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

Automatic transmission torque converter clutch eliminates the power loss of torque converter when vehicle is in a cruise condition. Fused battery voltage is supplied to TCC solenoid through the brake switch and transmission third gear apply switch. ECM will engage TCC by grounding circuit No. 422 to energize the solenoid. TCC will engage when:

• Vehicle speed is between 26 and 40 MPH.
• Engine at normal operating temperature (greater than 156°F, 70°C).
• Throttle position sensor output not changing, indicating a steady road speed.
  NOTE: Test numbers refer to test numbers on diagnostic chart.

1. Light off confirms transmission third gear apply switch is open. This switch should be open for this test.
2. At 30 MPH, the transmission third gear apply switch should close. Test light will come on to confirm voltage supply and a closed brake switch.
3. With engine off, grounding diagnostic terminal should energize TCC solenoid. This test checks capability of ECM to control solenoid. Check TCC solenoid resistance as follows:

• Disconnect TCC at transmission.
• Connect ohmmeter between transmission connector, opposite harness connector terminals "A" and "D".
• Raise drive wheels.
• Operate engine, in Drive, at about 30 MPH to close 3rd gear apply switch.
• If resistance is less than 20 ohms with switch closed, replace TCC solenoid.