How to troubleshoot a faulty alternator in a Vauxhall Vivaro?

My Vauxhall Vivaro's battery light is constantly on and the vehicle is struggling to start. I suspect that the alternator may be faulty. How can I troubleshoot this issue and potentially fix it myself?

Firstly, check the alternator belt to ensure it is tight and not showing any signs of wear or damage. If the belt is in good condition, then a multimeter can be used to test the output of the alternator. Connect the multimeter to the battery while the engine is running and ensure the voltage is between 13.8-14.4 volts. If the voltage is lower, it may indicate a faulty alternator.

If the alternator is indeed faulty, it is best to replace it with a new one. However, if you are on a budget, you can also opt for a refurbished alternator. When installing the new alternator, make sure to properly tighten all connections and reattach any wiring that was disconnected.

In some cases, an alternator may fail due to an issue with the battery. If the battery is old or corroded, it may not be able to hold a charge and cause strain on the alternator. So, it is recommended to also check the battery's condition and replace if necessary.