Transmission Converter Clutch (TCC) (2.8L "F" Body)
The purpose of the automatic transmission torque converter clutch feature is to eliminate power loss of the torque converter when the vehicle is in a cruise condition. This allows the convenience of an automatic and the fuel economy of a manual transmission. The heart of the system is a solenoid located inside the transmission, which is controlled by the ECM.
When the solenoid coil is activated, the torque converter clutch is applied, which results in straight through mechanical coupling from the engine to the wheels. When the transmission solenoid is deactivated, the torque converter clutch is released, which allows the torque converter to operate in the conventional manner (fluidic coupling between engine and transmission).
The transmission converter clutch will engage when the following conditions occur:
- Engine is warmed up.
- Vehicle speed is above a calibrated value.
- Throttle position sensor output is not changing, indicating a steady road speed.
- Brake switch is closed.
- This test checks the continuity of the TCC circuit from the fuse to the ALDL connector.
- When the brake pedal is released, the light should come back on and then go off when the diagnostic terminal is grounded. This will test circuit No. 422 and the TCC drive in the ECM.