Can an alternator pass a test and still be bad?
The only way to know if an alternator is good or bad is to bench test it on an alternator test stand. Charging output can be tested on a vehicle with a digital voltmeter. If an alternator can produce normal voltage and current during a bench test, the problem is not the alternator but something else on the vehicle.
Can an alternator test good with a bad diode?
* To check for a possible bad alternator diode, switch your voltmeter to a low setting on the AC (alternating current) voltage scale. * With the engine running, touch the meter probes to the battery terminals. Any amount of AC voltage would indicate a bad diode, so you’ll need to replace the alternator.
What’s the best way to test an alternator?
Tools for Testing an Alternator There are two tools that can be used to test an alternator. One is the battery and charging system tester while the other is the voltmeter. The battery and charging system charger can detect whether there is a problem with the charging system of a vehicle.
What happens if you have a bad battery and alternator?
The dashboard lights may also dim even while the car is running. Both the battery and alternator are components of the car’s charging system. As such, issues with one inherently affect the other. Your vehicle may be able to function for a short time with a faulty alternator, depending on its unique power requirement.
Why does AutoZone test the alternator and charging system?
Keep in mind, when you test your charging system while the car is running, or AutoZone does the same, the system voltage is being tested at the battery, and if it’s not getting a charge, the test cannot determine why. Either the alternator itself is at fault, or the wiring between it and the battery are.
Can a worn alternator cause a voltage drop?
A worn, loose, or damaged connector can cause a massive voltage drop. If everything appears fine, the alternator should be removed and bench tested, which can be done for free at AutoZone. What if the Alternator Tests Fine?