Any suggestions have 2006 with 36000 LS2 engine all stock service charging system light keeps coming on replaced battery and alternator cleaned throttle body only comes on at red light and in park not while driving cold start rpm at 700 rpm 14.4 volts on battery warm idle 625 rpm 13.6 volts horn works running out of ideas

 

Did you check for codes before doing anything? Check the HORN/Alt Sense fuse in the underhood electrical center to see if it is good. If the fuse is good then you need to dig deeper. The ECM turns on the alternator so you need to know whether not that is working. Not sure why you thought cleaning the throttle body would help.

Here is how the charging system works:
The generator provides voltage to operate the vehicle's electrical system and to charge its battery. A magnetic field is created when current flows through the rotor. This field rotates as the rotor is driven by the engine, creating an AC voltage in the stator windings. The AC voltage is converted to DC by the rectifier bridge and is supplied to the electrical system at the battery terminal.

When the engine is running, the generator turn-on signal is sent to the generator from the engine control module (ECM), turning on the regulator. The generator's voltage regulator controls current to the rotor, thereby controlling the output voltage. The rotor current is proportional to the electrical pulse width supplied by the regulator. When the engine is started, the regulator senses generator rotation by detecting AC voltage at the stator through an internal wire. Once the engine is running, the regulator varies the field current by controlling the pulse width. This regulates the generator output voltage for proper battery charging and electrical system operation. The generator F terminal is connected internally to the voltage regulator and externally to the ECM. When the voltage regulator detects a charging system problem, it grounds this circuit to signal the ECM that a problem exists. The ECM monitors the generator field duty cycle signal circuit. The system voltage sense circuit receives B+ voltage that is Hot At All Times through the HORN/ALT SENSE fuse in the underhood junction block. This voltage is used by the regulator as the reference for system voltage control. On vehicles that use a sense circuit connected to the voltage regulator, this circuit must be operating properly for the charging system to work correctly, when there is a charging system concern all circuits at the generator should be tested.

Some more info:
Charging System Messages
The driver information center (DIC) displays a charging system message the when the following occurs:
• The engine control module (ECM) detects that the generator output is less than 11 volts or greater than 16 volts. The DIC receives a serial data message from the ECM requesting illumination of a charging system message.
• The instrument panel cluster (IPC) determines that the system voltage is less than 11 volts or greater than 16 volts. The IPC receives a serial data message from the body control module (BCM) indicating the system voltage.


Bill

 

Thanks bill,there are no codes at all stored horn works fine put a brand new ac delco alternator and still got same message my mechanic who put new alternator in said I may need to flash the car, only reason I cleaned the throttle body was because my mechanic thought the car had a slight rough idle warm idle it's about 575-625 he seems to think idle is too low?

 

Fantastic description Bill.
The alternator on my 427 went south over the weekend and threw two codes associated with the alternator field circuits. Replacement ordered.

 

have you changed the plugs and wires?
sometimes the ignition wire next to the alternator can cause RF interference to the alternator, some have also noticed that aftermarket plugs also cause RFI.
does it happen when the cooling fan comes on ?
do you have a UD pulley? or is the factory one going bad?

 

Original wires and plugs and pulley moved battery terminal on alternator away from spark plug, when then fan kicks in the battery volts jump around between 12.3-13.4 at idle stays steady at around 14.2-14.4 while driving

 

Ditto this.

I get the warning message occasionally too. All it causes me to do is look at the Voltage gauge and continue on.

Never got the message until I installed NGK plugs and MSD wires.

If the alternator is charging and voltage is good, I'd just ignore the warning and cuss the engineers who decided it was a good idea to hang the alternator right next to the #1 plug wire.

 

I've been posting on this for years. Change the spark plugs.

 

Just the copper NGK's(TR6 specifically) that cause the issue not iridiums from your experience?

 

Thanks for everybody's responses,finally took car to dealer I could never find a code and my regular mechanic could never pull a code assumed plugs were original because wires were original and car only had 32k when I purchased boy was I wrong Chevy mechanic found a code p0621 tsb bulletin on that code check for aftermarket plugs sure enough E3 plugs,put in original plugs problem fixed

 

My service warning light came on a few times but everything seemed fine. Until the alternator started making a light squealing sound. Pulled the belt off, spun the alternator pulley, and found the bearings in it were making noise. Replaced it with a remaned one from AZ and everything is once again fine. I did notice that the one I got does have the clutch type pulley on it. It charges to a steady 14.4/14.5 volts.

 

Mine started giving that warning (at idle only) right after I went to an iridium plug

 

The NGK plugs are a known issue affecting the alternator....weird but true.