be a burned out bulb or a short in the wiring.
As such the hazards are limited to accidental electric shocks and fires
Try replacing the flasher. Inexpensive and quick/easy to do. If the turn signals will light up and only stay on, it's definitely the flasher, if not then the problem lies somewhere in the wiring, or the turn signal lever itself.
the flasher unit is either in fuse box, or is in wiring under dash
Remove the flasher retaining bolts from the headlight assembly bracket. Remove the wiring harness. Reverse the process to install the new flasher.
I don't know of a flasher TERMINAL. There is a turn signal flasher in the wiring under the dash next to the steering column and an emargency flasher that sometimes is in the fuse panel.
in the wiring harness
exactly where is the flasher relay
you would need to check for voltage past the flasher unit and before the flasher make sure the problem is not the switch, or the wiring after the flasher.