96 Regal GS Battery light back on

[gshep]

RGGHHHHHH !!!! OK, after installing a new battery Saturday, the battery light came back on just like before, after a couple minutes driving. This began immediatley after a mechanic replaced the PCM for a no start. He even warranted the PCM and still the battery light came on. I have never had to jump start the car. I play the radio, and even the headlights are not dim at night, nor were they with the old battery.
Sooooo, I bought a alternator today. Salvage but bench tested at a local starter/alt shop and output was great. Around 14.2. Installed the alternator, test drove the car and like clockwork, the battery light comes back on. Went to the local Autozone and their tester showed no alternator output. So how does the battery stay charged?
I wanted to check the continuity of the alternator wiring but could not tell where the small red wire goes. The wiring diagram shows the red wire from the 4-pin alternator connector going to the starter I think. Is there a fusible link in line and if so where is it? Can I just run a straight wire and bypass the existing link? Remember, this has 188,000 miles and is mainly used by my daughter back and forth to school and work. Usually no more than 5-6 mile per day.

[BNaylor]

The fusible link (10 GA) is supposed to be at the starter then from the starter
to the battery positive.

[gshep]

Good morning and thanks. I was just reading my Haynes manual and it says that if the link is burned the car will not start and/or the accessories will not work. If this is true, my link must be good because the car always starts fine an all accessories work. It has been truly odd because I have not seen any sign of a weak battery. Could something have just caused a fault in the warning light circuit? Any other ideas? I am taking my voltmeter to work and will try to slip out to test the alternator myself sometime today and post the results.

[BNaylor]

Originally Posted by gshep

Good morning and thanks. I was just reading my Haynes manual and it says that if the link is burned the car will not start and/or the accessories will not work. If this is true, my link must be good because the car always starts fine an all accessories work. It has been truly odd because I have not seen any sign of a weak battery. Could something have just caused a fault in the warning light circuit? Any other ideas? I am taking my voltmeter to work and will try to slip out to test the alternator myself sometime today and post the results.

Yep, I agree. From what you are saying the charging system appears to be working. If that link was bad the battery would probably be deader than a door nail sooner or later.

It could just be a fault or wiring problem associated with the monitoring system and warninh light.

[gshep]

Just checked and voltage at battery with key off is 12v and with car running over 13v. So I guess I have been in the wrong direction. Going to see if I can return the alternator. At the same time this started, the low oil light started coming back on after going out at start up and than going back out again after a few minutes. I am beginning to think when the mechanic had the car and let the battery run down he blew sonethg recharging it. Anyway, back to the wiring diagram to see where these lights have a common connection.

[BNaylor]

Originally Posted by gshep

Just checked and voltage at battery with key off is 12v and with car running over 13v. So I guess I have been in the wrong direction. Going to see if I can return the alternator. At the same time this started, the low oil light started coming back on after going out at start up and than going back out again after a few minutes. I am beginning to think when the mechanic had the car and let the battery run down he blew sonethg recharging it. Anyway, back to the wiring diagram to see where these lights have a common connection.

Thats interesting. IMO the common connection point will probably be found at the Instrument Panel (IP). 12v volts is normally always on one side of the lamp and the sensors normally supply a ground to turn on the respective lamp. Not sure about the 1996 and under Regals but the '97 and up have a decoder module in the IP. It is a module thats contains various diodes in the form of a matrix for routing of the signals and for isolation purposes. Good luck and hopefully you'll get it resolved this time.

[gshep]

Well it's confirmed, now I have two good alternators. The salvage yard is at least willing to give me store credit and I don't have to swap theirs out and reinstall mine. I was told that sometimes unhooking the batterty for 2-3 hours can allow the system to reset so it's in the parking lot from now til lunch "resting". As a last resort, I will install a small voltmeter in the car and install black tape over the light.

[BNaylor]

Originally Posted by gshep

Well it's confirmed, now I have two good alternators. The salvage yard is at least willing to give me store credit and I don't have to swap theirs out and reinstall mine. I was told that sometimes unhooking the batterty for 2-3 hours can allow the system to reset so it's in the parking lot from now til lunch "resting". As a last resort, I will install a small voltmeter in the car and install black tape over the light.

Sounds like a good move to me. As long as you have confirmed everything else is working and the charging system is good why not.

[gshep]

Thanks, now all I have to do is pry my daughter out of my Grand Cherokee and teach her to watch a gage.