my tach in my 89 Iroc 5.7 dies randomly, it doesnt seem to affect the performance of the car, but it is annoying, it either goes to dead 0 or just red lines the whole time, and it takes the oil pressure gauge with it. Any suggestions?

 

You could try removing the instrument cluster and clean the contacts on the flexiable PC card, see if that helps. If that doesn't do it then the PC board on the tach itself probably has a bad component or a cracked solider joint.

 

I have a similar problem with my '85 Z28. It occurs only when I turn on the lights. If I turn the dash lights off and leave the headlights on, the tach works fine. Mine takes the tach, oil pressure, amp meter, and the right hand blinker light burns all the time when this problem arises.... My problem started last week and I haven't had a chance to get into it yet.

 

Maybe I should have done a search first.... Found one from sept. 2000 that seems to confirm the printed circuit problem. check this one out: https://www.thirdgen.org/techbb2/sho...ight=tach+dies