Electrical problem

[chevy572]

I have a 93 ford aerostar and the headlights as well as radio pulsates getting bright then dim and my voltage gage fluctuates as well like if I put on the blinker everytime it flashs the gage swings a little. I had the battery and alternator tested and both check out good and both are only 2 or 3 years old so what am I looking at as a cause?

[justen]

possibly a bad ground, I also seen similar things like the alternator not grounding out or the chassis ground from the firewall to the engine block. Check your battery connections, and maybe do a test on the battery cables and make sure they are ok as well. Make sure your getting around 14 volts when the engine is running.