Chart C-8A, 3T40 Torque Converter Clutch Electrical Diagnosis - 3.1L PFI W Body: Notes

Fig 1: Clutch C-8B, TCC Circuit Diagram (3.1L W Body)

Courtesy of GENERAL MOTORS CORP.

When solenoid coil is activated. TCC is applied which results in a straight through mechanical coupling from engine to wheels. When solenoid coil is deactivated, TCC is released which allows torque converter to operate in conventional manner. TCC will engage on a warm engine under given road load in 2nd and 3rd gear. TCC will engage under the following conditions:

• Brake switch is closed.
• Coolant temperature is greater than 149°F (65°C).
• Vehicle speed above a calibrator value about 28 MPH.
• Throttle position not changing, indicating a steady speed.
  NOTE: Test numbers refer to test numbers on diagnostic chart.
  1. This test checks functional operation of TCC circuit.
  2. This test checks TCC control driver in ECM.
  3. This test will confirm there is voltage to terminal "A".
  4. This test confirms ECM has ability to turn TCC on.