2003 Cavalier Alternator

I cant be specific. I have seen those engines in other applications, and some are more complex than others. I would guess about 30 minutes to one hour, based on the other ones I have seen.

You may have an entirely different situation.

Make sure you are testing the generator correctly. I can't say for the 2003 but the 2006 cobalt and my 2004 Odyssey have ECM controlled charging systems so I think that does also. You need the service manual to determine the correct check procedures. Why do you think the alternator is bad? Based on a simple voltage check?

"Woody" wrote in news:GcXFj.5325$ snipped-for-privacy@newssvr22.news.prodigy.net:

Because he has to occasionally jumper the car and the battery does not fully charge. A charger will quickly fully charge the battery and when the engine is running the voltage output is only about 13 volts. According to a parts place the regulator is built into the alternator and not ECU controlled. I can't be sure about the regulator but the 13 volts is the problem. It simply is not enough to keep the battery charged. Had a car in the past with this problem myself and it was the alternator.

Woody - you're dating yourself...

"Woody" wrote in news:GcXFj.5325$ snipped-for-privacy@newssvr22.news.prodigy.net:

I don't intend to recommend he change out the alternator without it being properly diagnosed but wanted to find if there was any obvious problem with the removal. A battery's voltage when fully charged is about 12.6 volts so 13 volts will not keep it charged. No factory manual is necessary to determine this. The only question is if the regulator not setting up the proper field current or a defective alternator. It is not possible to check the Alternator terminals until some air duct is removed. I called an auto electric service shop today and the guy said from about 60 to 80 bucks for the repair if the alternator is the problem. Will have to verify whether the regulator is indeed in the alternator or externally controlled and check the alternator terminals but it points to the regulator or alternator. thanks for the response

I am but it has come full circle as in my 2006 Cobalt service manual it is called a generator again..... And as I mentioned above it has a very elaborate charging methods depending on many environmental and engine/driving parameters. No more throwing a voltmeter on the battery and looking for 14+ volts as the output can be as low as 12/13 volts depending on the charge state of the battery that the ECM has detected...

Document ID# 862445

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Charging System Description and Operation

Generator The generator features the following major components:

The delta stator The rectifier bridge The rotor with slip rings and brushes A conventional pulley Dual internal fans The regulator The pulley and the fan cool the slip ring and the frame.

The generator features permanently lubricated bearings. Service should only include tightening of mount components. Otherwise, replace the generator as a complete unit.

Regulator The voltage regulator controls the rotor field current in order to limit the system voltage. When the field current is on, the regulator switches the current on and off at a rate of 400 cycles per second in order to perform the following functions:

Radio noise control Obtain the correct average current needed for proper system voltage control At high speeds, the on-time may be 10 percent with the off-time at 90 percent. At low speeds, the on-time may be 90 percent and the off-time 10 percent.

Circuit Description 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 PCM, 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 PCM. When the voltage regulator detects a charging system problem, it grounds this circuit to signal the PCM that a problem exists. The PCM monitors the generator field duty cycle signal circuit. The system voltage sense circuit receives battery positive voltage that is Hot At All Times through a fuse link that is connected to the starter motor. This voltage is used by the regulator as the reference for system voltage control.

Charging System Indicator The IPC illuminates the charge indicator in the message center when the following occurs:

. The PCM detects that the generator output is less than 11 volts or greater than 16 volts. The IPC receives a class 2 message from the PCM requesting illumination.

. The IPC determines that the system voltage is less than 11 volts or greater than 16 volts. The IPC receives a class 2 message from the body control module (BCM) indicating the system voltage.

. The IPC performs the displays test at the start of each ignition cycle. The indicator illuminates for approximately 3 seconds.

. The ignition is ON, with the engine OFF.