Transmission Position Sensor/Switch: Testing and Inspection

Chart C-1A - Gear Selector Switch Operation:

Wiring Diagram for Chart C-1A - Gear Selector Switch Operation:

CHART C-1A - GEAR SELECTOR SWITCH

Circuit Description:

The Gear Selector Switch contacts are a part of the Neutral Start Switchand are closed completing the path to ground the BCM in park or neutral, and are open in drive or reverse ranges.

The ECM supplies ignition voltage through a current limiting resistor to CKT 434 and senses a closed switch when the voltage on CKT 434 drops to less than one volt (grounded through BCM).

The Gear Selector Signal is used as one of the inputs by the ECM to control;

a. Idle Air Control
b. VSS Diagnostics
c. EGR
d. TCC




Test Description: The following numbered steps correspond with the step numbers on the diagnostic chart.

1. Checks for proper Gear Selector Switch operation.

2. Identifies the fault as being either a Gear Selector Switch or ECM/ECM wiring failure.

3. Verifies integrity of ECM and related circuitry. If OK, display will read "LO", indicating faulty switch or improper switch adjustment.

4. Checks to see if the fault is in the wiring or ECM.