Why does my alternator show a check engine light?
Additionally when an old battery is replaced the alternator will show a high state of charge because a new battery requires less effort to maintain than the aged battery, this may cause a check engine light. This will require a charging system reset using a code scanner capable of this task.
What happens when an alternator fails in a car?
When an alternator fails not only will the battery light come on but it can cause the check engine or service engine soon warning lights to come on. Never disconnect the battery while the engine is running to check the charging system.
How can I tell if my alternator is weak?
Before you test your alternator, here are some signs that your alternator might be weak: Your battery light is illuminated on the dashboard. Your engine is cranking slowly or won’t crank at all. The battery, headlights, and interior lights seem weak. The alternator is making rumbling or squeaking sounds.
How do you test the voltage of an alternator?
You can do this by using your voltmeter to run “voltage drop” checks across the connections when the engine is running. To perform a voltage drop test, set the voltmeter on the 2-volt scale and touch the positive and negative test leads on opposite sides of a connection.
What should I do if my alternator is not working?
The first course of action is to check the wiring carefully that runs between the alternator’s main power wire and the battery. 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.
How can I tell if my alternator is charging?
The alternator is charging if the battery voltage stays above 13 volts with the engine at 2,000 rpm and all accessories on. Check the alternator gauge. If you have a volt/amp gauge, it will read the alternator output for you.
Do you need a multimeter to check your alternator?
A multimeter measures voltage as well as other electrical properties such as current and resistance. You want to measure voltage when you’re checking your alternator. Check the battery first. The battery is needed to start the vehicle, which, in turn spins the alternator at sufficient speed to keep the battery charged.
Can You bench test an alternator at AutoZone?
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? Electricity is frustrating, or at least it can be.