Engine over revs and blinkers don't work (sometimes). Help! Olds Alero.

true24

I took my 4 cyl 2004 Alero to the GM dealer because the turn signals work less and less frequently and to top it off, the battery light comes on and the engine revs up to 4000rpm going a max of 40 mph! When the battery shuts off a minute later, the engine runs normally again. This only happens when the car is cold (after I get off work), but the lights do their own thing when they want. No blinker, no sound. The dealer wants to charge me $1000 for a new alternator and control module, but I just changed the alternator, battery, fuel pump, and had a tune-up. Can anyone help?

Mr_Shiftright

You need a scan tool to reset it---but what does the code read, do you know?

As for the alternator and BCM,, you have to work a deal out with them that if it doesn't fix the problem, or at least SOME of the problem, then they take off the parts and put your old ones back, no charge.

An authorized dealer with trained techs should not have to guess how to fix your car.

Mr_Shiftright

No matter if you just changed it--if the battery light is still on, you have a charging problem, and if the alternator or battery isn't functioning well enough to provide proper voltages to the car's electrical system (hopefully somewhere around 13.8 to 14. 2 V), then your car's modules are going to go nuts.

So back to square one here, and have someone at least put a voltmeter on the battery terminals while you rev the engine, and see what it reads.

true24

Thanks for the response. I had the alternator and battery tested before I took the car to the dealer. They both passed. 

true24

So the dealer tells me that I need a new alternator and a new BCM. I think he is trying to play me about that last thing. From what I have read, it looks like the BCM controls things like the radio, trunk, and passlock security, and I don't have those problems. However, I do have an engine light on that I can't get rid of. Any idea how to reset it?