I'm thinking in the back of my mind that this is a comon problem but I am not realy sure where to start? When my turn signal is activated it pulls hard on the electrical system. Voltmeter drops with every blink, Engine RPM drops with every blink. I was thinking bad ground but being as the left and right lamps are grounded seperatly and it does not seem to matter whitch way you throw the switch, the outcome is the same. I have also heard the problem can be in the instrament circut board??? Any help would be great!

 

mine does this as well but i cant tell if the rpms drop cause my tach dont work, i was just gonna replace the altenator with a better than oem replacement one day

 

mine has always done that. i have even seen trucks in the same years do it.

 

Well I went thru all the grounds today and It did not change a thing. Went and got a new HD turn signal flasher and that DID correct the Long drawn out turn signal flash it used to have. It did NOT however solve the problem of the Volt meter and Tachometer twitching. I think I will try a different Circuit board on the back of the cluster and I will post up if that makes any difference. Seems like a lot of us have this issue with no resolve?

 

I have the same issue with my 91, don't know what the hell it is either

 

I had a bad problem with the right side bulbs not working, when remaining lights are on it pulls the guages down and right turn signal on the dash stays on, pulling the voltmeter down. It was a bad ground. I pulled the dash and attached a ground wire to the negative connecter on the tach (that the bulbs share with it). It fixed the problem. Maybe you can do the same.