Transmission Position Sensor/Switch: Testing and Inspection

Chart C-1A Park/Neutral Position Switch Diagnosis (A/T Only):

Park/Neutral Switch Wiring Circuit:

CIRCUIT DESCRIPTION:
The Park/Neutral Position (PNP) switch contacts are a part of the neutral start switch and are closed to ground in park or neutral, and open in drive ranges.

The PCM 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.

The PCM uses the PNP signal as one of the inputs to control:
^ Idle Air Control (IAC).
^ Vehicle Speed Sensor (VSS) Diagnostics.

CHART TEST DESCRIPTION: Number(s) below refer to circled number(s) on the diagnostic chart.
1. Checks for a closed switch to ground in park position. Different makes of scan tools will read PNP differently. Refer to "Tool Operations" manual for type of display used.
2. Checks for an open switch in drive range.
3. Be sure Tech 1 scan tool indicates drive, even while wiggling shifter to test for an intermittent or misadjusted switch in drive range.