Torque Converter Clutch
The torque converter clutch (TCC) is applied by fluid pressure, which is controlled by a TCC pressure control solenoid. This solenoid is part of the control solenoid valve assembly, which is located inside the automatic transmission assembly. The solenoid is controlled through a combination of computer controlled switches and sensors. Electronically controlled capacity clutch (ECCC) is controlled slip across the TCC.
Torque Converter Clutch Shudder
The key to diagnosing torque converter clutch (TCC) shudder is to note specific conditions including AFM/cylinder deactivation. TCC shudder should only occur during the apply, release, or ECCC conditions of the converter clutch. Shudder will never occur after the TCC is fully locked, approximately 0 RPM slip.
Shudder occurs during TCC apply, release, or ECCC
If the shudder occurs while the TCC is applying, the problem can be within the transmission or the torque converter. The TCC may not be engaging, releasing or controlling slip as commanded.
One of the following conditions may be causing the TCC Shudder to occur:
- Degraded transmission fluid - degraded shift quality may also be present
- Leaking turbine shaft/TCC seals
- A restricted release orifice
- A distorted clutch or converter cover due to long flexplate to converter bolts
Perform TCC slip control test within this procedure. Compare service tool collected data results to normal, degraded and damaged operation.
| TCC SLIP CONTROL TEST RESULT | TCC RPM Slip Peak to Peak, at Steady Throttle | ACTION | NOTE |
|---|---|---|---|
| Figure 2: Normal | Below 20 RPM | Do nothing | - |
| Figure 3: Degraded | Near 60 RPM - repeating | Replace transmission fluid | Shudder, surge, fish bite likely |
| Figure 4: Damaged | Near 100 RPM- erratic | Inspect transmission further | Inspect transmission pan magnet for excessive metal accumulation |
Vibration occurs after TCC has locked
TCC enabled with service tool will allow zero slip speed and provide significant vibration that is typically isolated with calibration controlled TCC slip.
Engine problems may go unnoticed under light throttle and load, but they become noticeable after the TCC has locked when going up a hill or accelerating. In order to avoid misdiagnosis of TCC shudder and the unnecessary disassembly of a transmission or the unnecessary replacement of a torque converter, refer to Symptoms - Engine Controls.