I have a 98 5.2, 4x4, SLT. Here's the history... Back in December wife was going to work and the check gauges light came on, radio quit, heater quit then truck shut off. I could jump it but it would just die again, I changed batteries and drove it home. I checked the truck with a volt meter and it wasn't charging. I removed the alt and took it to town to have it checked, it was good. I went home and reinstalled it, charged the battery and everything went back to normal.

No more problems til July, same exact issue, check gauges light on, a/c died, truck quit. Again I checked the truck with voltmeter and it wasn't charging, took alt to town it checked good. Reinstalled it and everything was fine.

Now a month later it did it again. Have tried different batteries, all connections are good and clean, cables are good, what else is there other than PCM.

 

check the relays and fuses in the black box behind the battery (PDC), but i would replace the alternator even tho it tests fine, those tests are not perfect by any stretch, and these trucks are VERY picky about voltage to begin with

 

again I disconnected the alt for a couple of hours and it's charging again... Checked all the fuses and relays and everything seems good. All connections are clean, no corrosion anywhere. I'm baffled.

 

The voltage regulator for the altenator is in the ecm, at least for the 5.9l. If, it stops charging, you may have to replace the ecm.

 

It's just odd that it resets after I reset the PCM... By the way mine is a 5.2

 

You may want to ck the dealer for a flash update,there could be one for the charging system.