My dash lights seem get brighter and darker with the speed of the engine. It seems to happen the most when the Headlights are on. I dont really notice it with the headlights off. The Voltmeter seems to hold steady at 13.5V.

Any ideas what could cause this? I was thinking voltage regulator on the alternator or a corroded alternator cable or maybe a bad headlight switch...

Thanks

 

This can be caused by either 1) voltage drop due to a poor connection (high resistance) to ground, or 2) a faulty voltage regulator, or 3) a failing battery.
If you have a digital multimeter (don't rely on the dash volt guage), connect across the battery terminals with the engine off and check the voltage (v) - should be 12,6v for a fully charged battery. Start engine & check (v) - should be +/- 13.5-14.2v. Finally switch on headlights and check (v) - should still maintain 13.5-14.0 volts.
Another symptom of a poor voltage regulator is when your lights "pulse" @ engine idle.

 

Thanks Stephen.
The battery was replaced 6 months ago so I doubt it is the problem. I think the lights may be "pulsing" @ idle like you mention. I will confirm and will run the tests as you suggest.

Replacing the voltage regulator and the cables to the alternator seems like a painful process, at least from the DIY on RennTech.