Hello everyone,
I am new to the forums and I recently purchased an 88 IROC 350 TPI. shortly after I bought the car I found that when I use the turn signals, the volt meter, temp gauge, fuel gauge and tach would bounce up and down while the turn signal was on. The normal reading on the volt meter was around 11 volts also. I also found that when the headlights were on and the dimmer switch was set for the gauge lights to work, I had the same problem. This time both turn signal indicators lit up as well as the high beam light. The only bulb that lit up was the one on the speedo too. However, when I would turn the dimmer switch down all the way the problem would stop and the gauges worked fine (I just didnt have lights on the gauges anymore).

From reading the posts on here I decided to check the ground wire under the dash next to the steering column. I scraped off the surface and reattached the two black wires and everything worked great! All bulbs lit up on the gauges and the turn signals worked fine with no interference. The volt meter was also back up to 13 volts.

2 days later the problem returned. The voltmeter dropped and the interference was back when I used the turn signals and the head lights....

I see that some of you guys have had similar problems.....What else should I check, Would it be a good idea to check all of the ground connections? Or could my problem be in the dimmer switch? Any help would be greatly appreciated here guys....