What happens to the gauge on the dash when the lights flicker? How fast does this happen? Constant flickering many times per second or do they get brighter for a while, then dim for a longer period of time, say half a minute or more?
If the gauge is also going up and down, use an inexpensive digital voltmeter to measure battery voltage while the engine is running. You should find a steady 13.75 to 14.75 volts. If it bounces down to near 12.6 at times, suspect worn brushes in the alternator. There's a verification test that involves measuring the two voltages on the two small wires on the back of the alternator. The brushes can be replaced separately but most people just replace the entire alternator.
Rapid flickering is often due to the normal ripple that alternators produce not being filtered by the battery. This is a huge problem on GM vehicles, but on Chryslers the solution is just to replace the battery.
The lights may also dim enough to notice when the radiator fan or air conditioning compressor kick in. The AC compressor runs in the winter when you select the defrost mode. That is to remove humidity from the air before it gets blown onto the cold windshield where it would condense and cause fogging.
Saturday, January 29th, 2011 AT 11:27 PM