I’ve been fighting my 644G (90s series) I checked the solenoids with an ohm meter found two that were not the same so I replaced them. Still nothing I replaced the TCM and then it worked. I drove it around for 5 minutes came to a hill manually dropped it from 3rd to second gear then it dropped into neutral and I’ve got the same problem. No shifting. I didn’t some investigation online and found a picture of some tests that should be done. The attached picture is what I’ve been following. I got to the 17-27 pins and I find 4.5 volts in all 4 gears. But I’m having trouble finding the magnetic pickup. Supposedly there’s on on the engine block but it’s not there on my machine. Is there a speed sensor on the transmission? Is this just a red herring and the problem is something else?
The magnetic pickup in question is a speed sensor on the transmission output shaft. It should be on the left side of the transmission near the bottom??