My alternator light is on, ever since it has been on i have replaced the battery, the terminals, and te alternator, but the light is still on what elsed could the problem be?

charge lights work from a current flow either from the battery to the alternator or from the alternator to the battery. the opposing current flows will put the light out when each unit has the same voltage . So if the light is still on after the alternator has been replaced there are 2 checks to do . Check that the alternator is in fact charging correctly (dc voltage as well as 14 volts and next check is to see if the battery is any good and that the terminals are clean and tight. Best have it checked out at an accredited auto electrical shop.

wire in a big spotlitgh on the battery terminals while battery still wired in, it might jump start the voltage rregulator

firstly check with your car scanner ,read for fault code, as my experience the alternater fault due to leak in alternator regulator ,check with multimeter for your voltage, at least with light and air con on, it should at least 13.6volt.normally with alternator light on when engine running.conform alternator,replace one thank you

The battery light means your alternator is not charging, so if you continue to drive the vehicle your battery will eventually drain and the vehicle will stop.

You can test this by putting a volt meter across the battery posts. A fully charged battery should read 12.6 volts. Then start the engine and the voltage should increase to 13.5 to 15 volts. If you do not get this increase in voltage, then the alternator is not charging, which can be either the wiring to the alternator or the alternator itself being bad. Good luck :O)

The battery light staying on indicates that your battery is not charging either because of a faulty battery or a faulty alternator/regulator! Seek a second opinion as the diagnostic seems a bit dodgy when you have a lit battery light and your battery is definitely going flat!
If you have a multimeter, measure the voltage at the battery terminal with engine off: it should read around 13.8Volts and anything below 12 Volts is bad news!
With engine running, measure the voltage at the battery terminal again: it should read around 14.5 Volts - if it 13.8Volts or lower or above 15 Volts, you have a bad regulator/alternator.
Replacing an alternator does not require a lot of labor so it is virtually for the cost of the replacement alternator (consider getting a second hand or recondition unit - under $100?).
In all case, always clean up the battery terminals and clean/retighten all battery and alternator cables and terminals.

Hope it helps.

the alternator is a doodle to change ,when you know how ?? was it a new recon unit or a secondhand scrapyard job---- check for power to teh large terminal the start engine and disconnect neg battery terminal if engine stops alternator fault ,if engine keep running but red light still on then its warning light control fault which is built into alternator so change alternator .

If your battery warning light is on, then your alternator is NOT working okay. Rather, maybe the alternator DOES work, but the battery light can also come on if your battery won't charge.

Put a voltmeter to the battery terminals when the engine is running and rev the engine to a medium idle. Battery charging, (engine running) it should be about 13.5-14.5 volts. Engine off fully charged battery voltage should be 12.6 volts.

Quick test-engine running, disconnect the positive battery terminal from the battery- if the engine dies, there is still an alternator problem.

Hope this helps.

Alternator is not working correctly. You are getting less voltage out of it. The brushes are probably worn out on it. Have the alternator checked and replaced if defective.

You have a connection problem. The terminals need to be completely cleaned & tightened as well as the ends of the battery cables where the ground & the main power leads terminate. It's best to remove te Neg. (-) cable first & attach last when dealing with the battery.

Double check and clean the contacts on any small wires running from the Pos (+) terminal or from the connecting spot at the starter solenoid & make sure they are not broken or burned. A 12 Volt test light should help you find why the voltage isn't getting into the electrical system.

Lastly, double check the voltage on the battery to be sure it's fully charged, test your alternator to make sure your entire system is working properly make sure the battery is connected properly, some batteries have reversed post.

good luck

Have the alternator tesed to see if it's good, if both alternator and battery are good check the drive belt and tensioner for loseness and wear, the drive belt drives the alternator, it sounds like your alternator is having problems charging the battery, if both alternator and battery are good try changing the battery cables, good luck.