DTC 39

Torque Converter Clutch (TCC) Circuit:

Code 39 Diagnostic Chart:

Circuit Description:
The purpose of the Torque Converter Clutch (TCC) feature is to eliminate the power loss of the torque converter when the vehicle is in a cruise condition. This allows the convenience of the automatic and the fuel economy of a manual transaxle. The heart of the system are two PCM controlled solenoids located inside the transaxle.

When the TCC apply solenoid coil is activated ("ON"), the Torque Converter Clutch (TCC) is applied which results in a straight through mechanical coupling from the engine to the wheels. When the apply solenoid coil is deactivated ("OFF"), the Torque Converter Clutch (TCC) is released which allows the torque converter to operate in the conventional manner (fluidic coupling between engine and transaxle).

The TCC PWM solenoid is used to vary hydraulic pressure to the converter clutch regulator valve, allowing a smoother engagement of the converter clutch. Code 39 will set if:

^ TCC is commanded "ON" by the PCM.
^ Vehicle speed is 35 mph or more.
^ Throttle angle is 10% or more.
^ Vehicle is in 3rd or 4th gear.
^ Engine rpm/vehicle speed ratio indicates TCC is not locked.
^ Above conditions for over 10 seconds.

Code 39 does not illuminate the "Service Engine Soon" light.


Diagnostic Aids:
The Tech 1 only indicates when the PCM has commanded the TCC driver "ON"; this does not confirm that the TCC is actually engaged. To determine if TCC is functioning properly, road test the vehicle. Engine rpm should decrease when the Tech 1 indicates the TCC has been turned "ON." If diagnosis indicates that all electrical circuits and components are OK, refer to "Automatic Transaxle Diagnosis," for hydraulic and mechanical diagnosis.