Upshift Control and Torque Converter Clutch (TCC) Apply
The transmission control module (TCM) calculates the upshift points based primarily on 2 inputs: throttle angle and vehicle speed. When the TCM determines that conditions are met for a shift to occur, the TCM commands the shift by closing or opening the ground circuit for the appropriate solenoid.
Perform the following steps
- Refer to «Shift Speed»(ref-268097-S12514337362007101800000) and choose a throttle position shown to cover the normal driving range.
- Monitor the following scan tool parameters: Throttle angle Vehicle speed Input speed - some models Engine speed Output shaft speed Commanded gear Slip speed Solenoid states
- Place the gear selector in the OVERDRIVE position.
- Accelerate the vehicle using the chosen throttle angle. Hold the throttle steady.
- As the transmission upshifts, note the vehicle speed when the shift occurs for each gear change. There should be a noticeable shift feel or engine speed change within 1-2 seconds of the commanded gear change.
- Compare the shift speeds to the Shift Speed table. Refer to «Shift Speed»(ref-268097-S12514337362007101800000) . Shift speeds may vary slightly due to transmission fluid temperature or hydraulic delays in responding to electronic controls. Note any harsh, soft or delayed shifts or slipping. Note any noise or vibration.
- Repeat steps 1-6 as necessary in order to evaluate the different throttle angles. IMPORTANT: This transmission is equipped with an electronically controlled capacity clutch (ECCC). The pressure plate does not fully lock to the torque converter cover. Instead, the pressure plate maintains a small amount of slippage, about 20 RPM, in SECOND, THIRD and FOURTH gears, depending on the vehicle application. ECCC was developed to reduce the possibility of noise, vibration or chuggle caused by TCC apply. Typical apply speeds are 49-52 km/h (30-32 mph) in THIRD gear and 65-73 km/h (40-45 mph) in FOURTH gear. Full lockup is available at highway speeds on some applications. IMPORTANT: The TCC will not engage until the engine is in closed loop operation and the vehicle speed is as shown in the Shift Speed table. Refer to «Shift Speed»(ref-268097-S12514337362007101800000) . The vehicle must be in a near-cruise condition, not accelerating or coasting, and on a level road surface.
- Check for TCC apply in THIRD and FOURTH gear. Note the TCC apply point. When the TCC applies there should be a noticeable drop in engine speed and a drop in slip speed to below 100 RPM. If the TCC apply can not be detected: Check for DTCs. Refer to «Torque Converter Diagnosis»(ref-268157-S00482585052007101800000) . Refer to the «Shift Speed»(ref-268097-S12514337362007101800000) table for the correct apply speed.
Torque Converter Diagnosis
The torque converter clutch (TCC) is applied by fluid pressure, which is controlled by a pulse width modulation (PWM) solenoid valve. This solenoid valve is located inside of the automatic transmission assembly. The solenoid valve is controlled through a combination of computer controlled switches and sensors.
Torque Converter Stator
The torque converter stator roller clutch can have 2 different malfunctions.
- The stator assembly freewheels in both directions.
- The stator assembly remains locked up at all times.
Torque Converter Clutch Shudder
The key to diagnosing TCC shudder is to note when it happens and under what conditions.
TCC shudder which is caused by the transmission should only occur during the apply or the release of the converter clutch. Shudder should never occur after the TCC plate is fully applied.
Indexing Torque Converter
To determine and correct a torque converter vibration, the following procedure may have to be performed several times to achieve the best possible torque converter to flywheel balance.
Scheme 484
- Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(ref-268088-S13434065972007101800000) .
- Rotate the torque converter one bolt position.
- Align the torque converter hub (2) in the engine crankshaft (3) and install the torque converter to flywheel bolts.
- Lower the vehicle.
- With the engine at idle speed and the transmission in PARK or NEUTRAL, observe the vibration. Refer to «Noise and Vibration Analysis»(ref-268157-S31659101852007101800000) . Repeat this procedure until you obtain the best possible balance.
- Install the transmission converter cover bolts and the cover.
