Circuit/System Testing

1. Drive the vehicle in D4 until the transmission shifts into 4th gear and the TCC is commanded ON. Observe the TCC Release Pressure parameter on the scan tool. The TCC Release Pressure should display No.
   • If the TCC Release Pressure displays Yes, turn OFF the engine and disconnect the automatic transmission 20-way inline connector. Using the J 35616  GM terminal test kit, jumper the TCC release switch circuit at the engine harness side to ground. Turn ON the ignition with the engine OFF. If the TCC Release switch parameter displays Yes, test the TCC release switch circuit for an open between the TCM and the automatic transmission 20-way inline connector. If the parameter displays NO, test the TCC release switch signal circuit for an open between the automatic transmission 20-way inline connector and the TFP manual valve position switch.
2. Connect the automatic transmission 20-way inline connector. Start the engine and observe the TCC Release Pressure parameter on the scan tool. The TCC Release Pressure should indicate Yes.
   • If the TCC Release Pressure displays No, disconnect the automatic transmission 20-way inline connector.
3. With the automatic transmission 20-way inline connector disconnected, observe the TCC Release Pressure parameter on the scan tool. The parameter should display Yes.
   • If the parameter displays Yes, test the TCC release switch signal circuit for a short to ground between the automatic transmission 20-way inline connector and the TFP manual valve position switch. If the parameter displays No, test the TCC release switch signal circuit for a short to ground between the TCM and the automatic transmission 20-way inline connector.
4. Inspect for the following conditions that would cause TCC release pressure to be present when the TCC is applied:
   • The turbine shaft O-ring seal leaking
   • The turbine shaft oil seal rings missing or damaged

     Refer to Torque Converter Assembly Removal .

   • The TCC control valve damaged

     Refer to Control Valve Body Disassemble (Without Touch Activated Power) or Control Valve Body Disassemble (With Touch Activated Power) .

   • The #1 checkball damaged
   • The spacer plate release exhaust blocked with debris

     Refer to Control Valve Body and Spacer Plate Assemble .

   • The case cover or spacer plate gaskets improperly installed

     Refer to Case Cover Removal .

If any of the conditions are found, repair as necessary.