Part 1 of 3

Chart C-8B - Part 1 Of 3:

Transmission Control Wiring:

CIRCUIT DESCRIPTION
The purpose of the automatic transaxle torque converter clutch 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 is a solenoid located inside the automatic transaxle which is controlled by the ECM.

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

The TCC will engage on a warm engine under given road load in 2nd, 3rd and 4th gears. TCC will engage when:
^ Engine warmed up and in "Closed Loop" condition.
^ Vehicle speed above a calibrated value (about 45 mph - 72 km/h).
^ Throttle position not changing, indicating a steady road speed.
^ Brake switch closed.



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

1. This test checks the functional operation of the TCC circuit.

2. This test determines if there is B+ at terminal "A". If there is no B+, check 10 amp (IGN) fuse.

3. This test checks the TCC control driver in the ECM.

4. This test confirms that the ECM has the ability to turn the TCC "ON."


DIAGNOSTIC AIDS:
A Tech 1 (or equivalent) scan tool only indicates when the ECM has turned "ON" the TCC driver, and this does not confirm that the TCC has engaged. To determine if TCC is functioning properly, engine RPM should decrease when the Tech 1 (or equivalent) scan tool indicates the TCC driver has turned "ON."