alternator light on, 930

[MVZ944T]

If the alternator light on the dash stays on, and the car starts, is the alternator malfunctioning, or could it be a fuse or relay. Car started fine last weekend but the light stayed on. I shut the engine off and it would not restart. I recharged the battery and it starts fine, but the light still stays on.

Any suggestions as to where to start looking?

[Jad]

I am certainly not a 930 expert, but generally the alternator light means the alternator is not producing voltage. The car will run on the battery for awhile as you described, but the battery will lose its charge, also as you described. Recharging the battery will buy you a bit more running, but will go dead again. Seems like a clear case of a dead alternator to me with my experience on other cars.

[Mike]

Mike that light can indicate a broken fan belt, no cooling fan.
Sounds like the belt is fine and as Jad mentioned you have a charging issue.

[Steve Grosekemper]

Mike,

If the light is on, the charging system is not working.
No question about it. No fuses or relay's involved.

The blue wire at the bulb goes directly to the back of the alternator making a detour at the voltage regulator. So if it is on you don't have a broken wire in the D+ circuit.

You can have a bad voltage regulator, a bad alternator, broken wiring at the back of the alternator (Black/brown/red) or at the starter solenoid (large red).

If you need to remove the alternator be sure to check the housing as they like to crack at the three legs. Also add a better ground from the alternator to the engine case.

[MVZ944T]

Thanks guys. Last night I was able to find some information on the PCA tech site. One of the things that can happen, and in this case I suspect it might be, is the diodes in the voltage regulator can burn out. One of the things that can cause this is to impart to rapid a charge on the battery. I may have accidentaly done that trying to see if the battery would take a charge. I should have know better and disconnected the leads prior to charging, which I did not.

So Steve, question #2. Can one remove the alternator without dropping the engine. Seems like a few years ago I was trying to the fan out to powder coat it and as I recall, there was not adequate room to remove it. Hopefully I am wrong about that.

Thanks,

Mike