How to Diagnose a Faulty Alternator

August 21, 2022 lucille

It’s a simple fact that if your alternator stops working, your car will stop too, that’s why it’s important to keep your eye on this essential engine part so that you don’t find yourself stranded. There is no doubt that a regular car service might be able to pinpoint a pending problem but in between times it’s handy to know a few things to look out for.

Alternators are used to handle the varying electrical loads that are placed on the engine during operation, and to restore the charge to the battery when you need to restart it. If the battery is overburdened and begins to lose charge it can place stress on the alternator and this is what eventually causes alternator failure.

Finally, when the engine fails to turn over on ignition it is easy to blame the battery, but sometimes alternator failure can be the cause and you need to have it examined by a qualified mechanic. If you try to diagnose the problem yourself by replacing the battery you may be able to get the car to start again but if the alternator has failed you are likely to have the same problem about 20 km down the road.

Whilst most alternators will last for about 120,000 km, there can be some tell-tale signs you should look out for.

If you have an alternator light in your dashboard, it should light up every time you start the engine. If it doesn’t, you may have a problem.

An incorrectly adjusted drive belt can prevent the alternator from supplying sufficient charge to the battery causing the battery to fail. An early indicator of imminent failure will be a loss of power when you turn on the headlights or air-conditioning. Your mechanic will be able to test the belt for cracks or fraying to remedy this problem.

If you have a voltmeter you can check your battery voltage and terminal connections when the engine is running. You should get a reading of between 13.8 V and 15 V, anything lower than that could be an indication of imminent alternator malfunction.

Seasoned motorists or those with a keen interest in engines may be able to detect a grinding noise coming from the alternator, another warning sign indicating a trip to your mechanic.

There can be many other variables in play when it comes to electrical problems in your vehicle and it is not always a safe option to rely upon your previous knowledge. Engine technology is becoming more complex with every new model release and engine electrics are being constantly updated.

The best advice is to leave everything in the hands of car care professional. Sometimes, taking matters into your own hands can result in more expensive damage to your vehicle, especially when it comes to electrical systems. Sensitive computer circuitry play a large part in fault detection and it is a simple matter of hooking up a vehicle’s engine to a diagnostic machine to get the most accurate answer.

By all means be on the lookout for early signs of problems but leave it to your mechanic for the final assessment.