Has anyone ever figured out why the gas gauge moves in time with the turn signals? I have searched the net for solutions, but only found questions.
I have noticed that it is mainly the 97's that have this problem. So that must mean it has something to do with the fuel level buffer module that only the 97's have.

 

My battery gauge moves with blinkers

 

I've worked on several cars through the years that did this. The most common problem was an alternator on it's way out. It would have plenty of voltage but the amperage was way down. The other problems that caused this were a bad ground somewhere so it was grounding out with the turn signals or low voltage from a bad connection.

I'd pull the alternator and have it bench tested. Also spin the shaft and see if the bearings are making any noise. I replaced one that was a stinker to get to and it tested good but the bearings were howling. It cured the problem as when they got hot, the bearing caused drag and it affected the amperage.

 

Cant be the alternator, I have a new AD244 that my friend built for me. It was bench tested before we installed it. I also have a new battery and the big 3 wiring.
I tried another buffer module circuit board and that did nothing.
I guess next will be checking the grounds and studying the wiring schematics.
I might also pull the pump out, I have a trap door I made so that's not a problem.

 

my sonoma did something like this. i did the big 3 and it fixed it. Interesting..

 

My 97 did this for years... fuel gauge also moved when you turned the headlights on and off. I just figured it was a grounding / wiring issue shared with the tail lights and fuel pump. Never got any worse so i just left it.

 

I am having the same issues. The Fuel gauge jumps with the blinking turn signals, jumps when turning on any lights or accessories and when stepping on the brake peddle to activate brake lights. I have checked all the grounds I can locate and they seem fine. I also replaced battery and alternator. I replaced the fuel pump and sending unit about 3 years ago to correct an issues with the fuel gauge not reading correctly with an AC-Delco one. Then 5 months later the fuel gauge stopped reading properly again. It would show 1/4 - 1/2 tank less than it actually has. I replaced just the sending unit part with one from eBay because I got tired of spending money and the place I got the AC-Delco one from wouldn't honor the Warranty. Once again the fuel gauge is reading about 1/4 tank less than whats actually in the gas tank and now this issue for the past year with the gauge jumping with changes in lights/voltage. Has anyone ever solved this mystery? Replacing the fuel sending unit seams to be a temporary fix.