Adding diodes to alternator excite wire?

Is it possible to trick the PCM into telling the alternator it needs more voltage? I've seen this done with diodes on other vehicles. Has anyone had any luck with this?
 
No idea which vehicle year you're asking about, but charging these days is generally done via smart systems, which have no external excite wire. Probably the only people who could 'trick' a smart system are the ones who wrote or tested the computer code. What's the reason you need to have more voltage?
 
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I'm trying to avoid buying a HO alternator I installed a full car stereo system and the subs and capacitor are pulling a lot of voltage (06" Mazda5)
 
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Your '06 may very well have an older, non-smart charging system - IDK because I don't have access to a wiring diagram. However, even if it does, and you could trick it into producing max voltage, doing so would probably trash the alternator fairly short order. Alts are not intended to run at max output continuously, so you would be much better served by buying the HO which will run somewhere in the middle of its curve. But as always, your vehicle, your choice.
 
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