Without Transaxle Test Box

Torque Converter Clutch Diagnostic Chart:

Torque Converter Clutch Circuit:

CIRCUIT DESCRIPTION
The purpose of the Torque Converter Clutch (TCC) feature is to eliminate the power loss of the torque converter when the vehicle is in a cruise condition. This allows the convenience of the automatic transaxle and the fuel economy of a manual transaxle. The heart of the system consists of two Powertrain Control Module (PCM) controlled solenoids located inside the transaxle.

When the apply solenoid coil is activated "ON," the TCC is applied which results in a straight through mechanical coupling from the engine to the wheels. When the apply solenoid coil is deactivated "OFF," the TCC is released which allows the torque converter to operate in the conventional manner (fluid coupling between engine and transaxle).

The TCC Pulse Width Modulated (PWM) solenoid varies the hydraulic pressure at the converter clutch regulator valve to make locking and unlocking of TCC smoother. TCC will engage if:
^ Engine warmed up.
^ Vehicle speed above a calibrated value (about 28 mph).
^ Throttle position sensor output not changing, indicating a steady road speed.
^ Brake switch closed.
^ Vehicle is in 3rd or 4th gear.

Or

^ Vehicle is operating in "Hot Mode," which will cause the TCC to be engaged in 2nd gear.

CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.

Note: When connecting a test light or Digital Voltmeter (DVM) to the connectors, use connector test adapter kit J 35616 or extension harness J 38835 to avoid damaging the connector terminals.

1. Determines whether fault is caused by a faulty solenoid or control circuit.
2. Checks availability of B+ on CKT 241.
3. Checks the PCM's capability to pulse the PWM solenoid "ON" and "OFF"
4. Electrical circuits have checked out. If there is a TCC engagement problem, refer to Transmission Control Systems.

DIAGNOSTIC AIDS
The Tech 1 scan tool only indicates when the PCM has commanded the TCC solenoid driver "ON" and does not confirm that the TCC has engaged. To determine if TCC is functioning properly, road test the vehicle. Engine RPM should decrease when the scan tool indicates the TCC driver has turned "ON".

The TCC may engage in 2nd gear if the vehicle is operating in "Hot Mode," "Hot Mode" operation will be in effect when transaxle temperature exceeds 130°C (266°F).