Torque Converter Clutch: Testing and Inspection

Chart C-8A:

TCC Circuit:

CIRCUIT DESCRIPTION:
The purpose of the Torque Converter Clutch (TCC) 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 transmission and the fuel economy of a manual transmission.

TEST DESCRIPTION: Numbers below refer to circled numbers on the diagnostic chart.

1. This test should be performed with the aid of a helper to operate the Tech 1 and observe the rpm fluctuation.

2. Entering the "Field Service Mode" forces the ECM to close the TCC control driver circuit completing the path for current which should light the test light.

3. Perform this test with the aid of a helper. The 3rd gear switch must be engaged while measuring the TCC solenoid resistance.

DIAGNOSTIC AIDS:
Fused battery ignition is supplied to the TCC solenoid through the brake switch. The ECM will engage TCC by grounding CKT 422 to energize the solenoid. TCC will engage when:

^ Vehicle speed above 35 km/h (22 mph).
^ Engine at normal operating temperature (above 70°C, 158°F).
^ Throttle position sensor output not changing, indicating a steady road speed.
^ Brake switch closed.