I have a neighbor who has a 2003 Cavalier with the 2.2 Ecotec engine and a
manual transmission which has an alternator problem. It puts out about 13V
which doesn't fully charge the battery.
It looks like you can remove the air duct for the intake and get the
Could someone elaborate on the difficulty and time to change out the
I cant be specific. I have seen those engines in other applications, and
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?
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.
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
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
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
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
Document ID# 862445
2003 Chevrolet Cavalier
Charging System Description and Operation
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 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.
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
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
. 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
. 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.
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