OBD code P1633 - Any advice where to start?

My idiot light came on and the code is P1633. Keep alive power voltage too low. The light came on after my A/C compressor froze and snapped my serpentine belt. Not sure if that's related but it was the only problem I've had.
I replaced my A/C compressor and belt and the engine is purring again. Problem is I try to erase the code and it wont go. The CEL light will blink off for a second and come right back on.
I've checked and ruled out the battery and fuses. I don't know much about electrical so I could use some advice on what to try to trace this problem.
The car is a 2001 Taurus Vulcan.

TaurusGLenn

EEEK! According to the service manual, possible causes are:

Open KAPWR circuit
Damaged PCM
Intermittent KAPWR CircuitI don't have time this morning to dig into what all is part of the keep alive power circuit, but it doesn't sound good.

If you'd like to start running through the troubleshooting steps, send me a private message with an e-mail address for you that can accept PDF attachments and I'll send you the procedure.

-Rod

Thanks for the reply Rod. I wrote out a detailed private message and it wouldn't send. AF was having difficulties.
Will try to resend later.

OK did a little more troubleshooting and found that the ground to the PCM was ever-so-slightly corroded. I cleaned and reinstalled. Then I checked the power control fuse box and found a tiny piece of the fuse box plastic had broken off and fell in between the contacts of fuse number 22. Related to my P1633 promblem? I don't know. I pulled that piece of broken plastic out and reinstalled the fuse.
I didn't check in between doing the two troubleshooting jobs so I'm not sure which one was the culprit. But now that scary code is gone and that's what matters most.