[wstaab]

Factory gauges with a MSD Street Fire Capacitive Discharge Ignition and MSD distributor.
I have checked the wiring per MSD and the Superformance MKIII wiring diagram from Blas Costagli and everything appears correct.
Problem: tachometer works until you turn on the instrument lights.
Light in tachometer illuminates and the tachometer reads “0”.
Turn off the instrument lights and the tachometer starts working again.
Tachometer has an internal bulb. Connector to the rear of the tachometer is properly seated.
All the remaining gauges work normal with the instrument lights on or off.
Any one seen a similar problem and a solution?