Powertrain Controls - ECM/PCM

DTC 66 3-2 Control Solenoid Circuit Fault:

3-2 Control Solenoid Circuit:

Circuit Description:
Hydraulically, the 3-2 control solenoid coordinates the apply rate of the 2-4 band with hydraulic release, of the 3-4 clutch during a 3-2 downshift.
The PCM continually monitors the 3-2 circuit duty cycle depending on the commanded state of the circuit. When the transmission is in first gear the duty cycle of the solenoid is equal to 0. When the transmission is in second gear or higher the duty cycle of the solenoid will be about 90%. When the transmission downshifts, 3-2, the duty cycle of the solenoid will be about 20%.
For example: If the PCM commands the solenoid "ON," the voltage on that circuit should drop when the solenoid is grounded, if voltage stays up for 4 seconds DTC 66 will set.
If the 3-2 solenoid is "OFF," the duty cycle on the circuit should remain high if the voltage drops for 4 seconds, DTC 66 will set. When DTC 66 is set a soft landing will occur.

Test Description:
Number(s) below refer to circled number(s) on the diagnostic chart.

1. This test checks the 3-2 control solenoid and the internal transmission harness for shorts.
2. This test checks for power to the 3-2 control solenoid from the ignition through the fuse.
3. This test checks CKT 897 for a short to ground.
4. This test checks the PCM ability to ground or control the 3-2 control solenoid.

Diagnostic Aids:
Check all connections at the transmission pass-thru connector.
If OK, refer to "Diagnosis By Symptom." Testing and Inspection
Some slight TCC slip is normal.
The 3-2 control solenoid feedback normally oscillate "ON/OFF" when the duty cycle is applied.