Van alternator/voltage regulator

Just fit a exchange unit ,,the electronic regulator is faulty end of story .Plus voltage drain could be a diode packed up ,just fit a exchange unit ,

have an accredited auto electrician check the out put of the alternator . Check the condition of the drive belt and the tension of the belt. place a multimeter across the battery terminals and it should read battery voltage . Increase rpm to around 2.000 rpm and the reading should go up to 14.5-15.5 volts. It doesn't move I would suspect a faulty regulator or diode pack in the alternator.

sound like faulty alternator voltage regulator. check alternator out put at battery with engine idling should be 13.5 - 14.5 volts at 2000 rpm if not lower you have faulty voltage regulator.also check alternator drive belt and check alternator for loose wires.besure turn off radio before disconnecting negative battery cable to keep from locking out radio losing code.

Your car's symptoms (voltage fluctuations under load that shouldn't happen) seem to
strongly indicate that your voltage regulator has failed. The voltage regulator is the component
that regulates voltage coming from the alternator, and which is supplied to the rest of the car.
Your new belt tensioner indicates to me (and should have to your mechanic) that the
alternator and/or voltage regulator weren't able to operate properly, and a faulty belt tensioner
has killed more than one car's alternator/voltage regulator.
Your do not need new headlights. Do fix the turn signals.

In the 2005 Sunfire, the voltage regulator is an integral component of the alternator, and is
not separately serviceable. So your 2005 Sunfire needs a new alternator.

2005 Pontiac Sunfire Alternator - Duralast Part Number: DL2305-15-4 $199.99 available at:
http://www.autozone.com/autozone/parts/2005-Pontiac-Sunfire/Alternator/_/N-jmqtpZ93xme

The national parts chains (Advance Auto Parts, AutoZone, Pep Boys) will (for free) administer
a "Charging System Test." Which will telly you for sure that your alternator/voltage regulator
is bad. Do this before replacing alternator, since its a pricy part in the 05 Sunfire.

Just in case, Here's the 2005 Sunfire manual entry on (a) Diagnosis & testing the alternator, and
(b) replacement of the alternator

Alternator replacement is a do-it-yourself project, though you may need to get a
"Serpentine Belt Kit" on your favorite parts store's loan-a-tool program to remove/re-install the serpentine (drive) belt.
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Diagnosis & Testing - 2005 Pontiac Sunfire Alternator


Alternator Load Test

1. With the engine running, turn on the blower motor and the high beams ( or other electrical accessories to place a load on the charging system).

2. Increase and hold engine speed to 2000 rpm.

3. Measure the voltage reading at the battery.

4. The voltage should increase at least 0.5 volts from the voltage test. If the voltage does not meet specifications, the charging system is malfunctioning.
NOTE
Usually under and overcharging is caused by a defective alternator, or its related parts (voltage regulator), and replacement will fix the problem; however, faulty wiring and other problems can cause the charging system to malfunction. Many automotive parts stores have alternator bench testers available for use by customers. An alternator bench test is the most definitive way to determine the condition of your alternator.




Alternator No-Load Test

1. Connect a tachometer to the engine.
CAUTION
Ensure that the transmission is in Park and the emergency brake is set. Blocking a wheel is optional and an added safety measure.


2. Turn off all electrical loads (radio, blower motor, wipers, etc.)

3. Start the engine and increase engine speed to approximately 1500 rpm.

4. Measure the voltage reading at the battery with the engine holding a steady 1500 rpm. Voltage should have raised at least 0.5 volts, but no more than 2.5 volts.

5. If the voltage does not go up more than 0.5 volts, the alternator is not charging. If the voltage goes up more than 2.5 volts, the alternator is overcharging.
NOTE
Usually under and overcharging is caused by a defective alternator, or its related parts (regulator), and replacement will fix the problem; however, faulty wiring and other problems can cause the charging system to malfunction. Many automotive parts stores have alternator bench testers available for use by customers. An alternator bench test is the most definitive way to determine the condition of your alternator.


