Part 2 of 2

Chart C-8A Part 2 Of 2:

Wiring Diagram:

CIRCUIT DESCRIPTION:

The 2nd gear switch in this vehicle is open in 2nd and 3rd gear. The ECM uses this 2nd gear signal to disengage the TCC when going into a downshift.

The 3rd gear switch should be open in 3rd gear.

1st gear = 2nd gear switch open
2nd gear signal switch closed
3rd gear signal switch closed.

2nd gear = 2nd gear switch closed
2nd gear signal switch opens
3rd gear signal switch closed

3rd gear = 2nd gear switch closed
2nd gear signal switch opens
3rd gear signal switch opens

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 2nd or 3rd gear switch.

2. Determines whether the switch or signal circuit is 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(s) should be grounded in this step, disconnecting the TCC connector should cause the "Scan" switch state to change.

4. This switch state should change when the vehicle shifts into 2nd gear.

DIAGNOSTIC AIDS:

If vehicle is road tested because of a TCC related problem, be sure the switch states do not change while in 3rd gear because the TCC will disengage. If switches change state, carefully check wire routing and connections.