When it rains hard my 2000 dodge gran caravans bat. Lt. comes on and i start losing my power steering why

Depending on the alternator installed, there is a 'de-coupler' as part of the pulley. If it's not new or hasn't been replaced with the alternator, that may be part of your problem. Additionally, if it is new with the alternator, I've seen many of these bad out of the box. We haven't had to replace too many alternators on these vans, most of the failures are due to the de-coupler and the dealer part is the best way to go.

wrong alt
goodluck

Believe it or not the firing order is 1-2-3-4-5-6, cylinder number 1 is the rear passanger side. The cylinders from left to right are 1-3-5 on the rear of the engine and 2-4-6 on the front of the engine. the coil block i numbered 5-1-3 on the rear and 2-4-6 on the front. I hope this helps.

Only one wire?? then its a ground wire, grounds a relay to energize the horn, disconnect the horn and see if you have voltage to it , if not it could be the relay, steering column not grounding, or a bad wire.

Try (repairpal.com) for estimate for your particular area. You may have to enter Grand Caravan to get the 3.8L engine .
I'm thinking 2 hrs.

It sounds a lot like the accessory drive belt was slipping. Check the tension of the belt. It should be hard to flip it upside down with your fingers. I would say the rain was enough for the power steering and alternator pulleys to start slipping.

old not as elastic
if it keeps sliping off try putting a hose clamp on it or replacing the hose

if it keeps sliping off try putting a hose clamp on it or replacing the hose

run the fault codes
check for problem MAF?VAF sensor and accelerator position sensor

how do you get it started again try giving it a boost if this works clean all bat connections and try again .if problem persists replace alternator hope this helps good luck