01 Grand Caravan sport w/ 3.3L and 41TE
I shall begin my listing out the gremlins I can remember off the top of my head:
1. HVAC controls default to PWR-ON, AC-ON most of the time when IGN is turned to run. This is regardless of how it was configured prior to removing the key.
2. A few times, the BCM has had to be rebooted(pulling and replacing its fuses); because of a suddenly-on "TRAC OFF," ABS, and Airbag light, that would not turn off. During this, the HVAC controls would not respond to input.
3. As of today, my mom says the battery light was on. I could not reproduce it when I got the van to look at it. According to my multimeter, I had 11.7 volts from the battery with engine off, headlights on(was dark, needed headlights on to see multimeter). With the engine running, I was getting between 13.95 and 14.24 volts at the battery. i noticed some oddities in the behavior of the vehicle, though.

• The engine temp guage was only at the first mark at that time, yet the radiator fan was still turning on.
• The electronic solenoid in the steering column that unlocks the shifter lever was treating the headlight switch the same way as the brake light switch. Normally, pressing the break pedal makes the solenoid unlock the lever. Somehow, when the headlight switch is moved to parking lights or beyond, it will also cause the shifter to unlock.
• With the engine idling(smoothly, for the record, albeit at a higher speed as if it thinks it's still cold), HVAC off, headlights on, I can still see the headlight brightness wavering as if the voltage isn't steady. Additionally, with the engine running, the blower motor draws enough that it dims the headlights further while it's spinning up(takes more juice to get it moving and all that). I would not expect to be able to see the headlights dim from the blower motor spinning up at all, much less with the engine running.

The alternator is "new." It's a reman unit from Ultima, sold by Oreilly's. I replaced the stock alternator with it back in June this year. So I'm hoping it's not that. tomorrow when it's light I will be double checking the connections ot make sure they haven't come loose.


Failing that, my next guess is the BCM itself. I don't know how to get to it though, and I doubt I'd be able to replace it completely DIY. From what I can tell this van does not have the SKIm system. The ignition cylinder had to be replaced many years ago, and the current ignition keys are chipless(and for that matter, gripless, just the metalkey).


Second opinions would be much appreciated. If needed I can go get a video of as much of these behaviors as I can.

 

If you're getting less than 12vdc with everything off I would at least charge the battery over night. If the battery is old I would just replace it. Best test is a free battery load test at any parts store. A weak battery unable to take loads could account for several of your problems.

You're not there yet but if it comes to it here's how to remove your BCM:

 

Test complete, O'Reillys says the battery, alternator, and starter all pass.