davemax

Today I was driving hear in rainy southern mass and my car just died on me. Before it died the airbag light started to blink and the wipers on the high setting was working really slow. My belts have benn squeaking for a while and was planning to put new ones on this weekend. I think it is my alternator but not sure if it is just loose belts. I jumped the battery to start it again to get it home but the airbag and wipers started up again and I just reved the engine until it went away.

Anybody ever have this propblem? And does this sound like my alternator?

How do I check the alternator to see if it is bad?

Davemax

twiggy144

If you have a voltmeter, you can perform this simple and quick test:
voltage at the posts of a good car battery, engine not running : should be 12.5 V or above. Engine running: between 14.0 and 14.7 V.

One mech gave me a wise tip once. Should batteries last 5 years, replace them at 4 years. He said that would put less stress on the alternator. Batteries are much less expensive to replace than alternators, and incur almost no car " downtime" .

davemax

Just tested the battery witht the car off and got 12.5v and w/ the car running and nothing on (radio, def, lights ect..) got a reading off the battery just below 13 v
Thanks for the tip

twiggy144

Sounds like either the alternator or the voltage regulator. If you can probe the voltage at the alternator itself while the engine is running, you will confirm the diagnostic. Be cafreful tough. Clip your probes first then start the engine. 7 years is normal life for an alternator.

davemax

Worked on my car this past saturday and it ended up being the belt. All the groves were worn out and the rain must have made the belt skip and not charge the system. Now I get a charge of 14.33 volts.
Thanks

twiggy144

The belt of course ! I didn't think about this one. Lucky you: a 20$ repair instead of 300$.