Can anyone tell me how the alt is controlled on my 04 Silverado? When I changed the alt this summer I noticed that it is not voltage referenced (or does not seem to be) like older cars are. I expected to see a voltage signal wire going to the battery (or some other such place) but instead there is a (from what I understand) a wire coming from the computer. Info? I'm noticing that the running voltage is somewhere around 13.5 vs. the 14.X I would expect to see. Ideas?

 

From what I've read, the PCM actually commands the alternator to duty cycle...not sure of the frequency or what the parameters are to make it cycle though

 

crap-o.....I would like to figure out how to adjust the output to be more stable (ie: run 14.2Volts all the time vs. anywhere from 15.X to 13.2 that it does now)....