Description and Diagnosis Procedure

SYSTEM: Park/Neutral Position Switch Circuit (Only for vehicles with A/T)


CIRCUIT DESCRIPTION

Park/Neutral Position Switch Circuit:

The Park/Neutral Position (PNP) switch goes on when the shift lever is in the "N" or "P" shift position. When it goes on the terminal NSW of the ECM is grounded to body ground via the starter relay and theft deterrent ECU, thus the terminal NSW voltage becomes 0.0 volts. When the shift lever is in the D, 2, L or R position, the ECM switch goes off, so the voltage of ECM terminal "NSW" becomes battery voltage, the voltage of the ECM internal power source.
If the shift lever is moved from the "N" position to the "D" position, this signal is used for air-fuel ratio correction and for idle speed control (estimated control), etc.

NOTE: When the Park/Neutral position switch is OFF, code "51" is output in the Test Mode diagnosis. (This is normal.)

DIAGNOSTIC PROCEDURE

NOTE: This diagnosis chart is based on premise that the engine will crank normally. If the engine will not crank, proceed to "Diagnosis By Symptom".

1. CHECK OUTPUT CONDITION OF DIAGNOSTIC TROUBLE CODE 51.
- If OK (normal code appears in "P" and code 51 appears in "D") proceed "Diagnosis By Symptom".
- If not OK (code 51 appears in both "P" and "D") proceed to step 2.
- If not OK (normal code appears in both "P" and "D") proceed to step 3.
2. CHECK FOR OPEN IN HARNESS AND CONNECTOR BETWEEN PNP SWITCH AND ECM.
- If OK check and replace ECM.
- If not OK repair or replace harness or connector.
3. CHECK PNP SWITCH.
- If OK check and replace ECM.
- If not OK replace PNP Switch.