Upshift Control and Torque Converter Clutch (TCC) Apply
The TCM calculates the upshift points based primarily on 2 inputs: throttle position and vehicle speed. When the TCM determines that conditions are met for a shift to occur, the TCM commands the shift by varying current to the appropriate transmission control solenoids to control oncoming and offgoing clutch pressures.
Perform the following steps:
- Monitor the following scan tool parameters:
- Calc. Throttle Position
- Vehicle Speed
- Engine Speed
- Transmission ISS
- Transmission OSS
- Commanded Gear
- Transmission Control Solenoid Valve 1-9
- TCC Slip Speed
- Place the gear selector in the DRIVE position.
- Accelerate the vehicle using a steady throttle position between 15 and 20 percent. Hold the throttle steady.
- As the transmission upshifts, there should be a noticeable shift feel or engine speed change within 1 to 2 seconds of the commanded gear change. The transmission control solenoid valve pressure command should change to "ON" for the oncoming clutch and "OFF" for the offgoing clutch.
- Note any harsh, soft or delayed shifts or slipping. Note any noise or vibration.
- The TCC feel may not be noticeable. In many applications the TCC will apply after the 1-2 shift and TCC events will not be easily detected using engine speed.
- Monitor Transmission Control Solenoid Valve 7 current while driving and check TCC slip speed when the pressure command indicates that the TCC is commanded to apply:
When the TCC applies, slip speed should be controlled to below 100 RPM when the transmission is not shifting and the throttle is held steady. If the TCC slip exceeds this value for more than 6 seconds after the Transmission Control Solenoid Valve 7 current indicates that the TCC is commanded on:
- Check for DTCs.
- Refer to Torque Converter Diagnosis .
This transmission is equipped with an electronically controlled capacity clutch (ECCC), which allows operation of the clutch without fully locking to the torque converter cover. The clutch maintains a small amount of slippage, approximately 0-50 RPM, depending on the vehicle application. TCC may apply in 1st through 8th gear. ECCC was developed to reduce the possibility of noise, vibration or chuggle caused by TCC apply. Full lockup is available at highway speeds on some applications.