Part 2

Flowchart C-8B (2 Of 2):

Wiring Diagram for Chart C-8B Torque Converter Clutch:

CIRCUIT DESCRIPTION
The 3rd gear switch in this vehicle is open in 3rd and 4th gear. The Electronic Control Module (ECM) uses this signal to disengage the Torque Converter Clutch (TCC) when going into a downshift.
The fourth gear switch is open in fourth gear.

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

1. Some "Scan" tools display the state of these switches in different ways. Be familiar with the type of tool being used. Since both switches should be in the closed state during this test, the tool should read the same for either the 3rd or 4th gear switch.

2. Determines whether the switch or signal circuits open. The circuit can be checked for an open by measuring the voltage (with a voltmeter) at the TCC connector. Should be about 12 volts.

3. Because the switch(es) should be grounded in this step, disconnecting the TCC connector should cause the "Scan" switch state to change.

4. The switch state should change when the vehicle shifts into 3rd gear.

DIAGNOSTIC AIDS
If vehicle is road tested because of a TCC related problem, be sure the switch states do not change while in 4th gear because the TCC will disengage. If switches change state, carefully check wire routing and connections.