voltage problem?

[CoalBurner02]

Just picked up my first diesel. Im the 2nd owner and the truck was well kept. the truck has 155,000 miles. I noticed the other night that at an idle, all my lights flash from dim to bright. Its something you notice if you look closely. I think its a voltage reg.....any ideas?

[NoRalPh]

Put a meter on it and see what the voltage actually is doing. If it's a subtle "pulse" in the lights you see I wouldn't be too concerned, if it is more than that (looks like "flashing") you need to find out why...