Pulsating Lighting
 

Can anyone tell me why my lights, interior & dash, pulsate while the engine is running? I have a 1966 Mustang with a 289 V8.

Thanks in advance. Terry

Would like to know myself also, since my 68 does the same thing.

I think I kinda know why this happens. If you are talking about the slow dimming and brightening that they do with the engine rpm, it could be a component in your charging system. But if you are talking about the really bright and dim pulsating that lights do sometimes, I heard that this was either a bad ground or a relay that is about to go bad.

Mine slowly dims and brightens with the engine RPMs. However, I have a new starter, alternator, battery, headlight switch, voltage regulator, solenoid switch, and all new wiring? Don't think anything on the car isn't new (ha ha). Doesn't bother me and runs great, just curious why the slight fluctuation in instrument panel lights with the RPMs. Could it possibly be I don't have enough amps on my battery or would that have anything to do with it?

I think it could be that your alt doesn't put out enough amps - I have the same thing going on with my 90 5.0. I have the regular oem alt and might go to a higher output, but it doesn't bother me really.