Chart C-8 Torque Converter Clutch - 125C Transaxle

CIRCUIT DESCRIPTION
The purpose of the 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 transmission and the fuel economy of a manual transmission.

Fused battery ignition is supplied to the TCC solenoid through the brake switch, and transmission/transaxle third gear apply switch. The Engine Control Module (ECM) will engage TCC by grounding CKT 422 to energize the solenoid.

TCC will engage when:
^ Engine warmed up
^ Vehicle speed above a calibrated value.
^ Throttle position sensor output not changing, indicating a steady road speed.
^ Transmission third gear switch closed
^ Brake switch closed


CHART TEST DESCRIPTION
1. Light off confirms transmission third gear apply switch is open.

2. At 30 mph the transmission third gear switch should close. Test light will come on and confirm battery supply and closed brake switch.

3. Grounding the diagnostic terminal with engine "OFF" should energize the TCC solenoid. This test checks the capability of the ECM to control the solenoid.

4. Solenoids and relay's are turned "ON" or "OFF" by the ECM internal electronic switches called "drivers". Each driver is part of a group of four called "Quad-Drivers". Failure of one can damage any other driver within the set.

Before replacing ECM be sure to check the coil resistance of all solenoids and relays controlled by the ECM. See ECM wiring diagram for the solenoid(s) and relay(s) and the coil terminal identification.

When checking TCC solenoid be sure to raise drive wheels and run about 30 MPH to close third gear apply switch.