Signs that indicate a faulty alternator or alt can be confusing. This is because these indications can include a variety of unrelated car problems such as a dead battery, a squealing serpentine belt, a warning light turning on, and a scent of hot wires or burning rubber. Because these problems can be caused by a number of things, it's important that you troubleshoot a possibly problematic alternator. There are a couple of ways to go about this, so check out the steps below.
Using a voltmeter
To confirm if this component is indeed the culprit, you can check it with an ohm meter , voltmeter, or multimeter. Here's how:
Step 1: Check the battery first.
Connect the voltmeter's black wire to the black battery terminal and the red wire to the red terminal. Take note of the reading. If it's above 12.2 volts, then the battery is working fine. If not, then it has to be charged.
Step 2: Rev up the engine.
Turn on the engine and rev it up to 2,000 RPM to push the alternator into high gear.
Step 3: Retest the battery.
While this component is in high gear, retest the battery with the voltmeter. This time, a good reading is between 13 volts and 14.5 volts. If the reading is lower or higher than this range, then the alt is faulty.
Another troubleshooting technique is by taking note of changes in volt and temperature levels and engine sounds while this component is running. Here's how:
Step 1: Check the alt gauge.
Turn on the headlamps, heater or AC, and other accessories and check the gauge for any decrease in the amp or voltage. If the reading goes up as you switch on various electrical accessories, it indicates a properly working component.
Step 2: Take note of unusual sounds.
While the engine is running, take note of squealing sounds that become louder whenever you switch on more electrical accessories and put more strain on the electrical system.
Step 3: Check the alt's temperature after switching the engine off.
Let the engine run for a few minutes before switching it off. Then place a finger on the alternator, taking note if the surface is very hot. If it is, the bearings or insulation components may be nearing the end of their lifespan. Keep in mind that bearings and insulation materials that are deteriorating is a sign that you need a replacement soon.
Step 4: Check the radio while the engine is running.
Turn on the engine again, rev it up, and switch on the radio. If the radio becomes fuzzy whenever you step on the gas, a likely cause is a faulty alt.
If you have experienced or observed most or all of the signs discussed in the steps above, your car's alternator needs to be fixed or replaced as soon as possible. Keep in mind that once this component goes bad, other car problems will arise or existing issues can get worse. Repairing or rebuilding this part is possible, but in some cases, installing a new one is a more practical approach.