Is it my alternator, or?

From the symptoms, it sounds like the charging system is quitting and system voltage is going low. That will make computers do weird things. If you can catch it when the problem is occurring, use an inexpensive digital voltmeter to measure battery voltage while the engine is running. It must be between 13.75 and 14.75 volts. If it is low, a common cause is worn brushes in the alternator. They can be replaced for 20 bucks, but most people just replace the entire alternator. It would be smart to measure the two voltages on the two small wires on the back of it first to be sure that's the problem. One will have full battery voltage only while the engine is running. The other one must have less but not 0 volts. 4 - 11 volts is typical. If you find 0 volts, the brushes are worn.

The battery warning light isn't for telling when the battery is defective; it's for when it's not getting recharged while driving. That is usually the fault of the alternator. Typically the brushes wear down and cause an intermittent connection.

You can use an ohm meter to test the brushes. It can be done with a voltmeter too. Measure the continuity between or the voltage on the two smaller terminals on the back of the alternator. Voltages must be read with the engine running, not just with the ignition switch on.

I never replaced the brushes on a 2003 but on my '95 Grand Caravan that can be done without removing the alternator from the engine. I just did that on my '88 Grand Caravan daily driver a few months ago. That was an older, larger style alternator that had to be removed, but the whole job took about a half hour. That nine-dollar part was better than buying a whole rebuilt alternator.

In the future you should start a new question rather than piggybacking on this one. I am the only person who will get an automated e-mail directing me back here, and if I don't know the answer, none of the other experts will even see it or have a chance to help.

The voltages on the two smaller terminals might be different than what's described on that page. Chrysler had a REAL nice voltage regulator circuit since 1970 through at least 2000, then for who-knows-why they decided to turn it around and lose some very simple diagnostic characteristics. Instead of 12 volts and "something less than 12 volts" on those two terminals, I believe you should find 0 volts and "something greater than 0 volts".

Regardless, measure those voltages and holler back. We should be able to make sense of them.

Usually it's just the brushes that wear out. I recently replaced them on one of my Grand Caravans for nine bucks.