It is possible bench test don't tell if it is overcharging and yes, you are correct about the PCM controlling the charging. Apart from the alternator, the PCM can also possibly cause charging faults.
One way of finding out is to replace with a known good alternator and test. A no charging problem is not too bad but an overcharging system is very dangerous as it can take out a lot of electrical components when voltages spikes.
I once had an older model vehicle which had every bulb in the vehicle blown and wasted a lot of time diagnosing as I did not think of all bulbs blowing when lightings did not work.
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Wednesday, August 22nd, 2012 AT 4:39 AM