charging problem need help

I have a 1998 jgc 4.0l. that sometimes will charge sometime it doesnt.
the battery gauge stays at 14v when its charging good, next it maybe just right below 14v, but the gauge also goes all the way down and the check gauges light will come on. I checked battery voltage with my multimeter while the gauge was not working and there is no output from alternator. I guess what my question is could this be the pcm or maybe battery temp sensor,
ground problems,bad cluster. Im not sure where to start looking.:banghead:

I had this problem in my 98 about a month and a half ago. When I got out of the carwash it did it, the CHECK GUAGES on the dash was on, the volt guage was al the way down and the CHECK BATTERY message came up on the VIC. Got home and shut it off and played with the wiring at the PCM blew the harness of turned the jeep back on and it was good again - so I thought maybe water sprayed the PCM and it was causing a problem then about a week later it did it again. I replaced the ALTERNATOR and haven't had a problem since.

thanks for info. I am going to put a new 1 on today. hopefully this fixes my problem.

Since its a I6, I would bet on a weak belt tensioner.

I have a 1998 jgc 4.0l. that sometimes will charge sometime it doesnt.
the battery gauge stays at 14v when its charging good, next it maybe just right below 14v, but the gauge also goes all the way down and the check gauges light will come on. I checked battery voltage with my multimeter while the gauge was not working and there is no output from alternator. I guess what my question is could this be the pcm or maybe battery temp sensor,
ground problems,bad cluster. Im not sure where to start looking.:banghead:

new altenator fixed it drove about 450miles no trouble yet.