[FIXED] Mazda 2.3L turbo overcharging problem

  2009 Mazda cx7 sport, 2.3L turbo. Output voltage from generator oscillating between 15.5 and 18.5 volts while idling, remains above 18v when rpms rise. Desired voltage output from computer shows 14v on scan tool. Vehicle idles rough when generator connector is plugged in and I get several DTC s showing circuit high, airbag dtc s, and abs dtcs as well.  Unplug 2 wire connector at terminal, runs fine and trouble codes are not active. Replaced alternator and getting same exact issues.  blu and gry wires from field terminals to pcm are good. ( no opens or shorts)  Questioning PCM power, grounds?  Also has a constant clicking coming from what i believe is the swirl shutter valve while the key is on. No Batt light on dash either. The only other thing I can think of is I noticed in my live data streams that it showed low input voltage to the PCM @ 7.4v.  I have a few ideas, but could use some experienced direction before I condemn the PCM.

If these are the same as fords they should go into default charge. Unplug the alternator and rev snap the throttle passed 3000 rpm a few times should default to 13.5 volts.

That input voltage at 7.4V... I'd definitely go over PCM powers and grounds with a test light or substitute load.

What's the voltage reading on the case of the alternator itself during the overcharging?

Will try next opportunity and let you know results.

Was a power issue. ECM fuse 10A was completely missing. Restored and now alt. works great. Now on to the rest of the problems. Thanks for the help

Thanks for the follow up! Great catch with the input voltage in the scan data. This could have got a PCM or three... :lol: