Grand Prix V6-191 3.1L (1989)
Chart C-8C Wiring Diagram
CIRCUIT DESCRIPTION:
The purpose of the automatic transmission torque converter clutch 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. The heart of the system
is a solenoid located inside the automatic transmission 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 transmission. When the transmission 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 transmission). The TCC will engage on a warm engine under given road load in 2nd, 3rd, and
4th gears.
The TCC will engage when:
^
Engine warmed up and in closed loop.
^
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.
This test checks the functional operation of the TCC circuit.
2.
This test checks the TCC control driver in the ECM.
3.
This test will confirm that there is battery voltage to terminal "A."
4.
This test confirms that the ECM has the ability to turn the TCC "ON."
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."
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