Torque Converter Clutch: Testing and Inspection

Chart C-8A - Torque Converter Clutch (TCC):

Chart C-8A Wiring Circuit:

Circuit Description:

The purpose of the Torque Converter Clutch (TCC) is to eliminate the power loss of the transmission converter stage when the vehicle is in a cruise condition. This allows the convenience of the automatic transmission and the fuel economy of a manual transaxle.

Fused ignition feed is supplied to the TCC solenoid through the brake switch and transmission TCC in-line switch. The ECM engages TCC by grounding CKT 422 to energize the solenoid.

TCC will engage when the following conditions are met:
^ Engine warmed up.
^ Vehicle speed above a calibrated value (about 33 mph 51 km/h).
^ Throttle position sensor output not changing, indicating a steady road speed.
^ Transmission 3rd gear switch open.
^ Brake switch closed.
^ TCC in-line switch closed.

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

1. Checks ERLS fuse, CKT 439' brake switch.
2. Checks ECM for proper operation.
3. Checks the internal switches in the transaxle.

Diagnostic Aids:

The Tech 1 only indicates when the ECM 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 indicates the TCC driver has turned "ON."

If the ECM, TCC solenoid, and control circuitry are functioning correctly but the TCC still does not apply properly, the problem may be hydraulic or mechanical.