Part 1 of 2

Chart C-8A Part 1 Of 2:

Chart C-8A Wiring Diagram:

CIRCUIT DESCRIPTION:

The purpose of the 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 and the fuel economy of a manual transaxle. The heart of the system is a solenoid located inside the transaxle which is controlled by the ECM.

When the solenoid coil is activated ("ON,") the torque converter clutch is applied which results in straight through mechanical coupling from the engine to the wheels. When the transaxle (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).

Each gear switch opens when the appropriate clutch is applied. All gear switches are open in fourth gear.

TCC will engage when:

^ Engine warmed up.
^ Vehicle speed above a calibrated value (about 28 mph 45 km/h).
^ Throttle position sensor output not changing, indicating a steady road speed.
^ Brake switch closed.

TEST DESCRIPTION: Numbers below refer to circled numbers on the diagnostic chart.

1. Checks fuse, brake switch and B+ circuit to the TCC solenoid.

2. Checks availability of B+ on circuit 420.

3. Electrical circuits have checked out. If there is a TCC engagement problem, diagnose and repair transmission problem.

DIAGNOSTIC AIDS:

The "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, road test the vehicle. Engine rpm should decrease when the "Scan" indicates the TCC driver has turned "ON."