2002 Protege5 2.0L, 99,990 miles.
A few days back the head lights, interior lights all would go dim and get bright in sink with the engine idle surging from 850 RPM up to 1800 RPM. up & down, dim & bright.
I used my DVOM to measure voltage at the Battery: 12.5v up to 17.8v up and down between those readings consistently.
I suspected the Alternator was failing(sometimes called full fielding),
I ordered a replacement alternator from "Maniac Electric Motors"
I Removed & Replaced the Alternator and the Battery.
It was no help. The same problem exists.
I scanned it with my SOLUS-PRO scan tool. Detected a PCM code,
P1632- Generator Voltage to PCM Below 8 volts.
I also read something about checking the wt/gr wire from the Fues Box to
the PCM.
Has any one had this issue before?
Can any one point me in the right direction?
BTW: the issue seems to level out when the heater fan switch is turned on.
I can also hear the A/C Compressor cycling on/off when the Heater Fan Control Switch is turned on.
A wire is "crossed" somewhere!
Where is the PCM located in this car?
Is there a Diagnostic Pin-Point Test available for DTC-P1632?
{I don't have access to ALLDATA from my home computer}

Thanks for any help you guys can offer!!