No Torque Converter Clutch Apply (300 RPM Slip)
| Checks | Causes |
|---|---|
| Valve Body Assembly (60) | Regulator apply valve side loading Stuck converter clutch valve Torque converter clutch (TCC) apply valve stuck closed (debris in bore) Torque converter clutch pulse width modulated (TCC PWM) solenoid broken/cracked Turbine shaft O-ring omitted TCC PWM solenoid leaking |
| Input Housing and Turbine Shaft Assembly (621) | Turbine shaft hole not drilled to full depth Scratched turbine shaft journals Turbine shaft O-ring omitted/damaged Turbine shaft retainer and ball assembly restricted or damaged |
| Electrical | 12 volts not supplied to transmission Outside electrical connector damaged Inside electrical connector damaged Wire harness damaged TCC solenoid damaged Electrical short (pinched wire) TCC solenoid not grounded |
| Torque Converter Clutch (1) | Internal damage (blue or distorted) |
| Oil Pump Assembly (4) | TCC spring cocked Orifice cup plug restricted or damaged Pump to case gasket mispositioned Converter clutch valve retaining ring mispositioned Converter clutch valve stuck or assembled backward |
| Transmission Fluid Pressure Manual Valve Position Switch (69) | Contamination Damaged seals |
| Solenoid Screen (367A/367B) | Blocked |
| TCC Solenoid Valve (Part of 66) | Internal damage |
| Engine Speed Sensor | Internal damage |
| Engine Coolant Temperature Sensor | Internal damage |
| Automatic Transmission Fluid Temperature Sensor (Part of 69) | Internal damage |
| Brake Switch | Internal damage |
| TCM | Internal damage |
| TCC PWM Solenoid (Part of 66) | Internal damage |
No Torque Converter Clutch (TCC) Apply
| Checks | Causes |
|---|---|
| Miscellaneous | Low oil presure Engine not tuned properly Contaminated transmission oil |
| Oil Filter (72) | Crack in filter body Flash restricting filter neck O-ring seal (71) cut or damaged |
| Torque Converter Assembly (1) | Internal damage Broken weld or missing weight |
| Oil Pump Assembly (4) | Converter clutch valve (224) stuck Restricted oil passage |
| Input Housing and Shaft Assembly (621) | Turbin shaft O-ring (618) cut or damaged Turbin shaft retainer and ball assembly (617) restricted or damaged |
Torque Converter Clutch Shudder
No Torque Converter Clutch Release
| Checks | Causes |
|---|---|
| TCC Solenoid Valve (Part of 66) | External ground Clogged exhaust orifice |
| Converter (1) | Internal damage |
| Valve Body Assembly (60) | The converter clutch apply valve is stuck in the apply position |
| Oil Pump Assembly (4) | The converter clutch valve is stuck |
| PCM/TCM | External ground |
No TCC Release
Torque Converter Clutch Slip - 100 RPM Slip
| Checks | Causes |
|---|---|
| Valve Body Assembly (60) | TCC/PWM solenoid leaks Regulator apply valve or converter clutch shift valve sticking or side loading |
| Oil Pump Assembly (4) | Stator shaft bushings worn, due to scratched turbine shaft journal (replace bushings and input housing assembly) TCC apply valve is stuck open TCC solenoid leaking |
| Input Housing and Turbine Shaft Assembly (621) | Scratched journal on turbine shaft Turbine shaft O-ring cut Turbine shaft hole not drilled to full depth |
TCC Slip (100 RPM)
Torque Converter Clutch Slip with Stall/Stumble
| Checks | Causes |
|---|---|
| TCC Apply Valve (Part of 66) | Stuck open |
TCC Slip with Stall/Stumble
Torque Converter Clutch Intermittent - OK Cold/Slips Hot
| Checks | Causes |
|---|---|
| TCC PWM Solenoid (396) | Leaks |
| Regulator Apply Valve (216) | Sticking valve |
| Converter Clutch Shift Valve (224) | Sticking valve |
Intermittent TCC OK Cold/Slips Hot