6. If the voltage is within specifications, proceed to the next test.



Voltage Test

1. Make sure the engine is OFF , and turn the headlights on for 15-20 seconds to remove any surface charge from the battery.

2. Using a DVOM set to volts DC, probe across the battery terminals.

3. Measure the battery voltage.

4. Write down the voltage reading and proceed to the next test.



Removal & Installation - 2005 Pontiac Sunfire Alternator


2.2L (VIN 4) Engines

1. Before servicing the vehicle, refer to the precautions section.

2. Remove or disconnect the following:

Negative battery cable

Accessory drive belt

Alternator mounting bolts

Alternator electrical connectors

Alternator





To install:

1. Before servicing the vehicle, refer to the precautions section.

Alternator. Torque the upper bolts to 37 ft. lbs. (50 Nm) and the lower bolt to 22 ft. lbs. (30 Nm).

Alternator electrical connectors

Accessory drive belt

Negative battery cable





2.2L (VIN F) Engines

1. Before servicing the vehicle, refer to the precautions section.

2. Remove or disconnect the following:

Negative battery cable

Accessory drive belt

Alternator mounting bolts

Alternator electrical connectors

Alternator





To install:

1. Install or connect the following:

Alternator. Torque the bolts to 16 ft. lbs. (22 Nm).

Alternator electrical connectors

Accessory drive belt

Negative battery cable

SOUND LIKE ALTERNATOR,FIRST CHECK ALTERNATOR DRIVE BELT MAKE SURE BELT NOT LOOSE AND DAMAGE AND BELT TENSIONER BAD,CHECK THE ALTERNATOR WIRES FOR DAMAGE.CHECK ALTERNATOR VOLTAGE WHILE ENGINE IDLING SHOULD BE 13.5 - 14.5 VOLTS. IF NOT ALTERNATOR VOLTAGE REGULATOR FAILING. FIRST TURN OFF RADIO IF YOU DISCONNECT NEGATIVE BATTERY TO REPLACE ALTERNATOR BECAUSE THAT WILL KEEP YOU FROM LOCKING OUT RADIO AND LOSING THE PLAYING CODE.

LOSING POWER WHEN RUNNING COULD BE LOOSE BATTERY CABLE.FAULTY ALTERNATOR.NOT CHARGING BATTERY.CHECK BATTERY VOLTAGE SHOULD BE 12.6 VOLTS.WITH ENGINE RUNNING ALTERNATOR POWER OUT PUT SHOULD BE 13.5 - 14.5 VOLTS WITH ENGINE RUNNING IF NOT ALTERNATOR BAD.CHECK ALTERNATOR BATTERY FEED WIRE CHECK ALTERNATOR VOLTAGE REGULATOR WIRES AND CHECK ALTERNATOR FUSE AND MAKE SURE DRIVE BELT NOT LOOSE.BESURE TURN OFF RADIO BEFORE REMOVING NEGATIVE BATTERY CABLE TO KEEP FROM LOSING RADIO CODE.

It may be that the light is being tripped due to an "over voltage" condition. The faster you spin the alternator/engine the higher the voltage output of the alternator. I would test the voltage coming out of the alternator. It should be at about 14.3v or so max. If it gets into the 16v+ range when you increase the engine RPM then the voltage regulator has failed and needs to be replaced.

when you say car lost power bought a new battery.sound like alternator not charging battery.with car running your voltage at battery should be 13.5 volts or 14.5 volts it not alternators need replacing.have garage replace alternator if faulty because 1993 to 1994 cars if you disconnect battery car would lose memory causing car not to idle.the car will stall out at a stop light or stop sign whole lot.it would relearn itself but the stalling out dangerous around a lot of traffic.

fix the idle speed to 850-900 rpm
check the alternator and voltage regulator as the voltage should read 14.5-14.8 volts dc at 1000rpm or higher regardless of what is running
have it bench tested by an accredited auto electrician

The voltage regulator is having a problem. It is built into the alternator. You should take it to a local parts store that does free testing, and have it tested out.