94 Mazda B4000 Shift motor wont shift in 4wd

[Billy The Kidd]

I followed the tech tips from this site on diagnosing shift motor by Chris1044.
Prior to replacing shift motor the SCM (shift control Module)would click and switches would blink on and off.
I replaced shift Motor now no lights no clicking. Ran scm self test and got no lights. Have input voltages. Replaced scm same problem (found the the test switch on scm flacky when i push it really hard on the original scm it passed the self test).
Checked voltages and wiring. Pin 1 on gray 5 pin only has 5.8vdc. pin 2 gets 5.8vdc when 4w Hi is depressed. It should be 12vdc. Also the speed sensor reads 40000 ohms should be 200-500 ohms (Tried bypassing to observe changes nothing)
I do seem to have the proper 12vdc and ground on the scm pigtail. However if i diconnect the pigtail i get 12vdc on pins 1 and 2 of the 5 pin gray connector(had 5.8vdc connected).
BTW just bought this vehicle and there were already 2 scm's in the jump seat.
Seems like bad SCM to me but we have 3 SCMs with same problem not very likely. Unless shift motor shorted out scm. checked wiring for any shorts no go.
I'm baffled.

 

[Spott]

Can you shift the transfer case manually, by taking the motor off and turning it with a pair of pliers? Maybe it's jammed.

Next, I would try exchanging your new shift motor, it may be faulty. (The shift motor includes the sensors, right?) If a replacement behaves the same way, then I would suspect the wiring and connectors between the two.

It helps to backtrack: originally, everything worked except the shift motor. You replaced the shift motor, and more problems arose. The additional problems were likely caused by the replacement shift motor, or the process of replacement.

Of course, other problems are possible, but that's where I would start troubleshooting. Let us know what you find.