Your motor vehicle's alternator has the responsibility of charging your car's battery, as well as energizing its electrical system when the car is running. When the alternator fails to do this particular job well, your car will gradually lose electrical power. The engine will eventually stop running because of the insufficient voltage it is getting to operate the ignition system. The result? You may find yourself stranded on the roadside!
When to Check Your Alternator
Whenever your battery warning light is on, or you recently replaced your battery or alternator, you need to test your voltage output. Testing is also essential if you hear a buzzing radio sound through your speakers. This may indicate alternator diodes gone bad, and leaking AC voltage.
If your car battery is overcharged, it will trigger a chemical reaction that will emit a noxious sulfur-like smell. This will indicate a voltage regulator failure that paved the way for the overcharging of the system when this happens. Your battery indicator light will not only turn on. The "service engine soon" as well as the “check engine” will also turn on.
If you need to check the charging system, it is never a good idea to disconnect the car battery while your engine is still running. This may trigger a major electrical system malfunction like a main computer short circuit. Before 1976, it was common practice to remove the battery cable for testing the charging system.
The battery is utilized as an electric shock absorber that helps stabilize the system. If you disassemble the battery cable, it will trigger a voltage spike that can potentially cause damage to major electrical components such as the computer. Thus, this is no longer done for motor vehicles today.
As mentioned, the alternator helps in powering all your car's electrical systems.
It is, therefore, a good idea to be aware of some simple tests, and knowing the early indications of alternator malfunction to avoid a car breakdown.
Having said that, we’re providing a detailed step by step guide on how to check the alternator of your car.
Things You Need, When Checking Your Car’s Alternator
Before proceeding, you need first to gather the materials you'll need for testing your alternator:
- Voltage meter or digital multi-meter
- Rubber hose (around 3’ long)
- Safety glasses
- Wheel chocks
Testing Your Alternator with the Car Engine Off
Step 1: Prepare for the test.
Step 2: Find the alternator.
Step 3: Check the drive belt of the engine.
Step 4: Watch out for unusual engine noises.
Step 5: Test the alternator with the engine turned off.
Step 6: Test the alternator with the engine turned on.
Step 7: Finish up.
To make sure that everything for your car is fine, use an obd2 scanner to diagnose the problems.
If the results of your tests show regular voltage readings, but problems such as a discharging battery, battery warning lights turned on, or car electrical systems issues persist, you may need to perform further testing. It is a good idea to seek the assistance of an expert mechanic who can perform a better job of testing or replacing your alternator.
Simon graduated with a Mechanical and Electrical Engineering Degree. He has over 20 years of servicing experience in both Japanese and German car dealerships. He now acts as a freelance mechanic’s instructor for local schools.