Unfortunately a multimeter will not show any voltage spikes that the alternator is putting out, as multimeters average out voltage to give you a fairly stable number. It takes a scope to see spikes, which can and will do lots of electrical damage to lights, the PCM, etc.
While technically correct, the basics of the statement tend to not work that way.
Sure, you can get a micro duration spike that the sample rate of the meter misses.. but remember.. that huge thing in the circuit. oh yeah.. the LOAD and the storage battery.
Both those serve to physically averave out incoming voltage that is not steady state.
Look at half wave rectifier chargers. constant bump as you get only 1 positive half of a wave form.
Lotsa cheap bat chargers are half wave, and yet they still manage to charge a battery up.
Any spike thrown off by an alt that is going to hurt auto electronics will also be picked up by a meter.
Look at your alternator capacity. As the voltage it puts out goes up past the battery charge voltage, that battery becomes a SUBSTANTIAL load.
If a meter is showing voltage in the 14v range, I'd move my focus to poor connections.
if this is a GM ( i think I read it was ), look real hard at the back of those headlamp clusters... some pretty pathetic design went into the multi part connectors, and they scrimped on the wire size too. Just barley big enough, and just barely works are the two main tech's that went into that design!
