16.4V Charging Voltage???

[lightman02]

OK, so I have the battery light come on a year after I replaced the alternator which was from Autozone. I had a well know rebuilder check it out and he said the coill and regulator were pretty much toast. He also stated to check the batterty because the alternator was so toasted. I put in the rebuilt alternator and keep in mind the car always started strong. Battery is about 3 years old. I charged the battery and started the car and after 30 seconds I get the check charging system message. I checked the battery voltage and it is showing 12.2v when the car is not running. When the car is running I'm getting 16.4V to the battery, which I believe should be 14.5 range. So question is why is my voltage so high?? Could this be a bad battery or corosion of some sort causing it to provde more voltage then normal??? This was all done while the car was idleing. Or could my alernator still have an issue???

 

[Andrizzle]

Whatever it is, stop running the car until you figure it out. Have the alt and battery load tested. 16+ volts is well into the computer frying range.

 

[NYC LS8]

Bad voltage regulator. Not sure if that's controlled by the car's computer or if the alternator has a voltage regulator mounted to it or what. I'm sure someone here can clarify that, though.

 

[lseguy]

Dont know, but what I've learned is that those Duralast brand rebuilts are hit or miss. I've since learned to ONLY go with Motorcraft for the LS on critical parts.

 

[joegr]

Some info for the speculation:

The voltage regulator is internal to the alternator.
The voltage regulator is told by the PCM what voltage to regulate to.
The voltage regulator will not work correctly if the voltage feedback line to the alternator is not intact and well connected.

I'd suspect the voltage feedback wire first, the alternator/regulator assembly second, and the PCM last.

Gen II troubleshooting chart for overcharge...
http://deneau.info/ls/s6x~us~en~file=s6xe0003.htm~gen~ref.htm#PS2-C

 

[lightman02]

Some info for the speculation:

The voltage regulator is internal to the alternator.
The voltage regulator is told by the PCM what voltage to regulate to.
The voltage regulator will not work correctly if the voltage feedback line to the alternator is not intact and well connected.

I'd suspect the voltage feedback wire first, the alternator/regulator assembly second, and the PCM last.

Gen II troubleshooting chart for overcharge...
http://deneau.info/ls/s6x~us~en~file=s6xe0003.htm~gen~ref.htm#PS2-C

Thanks, this should be a big help.