my lights flicker really fast. dash lights,brake lights, dome lights. everything
i took my truck to advance auto. they tested alternator and it shows charging is fine. even my volt meter stays at 14 but will slightly move back and forth. has anyone had this issue? can you help me?

 

Sounds like loose/corroded battery cables....everything going on-off-on-off and reeking havoc on everything.

 

my battery cables are clean. not rusted! no corrosion.

 

My second guess then would be a bad ground somewhere.

A big one like chassis to body or engine to chassis ??

 

I have an 06' Trailblazer that shows the voltage gauge lowering to about 12v. This only happens at normal operating temperature. I tested the voltage at the battery while running and I get approx 14.4 when running normal and 12.5-13 fluctuating when this situation occurs. This occurs intermittently during idle. When you raise the RPM slightly during the above mentioned issue the voltage raises back to normal. I thought it was the voltage regulator and changed the alternator, no luck.