Vauxhall Astra electrical problem (UK)?
I have a 1994 Vauxhall Astra which despite being well past the UK government's 'scrap by' date has only done 73,000 miles and is a clean and normally reliable car.
This morning it developed a fault however. Whenever I go much past 30 mph the alternator warning light starts flickering. More worrying still is the fact that at 45 mph the air bag warning light flashes and stays on steadily at 50 mph.
My first thought was the alternator drive belt but that seems reasonably tight and there is no sign of overheating (the same belt drives the water pump). Any ideas? I have most tools including a voltmeter but no idea of what voltage I should expect from the alternator.
I measured the voltage at the battery. On tickover it's 13.6v. If I rev the engine it rises to 16.5v and the alternator and airbag warning lights come on!