1992 Plymouth Voyager Alternator not charging

does the car shut off when this happens?

No, it does not shut off when the "check gauges" light comes on and the voltage meter drops. When I the light came on and the voltage dropped, I parked and turned the car off myself.

I suspect that the crank position sensor is faulty, but let me ask you this, how long ago did you change this alternator,?,it doesnt necessarily mean that because the alternator is new or rebuilt that it cant be faulty or will become faulty in a short period of time, did you see this 'new alternator " put in?

The "check gauges" light came on within 15 minutes of the alternator being replaced. I took the van out for a test drive; about 5 minutes into the drive, the light came on and the volltage meter dropped, but the van continued to run. I was less than a mile from home, so I turned around and came home immediately, not wanted to get stranded. I purchased the alternator, figuring to do this repair myself. I ended up having a friend who is a mechanic do it for me. I watched him put the new alternator in so I know it actually is the new one and was done correctly.

so even with the new alternator that your friend put in, is still doing this thing with the gauge? and this is number two since you took it to the shop? . what about the battery, is the battery accepting the charge? bring it to autozone and they will test it for free. I also have info on how to check it if you wish, but autozone is the best thing to do., Im thinking the battery may be the problem

https://www.2carpros.com/how_to/battery.htm