How to Diagnose a Bad Alternator
It is important to diagnose a bad alternator if your car has one. It can disrupt the car’s electrical system because it is responsible for charging the car’s battery and electrical system. Damage to the car’s alternator can be caused by lots of heat or too much voltage.
- Park the car on a flat surface. Apply the parking brake for extra safety. Pop open the hood of the car. Look at the belt where the alternator is and look to see if it is loose or has splits in it. If it does the alternator cannot work properly.
- Put the key in the ignition and turn on the car and let it run for 5 minutes. Do not close the hood of the car because you will need to get to the battery once you shut off the engine.
- Hook up the voltmeter to the battery and start it. The volts should be around 14.2 volts while the car is in idle. You can buy a voltmeter at most auto stores.
- Open the driver’s side door and sit in the seat. Turn on the radio and headlights when the car in running and keep the voltmeter on the battery. Now check the reading again. It should be around 13 volts.
- Push the gas pedal to get the engine speed up to around 2000 RPM and have a helper check the voltmeter. This should increase the meter to somewhere around 14 volts. If it is lower or higher than the 14 volts, the alternator has a problem.