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For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 1997 🢒 Catera 🢒 Transmission/Transaxle 🢒 Automatic Transmission - 4L30-E 🢒 Torque Converter Clutch Diagnosis

Perform all electrical testing first and then the hydraulic testing in order to properly diagnose the Torque Converter Clutch (TCC) system.

The TCC applies as a result of fluid pressure by which a solenoid controls inside of the Automatic Transmission assembly. The solenoid energizes by the completion of the electrical circuit through a combination of switches and sensors.

Torque Converter Stator

The torque converter stator roller clutch can have one of two different malfunctions:

    • Stator assembly freewheels in both directions.
    • Stator assembly remains locked up at all times.

Condition A - Poor Acceleration Low Speed

The car tends to have poor acceleration from a standstill. The car may act normal at speeds above 50 to 55 km/h (30 to 35 mph). If a poor acceleration is present, you should first determine if the exhaust system is not blocked, and the transmission is in first (1st) gear when starting out.

If the engine freely accelerates to high RPM in NEUTRAL (N), you can assume that the engine and exhaust systems are normal. Checking for poor performance in Drive and Reverse will help in order to determine if the stator is freewheeling at all times.

Condition B - Poor Acceleration High Speed

The engine RPM and the car speed have limitations at high speeds. Performance when accelerating from a standstill is normal. The engine may over-heat. A visual examination of the converter may reveal a blue color from over-heating.

If you remove the converter, check the stator roller clutch by inserting 2 fingers into the splined inner race of the roller clutch, then try to turn the race in both directions. The inner race should turn freely clockwise, but may not turn or be very difficult to turn counterclockwise.

Noise

You can usually notice the torque converter whine when the vehicle stops and when the transmission is in Drive or Reverse. The noise increases when the engine RPM is increases. The noise stops when the vehicle is moving or when the torque converter clutch applies because both halves of the converter are turning at the same speed.

Perform a stall test in order to ensure that the noise is actually coming from the converter:

  1. Place your foot on brake.
  2. Put the gear selector in Drive.

    3. Notice: Depressing the accelerator for more than 6 seconds could cause damage to the transmission.

  3. Depress the accelerator to approximately 1200 RPM for no more than six seconds.

Important: Do not confuse torque converter noise with a pump whine noise which is usually noticeable in Park, Neutral and all of the other gear ranges. The pump whine will vary with the pressure ranges.

The torque converter noise will increase under this load.

Replace the torque converter under any of the following conditions:

    • External leaks in the hub weld area.
    • Scoring or damage to the converter hub.
    • Damage to the converter pilot.
    • The converter pilot is broke or fits poorly into the crankshaft.
    • Steel particles are present after flushing the cooler and cooler lines.
    • Damage to the pump
    • Steel particles inside of the converter.
    • The vehicle has the TCC shudder and/or not the TCC apply. Replace the torque converter only after all of the hydraulic and the electrical diagnoses have been made. (the converter clutch material may be glazed.)
    • The converter has an imbalance which cannot be corrected. Refer to Converter Vibration Test Procedure.
    • The engine coolant has contaminated the converter with the antifreeze
    • Internal failure of the stator roller clutch.
    • Excess end play
    • Any heavy clutch debris which is caused by overheating (blue converter).
    • Any steel particles or any clutch lining material that is present in the fluid filter or on the magnet when wear or damage is not present in the internal parts in the unit.his indicates that the lining material came from the converter.

The Torque Converter Should Not Be Replaced If the Following Conditions Exist
    • The oil has an odor, changed color, and there is no evidence of metal or a clutch facing particles.
    • Damage to the threads in one or more of the converter bolt holes.
        Correct with a thread insert. Refer to Engine Mechanical .
    •  Transmission failure did not display evidence of damage or worn internal parts, steel particles or clutch plate lining material in the unit and inside of the fluid filter.
    •  The vehicle has been exposed to high mileage (only). The exception may be where the torque converter clutch damper plate lining has seen excessive wear by any vehicles that operate in heavy and/or constant traffic, such as taxi, delivery or police use.

TCC Shudder

The key to diagnosing the Torque Converter Clutch (TCC) shudder is to note when the shudder happens and under what conditions.

The TCC Shudder should only occur during the Apply and/or Release of the converter clutch, seldom after you fully apply the TCC.

While TCC Is Applying Or Releasing:

If the shudder occurs while the TCC is applying, the problem can be within the transmission or the torque converter. Something is not allowing the clutch to become fully engaged, not allowing the clutch to release, or is trying to release and apply the clutch at the same time. These conditions could be caused by leaking turbine shaft seals, a restricted release orifice, a distorted clutch or housing surface due to long converter bolts, or defective friction material on the TCC plate.

Shudder Occurs After TCC Has Applied:

In this case, most of the time there is nothing wrong with the transmission. As mentioned above, once you apply the TCC, slippage is very unlikely. You may not notice any engine problems under light throttle and load, but these engine problems could become noticeable after the TCC apply when going up a hill or accelerating. This is caused by the mechanical coupling between the engine and the transmission.

Remember: Once you apply the TCC, there is no torque converter (fluid coupling) assistance. Any engine or driveline vibrations could become unnoticeable before the TCC engagement.

Inspect the following components in order to avoid a misdiagnosis of the TCC Shudder and possibly a transmission disassembly or an unnecessary torque converter replacement:

    • Spark plugs -- Inspect the spark plugs for any cracks, a high resistance or a broken insulator.
    • Plug wires -- Look in each end of each plug wire. If there is a red dust (ozone) or a black substance (carbon) present in any of the plug wires, this indicates that the wires are bad. Also, look for a white discoloration of the wire indicating an arcing during a hard acceleration.
    • The distributor cap and the rotor -- Look for breakage or an uncrimping in these components.
    • The coil -- Look for black on the bottom indicating that there is an arcing while the engine is misfiring.
    • The fuel injector -- Check the filter for any plugging.
    • The vacuum leak -- The engine will not receive the correct amount of fuel. The engine may run rich or lean depending on where the leak is.
    • MAP/MAF sensor -- Similar to a vacuum leak, the engine will not receive the correct amount of fuel for a proper engine operation.
    • A carbon buildup on the intake valves -- Carbon restricts a proper flow or air/fuel mixture into the cylinders.
    • A flat cam -- The valves will not open enough in order to allow a proper air/fuel mixture into cylinders.
    • The oxygen sensor -- The is component may command the engine to run too rich or too lean for too long.
    • Low fuel pressure.
    • The engine mounts. A vibration of the mounts can be multiplied by the TCC engagement.
    • The axle joints -- Check the joints for a vibration.
    • The TPS. The TCC apply and release depends on the TPS in many engines. If the TPS is out of specification, the TCC may not release at the right time during initial engine crowd.
    • The Cylinder balance -- Bad piston rings or poorly sealing valves can cause low power in a cylinder.
    • A fuel contamination -- Fuel contamination causes a poor engine performance.

Flexplate/Torque Converter Vibration Test Procedure
  1. Start the engine.
  2. Observe the vibration with the engine at idle speed and with the transmission in Park (P) or Neutral (N).
  3. Turn off the ignition.
  4. Remove the flexplate shield attaching bolts.
  5. Remove the shield.
  6. Remove the flexplate to the torque converter attaching bolts.
  7. Rotate the torque converter 120 degrees (1/3 turn).
  8. Install and tighten the flexplate to torque converter attaching bolts. Tighten the bolts to 62 N·m (46 lb ft).
  9. Reinstall the flexplate shield and install and tighten the attaching bolts.
  10. Start the engine.
  11. Recheck the engine for a vibration. Repeat the procedure until the best possible balance is obtained.