Upshift Control and Torque Converter Clutch (TCC) Apply
The PCM calculates the upshift points based primarily on two inputs: throttle angle and vehicle speed. When the PCM determines that conditions are met for a shift to occur, the PCM commands the shift by closing or opening the ground circuit for the appropriate solenoid.
Perform the following steps
- Refer to «Shift Speed»(ref-184171-S38811544942005082200000) and choose a throttle position of 10 percent, 25 percent or 50 percent. All throttle angles shown should be tested to cover the normal driving range.
- Monitor the following scan tool parameters: Throttle angle Vehicle speed 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-184171-S38811544942005082200000) . 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 to complete all throttle angles.
- Check for TCC apply in THIRD and FOURTH gear. Typical apply speeds in FOURTH gear range from 72-88 km/h (45-55 mph) depending on engine size, engine type and axle ratio. 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 Procedure»(ref-184198-S19810508222005082200000) . Lightly tap and release the brake pedal. The TCC will release.
Torque Converter Diagnosis Procedure
The torque converter clutch (TCC) is applied by fluid pressure, which is controlled by a 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 two 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.
If the shudder occurs while the TCC is applying, the problem can be within the transmission or the torque converter. Something is causing one of the following conditions to occur
- Something is not allowing the clutch to become fully engaged.
- Something is not allowing the clutch to release.
- The clutch is releasing and applying at the same time.
One of the following conditions may be causing the condition to occur
- Leaking turbine shaft seals
- A restricted release orifice
- A distorted clutch or housing surface due to long converter bolts
- Defective friction material on the TCC plate
Torque Converter Evaluation and Diagnosis
Replace the torque converter if any of the following conditions exist
- External leaks appear in the hub weld area.
- The converter hub is scored or damaged.
- The converter pilot is broken, damaged, or fits poorly into the crankshaft.
- You discover steel particles after flushing the cooler and the cooler lines.
- The pump is damaged, or you discover steel particles in the converter.
- The vehicle has TCC shudder and/or no TCC apply. Replace the torque converter only after all hydraulic and electrical diagnoses have been made. The converter clutch material may be glazed.
- The converter has an imbalance which cannot be corrected. Refer to «Flexplate/Torque Converter Vibration Test»(ref-184198-S25740555592005082200000) .
- The converter is contaminated with engine coolant which contains antifreeze.
- An internal failure occurs in the stator roller clutch.
- You notice excessive end play.
- Overheating produces heavy debris in the clutch.
- You discover steel particles or clutch lining material in the fluid filter or on the magnet, when no internal parts in the unit are worn or damaged. This condition indicates that lining material came from the converter.
Do not replace the torque converter if you discover any of the following symptoms
- The oil has an odor or the oil is discolored, even though metal or clutch facing particles are not present.
- The threads in one or more of the converter bolt holds are damaged. Correct the condition with a new thread insert.
- Transmission failure did not display evidence of damaged or worn internal parts, steel particles or clutch plate lining material in the unit and inside the fluid filter.
- The vehicle has been exposed to high mileage only. An exception may exist where the lining of the torque converter clutch dampener plate has seen excess wear by vehicles operated in heavy and/or constant traffic, such as taxi, delivery, or police use.
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.
- Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(ref-184175-S17163319502005082200000) in General Information.
- 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-184197-S29245845702005082200000) . Repeat this procedure until you obtain the best possible balance.
- Install the transmission converter cover bolts and the cover.
No Torque in Reverse and Third
| Checks | Cause |
|---|---|
| Forward Clutch Hub (613) | The hub is broken. |
| Snap Ring (616a) | The ring is not seated. |
| Forward Clutch Housing (602) | The housing is broken. |
| Direct Clutch Piston (619) | The piston is broken. |
No Torque in Reverse and Third
No Torque Converter Clutch (TCC) Apply
| Checks | Cause |
|---|---|
| TCC Shift Solenoid Valve (323) | Stuck Off O-ring failed No voltage to the solenoid Poor connection |
| PCM | Failed No signal to the solenoid |
| Brake Switch | The contact is corroded. Poor connection Pinched wire Misadjusted No supply voltage |
| TCC Valve (223) | The valve is stuck Off due to sediment or to an undersized bore. |
| Retainer Pin (211) | Broken |
| Torque Converter (1) | Ballooning |
| Turbine Shaft (502) | Plugged oil holes |
| Turbine Shaft Seals (501) | Ineffective |
| Pump Body Bushing (202) | Worn |
| O-ring (2) | Heat set |
| Oil Transfer Hole Cup Plug | Leaking |
| Regulated Apply Valve (324) | Stuck |
| TCC Valve Release Exhaust Orificed Cup Plug | Blocked |
| Check PCM for the current DTCs. | |
| Refer to Incorrect Torque Converter Clutch (TCC) Apply or Release . | |
No Torque Converter Clutch (TCC) Apply
Soft Torque Converter Clutch (TCC) Apply
| Checks | Cause |
|---|---|
| Turbine Shaft Seals (501) | Ineffective |
| Pump Body Bushing (202) | Worn |
| O-ring (2) | Heat set |
| Oil Transfer Hole Cup Plug | Leaking |
| TCC Solenoid (323) | Malfunction |
| Fluid | Low pressure |
Soft Torque Converter Clutch (TCC) Apply
Torque Converter Clutch (TCC) Slipping
| Checks | Cause |
|---|---|
| TCC Valve Release Exhaust Orificed Cup Plug | Blocked |
| Turbine Shaft Seal | Cut |
Torque Converter Clutch (TCC) Slipping
Torque Converter Clutch (TCC) Stuck On
| Checks | Cause |
|---|---|
| Gasket (6) | Damaged |
| TCC Shift Solenoid Valve (323) | Stuck On Pinched wire to ground |
| TCC Apply Valve (324) | Stuck |
| PCM | Failed |
| Check PCM for current DTCs | |
| Refer to Incorrect Torque Converter Clutch (TCC) Apply or Release . | |
Torque Converter Clutch (TCC) Stuck On
Incorrect Torque Converter Clutch (TCC) Apply or Release
| Checks | Cause |
|---|---|
| AT Output Shaft Speed Sensor Assembly (22) | Poor connection Pinched wire A broken coil wire Incorrect air gap Inadequate signal |
| Throttle Position Sensor | Poor connection Pinched wire Incorrect resistance |
| PCM | Failed |
| Automatic Transmission Fluid Pressure Manual Valve Position Switch (40) | Poor connection No signal to the PCM Pinched wire |
| AT Fluid Temperature Sensor Assembly (332) | Poor connection No signal to the PCM Incorrect resistance Pinched wire |
| Engine Coolant | No signal to the PCM |
| Brake Switch | Poor connection Pinched wire No voltage supply Misadjusted |
| Engine Ignition Module | Loss of signal or intermittent |
| Check the PCM for current DTCs. | |
| Only 2WD | |
Incorrect Torque Converter Clutch (TCC) Apply or Release
No Torque Multiplication
| Checks | Cause |
|---|---|
| Stator Shaft (235) | Broken or detached from the pump cover |
No Torque Multiplication
No Torque in Second Gear
| Checks | Cause |
|---|---|
| Intermediate Sprag (624) | Worn Excessive eccentricity The sprag is rolled over or the sprag is damaged. |
No Torque in Second Gear