Chart C-8 Torque Converter Clutch (TCC) Diagnosis

Chart C-8A:

TCC Circuit:

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

TEST DESCRIPTION: Number(s) below refer to circled number(s) on the diagnostic chart.

1. This test should be performed with the aid of a helper, to operate the scan tool 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. 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 about (35 mph with A/C "OFF," 44 mph with A/C "ON").
^ Engine at normal operating temperature above about 20°C (68°F).
^ Throttle Position (TP) sensor output not changing, indicating a steady road speed.
^ Brake switch closed.
^ 3rd gear switch applied.