2003 Ford Windstar Issues

HI, My van started with the locks going crazy. Sometimes they will unlock other times you have to unlock the door from the inside.
Then I was driving down the road and the lights would dim then go regular and then really bright. Then the ABS and Brake lights would blink on and off.
The heater also went fast then normal.
Then It lost all power to the door locks and windows, windshield wipers, radio,dash lights, heater and then the tachometer and odometer went crazy back and forth all over the place. Then comes back on like normal.
Today the battery light blinks on/off.

We took it to 2 different garages to have the battery and alternator tested and they both came back OK.
Added a ground wire from the negative port on the battery to the body.

What else can we do and WHERE do you find the BCM? I found the FEM and REM but for the life of me can not find the BCM.

Any and all help would be appreciated. HELP ME PLEASE!!!

I had a problem where the battery was being drained over a week period of time. The car was only driven 1 time a week. Traced it down to the power lock system. If I manually looked the doors the car could sit over 2 weeks and would start up fine. This was not a Windstar but could be somewhere to start. Possibly a sticking lock mechanism.

This is most likely a bad alternator. A bench test will show them good but if they did a full load test, they'd see that the integrated voltage regulator has likely failed. I'd make sure the PCM didn't get water into the connector, and then try a new alternator before doing anything else.

My van is a '96 and doesn't have the BCM. The only interior module is the GEM, which is located under the dash on the driver side of the console. I've had issues with it where the functions it controls will intermittently become inactive. I was able to "repair" it by reflowing the solder connections to some of the ICs on the board.