I am no longer looking for a PCM. Here is the total history on my tranny.
I have a 2002 Mazda protege 5, 2L engine, automatic 4 speed trans (4F27E) with 71000 miles. I started with intermittent losing 4th then after awhile it would not go into 4th. When it was time to go into 4th it would just go into neutral. I could shift over to manual (tiptronic) and shift into 3rd to continue to drive. It is hard to tell the difference between 2nd and 3rd. I figured one or more Shift Solenoids were bad so I replaced all 6 of them with no change at all. I tapped into the wires going into the transmission and directly to Shift Solenoids A, C, D, and E and measured when the solenoids were applied voltage. I compared that with a Shift Solenoid Application Chart and mine was correct with one exception - A was supposed to have voltage in reverse and mine did not (can't see that that would make any difference). Solenoid A had 12 volt application voltage and C, D, E had 4 volts. 4 volts was plenty - I made a test on that type solenoid and 2 volts or even less would operate it. At one time I thought the PCM (Powertrain Control Module) was at fault because of the lower voltage on C, D, and E but 4 volts is fine. Besides, these solenoids measure only 3 ohms or less that means if 12 volts were applied it would be drawing 4 amps or more. If anyone has any thoughts on other simply tests I can make before I declare 4th gear (speed or whatever) is totally gone and have to replace transmission. This would be way more than the car is worth.
I thank the person that sent me the link to 2002 Madza Protege 5 shop manuals. There is an error in the Wiring Diagram Supplement on page 22 (B-2C). The shift solenoid are mislabeled: C should be E; A should be C; B should be D; E should be B; and D should be A. This may show up in other pages also (like 01-40B-6). This incorrect info through me off for a while. There may have been a revision to the Shift Solenoid's labeling put out by Mazda but I was not privy to it. Info to the wise.