troubleshooting charging system

[bd1028]

Thought somebody out there might be able to point me in the right direction.Driving to work this morning and battery lit up in the message center and has stayed on. installed new batteries about six weeks ago. so I grabbed an alternator from autozone and put on but light is still on and volts are reading lower than normal on the gauge.Truck still starts fine but I did notice that the windows are not going up as fast as normal.
2002 2500 Silverado
Ext Cab duramax

[bd1028]

Well I figured out the problem pcm was sending signal to alternator but no response so we replaced with another and everything is fine now.

[Quack_Addict]

IMHO, Autozone does not have a good track record for reman alternators for any models later than the early 90's. My brother installed 3 alternators from Autozone into his 1995 Trans Am and never got one that worked right. I got one from them for my 1992 S10 that was as dead right out of the box.

I have had a local starter/alternator shop mess up 2 alternators of mine prompting me to sware I will NEVER take them another alternator.

The first alternator they goofed was for my 1982 K5 Blazer with 6.2L diesel. They replaced the voltage regulator and within a week the thing went "full field" as they called it. It had the voltage gauge pegged on the high side. It smoked the fusible link to the starter and blew my radio before I could stop and shut the engine off.

The second alternator they buttered up was for my 2002 HD with 6.0L. The voltage regulator went out and as several years had passed since the K5 incident, I took it back to the same shop (they have treated me well on motors for snow plows, trim motors for boats, starters, etc since). They put a new voltage regulator into the alternator and it charged up to snuff but the battery light kept on coming on intermittently while driving. It turned out they had put the voltage regulator in for a 5.3L engine, which supposedly is different than for the 6.0L (or maybe it's just for the HD's with 6.0's that are different, I don't know). The second time around, they still didn't get it right - light still came on intermittently while driving. I got tired of being without a truck and ended up cutting my losses by spending >$200 at Car Quest for one of their reman alternators. I never had another problem with it.