Shift Mode Switch

Circuit Description
The Shift Mode Switch (Driver Select Shift Switch) enables the operator to select a more aggressive shift pattern within the midrange throttle position (40-80%). Depressing the switch provides a ground path for ignition voltage from the PCM. While the PCM is in Performance mode, shifts are firmer, and slightly delayed (approximately 1-3 mph). Return to Normal mode by depressing the switch a second time.


Diagnostic Aids
If you do not perceive an increased performance while in Performance mode, use Snapshot on the scan tool.

1. Record data with the vehicle in Normal mode.

2. Record data with the vehicle in Performance mode.

3. Review the data sets for differences in the following items during upshifts and downshifts:

^ Pressure Control Solenoid Valve (PC Sol. Valve) duty cycle

^ vehicle speed

^ commanded gear


Test Description
1. This Step tests the switch function.

4. This Step isolates the switch, and verifies that the power circuit and ground circuit are working properly. If the scan tool displays Perf., then the circuitry and the PCM are working properly.

5. This Step verifies that no open exits in the power feed circuit from the PCM to the switch.

6. This Step inspects the DK BLU wire circuit 1493 for an open or a short to power.

7. This Step inspects the DK BLU wire circuit 1493 for a short to ground if the scan tool displayed Perf.

8. This Step inspects the BLK wire circuit 150 for an open.

9. This Step replaces the shift mode switch. Previous Steps verified that the power circuit and ground circuit are not open or shorted to ground.

10. This Step replaces the PCM. Previous Steps verified that neither the switch nor the applicable circuitry is faulty.

11. This Step road tests the vehicle. Record snapshot data from A/T 2 data list with the switch in the Normal, then the Performance positions. Observe the scan tool PC Duty Cycle, Shift TP Angle, MPH, and Commanded Gear. In both the normal and the performance mode, do not vary the TP shift angle by more than 2%. Compare the performance and normal modes. The PC duty cycle should be lower, and the vehicle speed should be higher in the performance mode.