Chart C-8A, Torque Converter Clutch Electrical Diagnosis 2.5L TBI W Body

Fig 1: Chart C-8A, TCC Circuit (2.5L W Bodies)

Courtesy of GENERAL MOTORS CORP.

Voltage is supplied to TCC solenoid through brake switch. ECM will engage TCC by grounding circuit No. 422 to energize solenoid.

TCC will engage when:

• Vehicle speed is above 22 MPH.
• Engine is at normal operating temperature.
• Throttle position not changing, indicating a steady speed.
• Brake switch is closed.
  NOTE: Test numbers refer to test numbers in diagnostic chart.
  1. This test should be performed on a level road with the aid of a helper to operate scan tool and observe RPM fluctuation.
  2. Entering Field Service Mode forces ECM to close TCC control driver circuit completing path for current which should light test light.
  3. Perform this test with aid of a helper. the 3rd gear switch must be engaged while measuring TCC solenoid resistance.

Fig 2: Chart C-8A, TCC Troubleshooting Chart (2.5L TBI W Body)

Courtesy of GENERAL MOTORS CORP.