Had a problem where when I turned on the right turn signal, the tach & a couple other gauges would bounce in time with the signal. Turn on the headlights, the gauges would bottom out, right turn indicator light stayed on, turn the headlight ****, the tach would peg, think I lost the lights in the heater controls, too. Turned out to be a bad instrument cluster. Chased that down a while, swapped out the cluster, fixed. Just an FYI. 88 IROC.

John