Part 1 of 2

Chart C-8C Part 1 Of 2:

Torque Converter Clutch:

Circuit Description:
The purpose of the automatic transaxle torque converter clutch feature is to eliminate the power loss of the torque converter when the vehicle is in a cruise condition. This allows the convenience of the automatic transaxle and the fuel economy of a manual transaxle. The heart of the system is a solenoid located inside the automatic transaxle which is controlled by the PCM.

When the solenoid coil is activated ("ON"), the Torque Converter Clutch (TCC) is applied which results in straight through mechanical coupling from the engine to transaxle. When the transaxle solenoid is deactivated, the TCC is released, which allows the torque converter to operate in the conventional manner (fluidic coupling between engine and transaxle).

The TCC will engage on a warm engine under given road load in 2nd and 3rd gears.

TCC will engage when:

^ Brake switch closed.
^ Engine coolant temperature is greater than 65°C (149°F).
^ Engine "Closed loop" condition
^ Vehicle speed above a calibrated value (about 28 mph 45 km/h).
^ Throttle position not changing, indicating a steady speed.

Chart Test Description: Number(s) below refer to circled number(s) on the diagnostic chart.

1. This test checks the functional operation of the TCC circuit.
2. This test checks the TCC control driver in the PCM.
3. This test will confirm that there is battery voltage to terminal "A".
4. This test confirms that the PCM has the ability to turn the TCC "ON."

Diagnostic Aids: A Tech 1 scan tool only indicates when the PCM has turned "ON" the TCC driver, and this does not confirm that the TCC has engaged. To determine if TCC is functioning properly, engine RPM should decrease when the Tech 1 scan tool indicates the TCC driver has turned "ON" during a road test. A thermostat that is stuck open or opens at too low a temperature may result in an inoperative TCC.