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When your alternator was tested, was the voltage regulator also tested. This unit is most likely inside the alterator, but may be mounted on the firewall or splash tray somewhere.When your alternator was tested, was the voltage regulator also tested. This unit is most likely inside the alterator, but may be mounted on the firewall or splash tray somewhere.
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Defective B+ battery cable from Alternator to battery
Poor Charging System ground(s)
Defective PCM wiring/connection to Alternator
Defective PCM
Defective Voltage Regulator
Large Parasitic battery drain
Defective Battery and/or cables
Common Misdiagnoses
Battery
Starter
Check the condition of your battery cables - are they corroded/have broken wire strands? Also check where the negative battery lead attaches to the engine/bodywork.
Check all the wiring for breaks and tightness - a small earth wire can be loosened and retightened to create a better earth. Corroded power wires can struggle to supply the correct voltage - remove and clean whatever you can find.
It's unlikely to be your alternator as you say it has been checked - the voltage regulator is built into the alternator so it must be okay.
A parasitic drain can be difficult to find. Try switching off everything - radio, heater ... the next time you start the car. If you know somebody who has a voltmeter and knows how to check for a power drain .. ask them.
The link below shows a Saturn PCM (it may not be your actual model..). Check all wiring around the PCM
change alternator and maybe battery. Since the battery is pretty new, draining it like you say only took a year or two off its lifespan. Remember how your car acted this time, as most newer cars do the same exact thing when the charging system or battery needs service. In the future, you will recognize the symptom and know where to look before you get stranded.
At this point maybe both. The battery light comes on when the alternator is not supplying enough power to operate the vehicle, and the battery is being forced to provide the difference. This problem, if not serviced, will quickly drain the battery. Replacement of the alternator is most likely needed. Be advised that alternator manufacturer/re-builder will not warrant an alternator that is installed on a car with a dead battery. So have you battery checked out; if it is good get it charged first. If it's bad replace it along with the alternator and you should have no problems.
the battery light comes on to indicate there is a problem with the charging system, not necessarily the battery. With the engine running check for voltage at the battery. you should have more than 13.5 volts. Anything less than that and the alternator is not charging.
WHEN THE BATTERY LITE COMES ON THE DASH IT IS TELLING YOU THE VOLTAGE FROM THE ALTERNATOR IS WORKING, TO CHECK THE ALTERNATOR WITH A VOLT METER ON DC WITH THE ENGINE RUNNING YOU SHOULD GET A READING OF 13.5 TO 14.5 VOLT WHEN YOU TEST THE BATTERY TERMINALS IF THE VOLTAGE IS LOWER THEN 13.5 VO0LTS YOU ALTERNATOR IS BAD
Most likely you have a voltage regulator on the alternator going bad. That is why one test was bad then one test was good. The voltage regulator is most likely integrated into the alternator. Replace the Alternator and that should resolve the problems.
Sound like a bad alternator, if you had a battery light on it's bad. Start engine with an voltmeter check voltage at battery if you have less then 12.8 volts bad alternator, should have 13.5 - 14.5 volt's.Hope this was helpful.
Bad alternators straight out of the box are not uncommon. Replace it again and hope you get a good one. Make them test it on the bench before taking it out of the store.
When your alternator was tested, was the voltage regulator also tested. This unit is most likely inside the alterator, but may be mounted on the firewall or splash tray somewhere.
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