you can check for codes on the transmission,
turn the ignition on but dont start the engine press in the overdrive button so the light goes off on your dash -
install jumper wire in to terminals TE1 and E1 then watch the overdrive light flash the codes.
codes are
42 = speed sensor circuit,
46 = No 4 solenoid sensor circuit,
61 = No 2 speed sensor circuit,
62 = No 1 solenoid sensor circuit,
63 = No 2 solenoid sensor circuit,
64 = N0 3 solenoid sensor circuit,
67 = OD direct clutch speed sensor circuit,
68 = kickdown switch circuit..
to clear the codes turn the ignition off remove ECT ECU fuse for 10 seconds ( switch ignition on ensure overdrive light is off indicates system is normal ).
fuse for ECT ECU is in junction box 2 left front corner engine compartment