Started getting this message. I'm assuming my alternator is on it's way out. I checked voltage when the car was running and it wasn't much over 12V. The alternator is making some power though because I can disconnect the battery and it will still run. Just wondering if you guys know of anything else I should check before throwing a new alternator on there.

 

Getting your battery checked first is your best bet, but if it's not holding 14 volts when running then your alternator is likely the issue.

 

^ what he said, after the battery has been ruled out it's likely the alternator

 

If it's 12V while running it's 99% chance the voltage regulator on the alternator is bad

 

Are these something that get weak before they go completely bad or are they just on/off? The warning message on my dash seems to be intermittent. Came on this morning on the way to work but didn't come on when I drove home for lunch. Could spinning it fast cause a weak voltage regulator to give out sooner? Just wondering now that I have overdrive pulley and was revving it out to 7,500 rpm when it first happened.

I bought my alternator used. (once again used parts biting me in the ass) Seller said it had ~40k miles on it but it was probably 140k. I had the parts store in town order me in a replacement unit. Going to drop by after work and have them test my battery. I think it is fine but just to rule it out. If the battery is fine I will probably just throw in a new alternator before I drive to an autocross event this weekend 2 hours away.

 

No clue how they fail, I'm sure it could do anything like that. I just know its job is to make sure it's always outputting ~14V. 12V will not charge the battery sufficiently.

 

Went by parts store and had them check my battery. Volts are fine but the amps are low. Also, my car didn't throw up the message at all today so hopefully a new battery will do it.

 

Well I replaced my battery and although it was weak, it is not the problem. Now if I disconnect the battery the alternator doesn't even make enough voltage to keep it running. Looks like I will be swapping alternators tonight.

 

That is one of the worse things you can subject a computer controlled car to. Since the 80's you never try to run a car with the battery disconnected. Some Chrysler alternators will run into the 60 volt range without the battery.

 

I did it for less than a second just to see if I had power. It's going to be fine.

 

You were lucky it was the alternator.

 

I unplugged it when the alternator was putting out power as well and it ran/ didn't explode. I don't see how I'm lucky it's the alternator would have been much easier to just replace the battery. Taking off the TVS sucks.

 

The alternator doesn't explode... The overvoltage can take out any processor without overvoltage protection. I used to demo this in GM courses and we could pop light bulbs.

 

Nah I meant my ECU didn't explode. I have a spare if it does. Plus I knew the voltage wasn't much over 12 before I disconnected battery briefly. Personally I think it is a shitty design if their aren't fail-safes for situations where the battery could become disconnected.

 

New alternator fixed it.