Drain the transmission fluid, take off the transmission pan and filter, and remove the valve body so you can test the transmission solenoids and their contacts. You should find 4 solenoids on the valve body. The torque converter clutch solenoid coil, the pressure control solenoid valve coil, and the shift control solenoid valves A and B coils.
The ohm specifications for the torque converter clutch solenoid coil should be approximately 13 ohms. The pressure control solenoid valve coil should be near 3 ohms, and Shift Control solenoid valves A and B coils should be near 22 ohms. Resistance should be checked while the coils are at 68f. temperature.
Along with checking the transmission solenoids, check the wiring harness between the transmission control module and the solenoids.
