Contents: General description ↧ Examination ↧
General description
1. The torque converter clutch (TCC) of an automatic transmission uses a single valve controlled by a solenoid (on 3.1 l engines) or two solenoids (on 3.8 l engines), providing rigid mechanical engagement of the engine flywheel with the output shaft of the gearbox via a torque converter. As a result, by eliminating slippage in the torque converter, engine speed is reduced, and thus the level of harmful emissions. This also results in reduced fuel consumption.
Note: On 1992 vehicles equipped with front and rear air conditioning systems, the TCC system provides locking at speeds of approximately 25 mph (40 km/h). On vehicles equipped with only the front air conditioning system, the TCC system operates at two different speeds. With the air conditioning on, the lockup occurs at 35 mph (56 km/h), and with the air conditioning off, it occurs at 25 mph (40 km/h). These air conditioning systems have different models of compressors.
2. In order for the torque converter clutch to operate normally, two conditions must be met:
- a) The engine must warm up before engaging the clutch. Engine coolant temperature sensor (see section 4) informs the ECM/PCM when the engine has reached normal operating temperature.
- b) In order for the working fluid pressure to rise to the level required to operate the valve, the vehicle must reach the minimum required speed. If the hydraulic pressure reaches the required value, the ECM/PCM supplies the solenoid with (solenoids) signal to engage the torque converter clutch.
3. Once the clutch is engaged, the ECM/PCM uses the information from the TPS sensor to release the clutch when the vehicle accelerates or decelerates to a certain degree of acceleration (slowdowns).
4. The torque converter clutch assembly also uses a brake switch, which, when the brake pedal is pressed, breaks the power supply circuit of the TCC solenoid.
5. On the gearbox of the model ZT40 (3.1L engine) the TCC system uses a 3rd gear switch to signal the ECM which gear the transmission is in. The ECM uses this data to change the conditions under which the clutch will engage and disengage. However, it is not necessary to engage a higher gear for the ECM to engage the clutch. Transmissions that use gear selector switches can be identified by three wires coming out of the TSS electrical connector.
6. On the gearbox model 4T60-E (3.8L engine) clutch solenoids control the amount of fluid that enters the TSS system.
7. In addition, on the 4T60-E model gearbox, a solenoid controlled by blocking the pulse width modulation (PWM) of the signal sent to it is used in the TSS system to change the amount of hydraulic pressure in order to make the TSS system shift more smoothly and with less noise.
Examination
8. When the torque converter clutch is constantly engaged, the engine stalls immediately, just as happens with engines equipped with a manual transmission.
9. If the torque converter clutch is not engaged, fuel economy may be lower than expected. If the vehicle speed sensor (VSS) is faulty (see section 4) the TSS system will not work.
10. A transmission equipped with a TCC system has operating characteristics different from those of an automatic transmission without a TCC system. If there is a popping sound in the muffler or the vehicle moves erratically, perform the following check.
11. Install the tachometer.
12. Warm up the engine while driving to normal operating temperature, maintain the vehicle speed at 50-55 mph.
13. When you press the brake pedal lightly, you should feel a slight kick back, indicating that the TSS system is disengaging. At the same time, the engine speed should increase slightly.
14. When you release the brake pedal, the torque converter clutch will re-engage and the engine speed will drop slightly.
15. If the TSS system is not working satisfactorily, send the vehicle for a system check.
[The original source of the article is the website: CHEVYMAN]