How to tell if the alternator is faulty in a 2009 Holden Cruze

Most mechanics would go back to basics for this one. With the engine running, you place the leads of a volt-meter across the terminals of the battery. This will tell you how much power the alternator is putting into the battery to keep the latter charged. You want to see a figure of up to about 14.5 volts, and anything less than about 13 volts suggests the alternator is struggling.

If you get a low reading, try the test with the engine just off idle as this can sometimes wake the alternator up and get it pulling its weight. Don’t forget to do the test with all the lights ad stereo off, and the air-conditioning switched off, too.