Electronically Modulated Converter Clutch (EMCC)

Torque Converter Clutch (TCC) operation is controlled by the Transmission Control Module (TCM) through the solenoid and pressure switch assembly and valve body. When the transaxle is in 2nd, 3rd, or 4th gear, the TCC can be energized when certain conditions are met.
In order to reduce heat build-up in the transmission and buffer the powertrain against torsional vibrations, the TCM can duty cycle the L/R-CC Solenoid to achieve a smooth application of the torque converter clutch. This function, referred to as Electronically Modulated Converter Clutch (EMCC) can occur at various times depending on the following variables:
- Shift lever position
- Current gear range
- Transmission fluid temperature
- Engine coolant temperature
- Input speed
- Throttle angle
- Engine speed
The TCM controls the torque converter by way of internal logic software. The programming of the software provides the TCM with fine control over the L/R-CC Solenoid. There are four output logic states that can be applied as follows:
- No EMCC
- Partial EMCC
- Full EMCC
- Gradual-to-no EMCC

NO EMCC
Under No EMCC conditions, the L/R Solenoid is OFF. There are several conditions that can result in NO EMCC operations. No EMCC can be initiated due to a fault in the transaxle or because the TCM does not see the need for EMCC under current driving conditions.

PARTIAL EMCC
Partial EMCC operation modulates the UR Solenoid (duty cycle) to obtain partial torque converter clutch application. Partial EMCC operation is maintained until Full EMCC is called for an actuated. During Partial EMCC some slip does occur. Partial EMCC will usually occur at low speeds, low load and light throttle situations.

FULL EMCC
During Full EMCC operation, the TCM increases the L/R Solenoid duty cycle to full ON after Partial EMCC control brings the engine speed within the desired slip range of transaxle input speed relative to engine rpm.

GRADUAL-TO-NO EMCC
This operation is to soften the change from Full or Partial EMCC to No EMCC. This is done at midthrottle by decreasing the L/R Solenoid duty cycle.