DTC P0851: Park/Neutral Switch Input Circuit Low: Notes

WARNING: This page is about a different variant/trim than selected.

DTC detecting condition:

Detected when two consecutive driving cycles with fault occur.

Trouble symptom:

Improper idling

CAUTION: After servicing or replacing faulty parts, perform Clear Memory Mode Ref. to OPERATION , Clear Memory Mode, and Inspection Mode Ref. to PROCEDURE , Inspection Mode.

Wiring diagram:

Engine Electrical System Ref. to WIRING DIAGRAM , Engine Electrical System.

Fig 1: Park/Neutral Switch Wiring Diagram

Courtesy of SUBARU OF AMERICA, INC.

Step	Check	Yes	No
1 CHECK SELECT CABLE.	Is there any fault in select cable?	Repair or adjust the select cable. Ref. to SELECT CABLE	Go to step 2
2 CHECK INPUT SIGNAL OF ECM. Turn the ignition switch to ON. Place the select lever in other than "P" range and "N" range. Measure the voltage between ECM connector and chassis ground. Connector & terminal (B134) No. 5 (+) - Chassis ground (-):	Is the voltage 10 V or more?	Repair the poor contact of ECM connector.	Go to step 3
3 CHECK HARNESS BETWEEN ECM AND TRANSMISSION HARNESS CONNECTOR. Turn the ignition switch to OFF. Disconnect the connector from ECM. Disconnect the connector from inhibitor switch. Measure the resistance between ECM connector and chassis ground. Connector & terminal (B134) No. 5 - Chassis ground:	Is the resistance 1 MΩ or more?	Replace the inhibitor switch. Ref. to INHIBITOR SWITCH	Repair the short circuit to ground in harness between ECM connector and inhibitor switch connector.