: P0621 Code Batt not Charging/Svc Chrg Sys

12-23-09, 05:10 PM
I am working on a 2002 Deville. I has the battery light on and message on the DIC toggles between "Sevice Charging System" and "Battery Not Charging". The generator is putting out +/-14.7v and DIC says Voltage OK.

We took apart the connector on back of the genearator and it is nice and clean, all connectors are clean. I have read about the code and it is "Generator L-Terminal Circuit fault" Any Ideas?

12-26-09, 02:40 PM
Since I posted the original message, the car has been starting to have other electrical issues. The voltage now spikes to over 16.0v. I am now fairly sure the voltage regulator is probably bad. Looks like time to replace the generator!

12-26-09, 02:50 PM
seems you have found the issue.
both times my alternator went out ( on my 94 and 2000) i got them rebuilt for about 60 bucks, see if you can find a local guy that rebuilds starters and alts.
the voltage regulator is what controls your output as you know, also might want to check the sensor wire ( a two wire plug on the back) be sure it is pluged in.
To be certaint that it is the alternator. put a AC volt meter across the battery terminal with the car running and see the AC voltage across the battery posts.. it should be no more then .25 volts. if it is then your regulator is def. gone.
To pull out the alt. you need to remove one of the cooling fans and remove a lower frame plate ( 2 bolts i do beleive ) and then drop it out of the bottom. i put a piece of cardboard on my rad so that when i was trying to wiggle out the alt. it wouldnt dent the radiator.

12-29-09, 08:00 PM
Just spent the day changing the alternator, and no difference. Battery light still comes on after about 30 sec of running, anong with the messages on the DIC. Seems it has to be a faulty wire. Any idea where we should start looking. BTW, the old alternator tested out fine at Auto Zone.

12-30-09, 11:47 PM
Was it a new alternator or a rebuilt? was it A/C Delco or aftermarket.

BTW, Just got back from Eagle River. Nice early start to the snowmobile season for a change.