DTC P0851 Park/Neutral Switch Input Circuit Low (At Model): Wiring Diagram

Engine electrical system, 2.5 L model (without push button start). See appropriate SYSTEM WIRING DIAGRAM article.
Engine electrical system, 2.5 L model (with push button start). See appropriate SYSTEM WIRING DIAGRAM article.

Fig 1: Park/Neutral Switch Input - Circuit Diagram (AT Model)
Courtesy of SUBARU OF AMERICA, INC.

DIAGNOSTIC PROCEDURE

Step	Check	Yes	No
1 CHECK SELECT CABLE.	Is there any fault in select cable?	Repair or adjust the select cable. Refer 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 and chassis ground. Connector & terminal (B137) No. 16 (+) - 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 connectors from ECM and transmission harness connector (T3). Measure the resistance between ECM and chassis ground. Connector & terminal (B137) No. 16 - Chassis ground:	Is the resistance 1 MΩ or more?	Go to step 4 .	Repair the ground short circuit of harness between ECM and transmission harness connector.
4 CHECK TRANSMISSION HARNESS CONNECTOR. Disconnect the connector from inhibitor switch. Measure the resistance between transmission harness connector and engine ground. Connector & terminal (T3) No. 16 - Engine ground:	Is the resistance 1 MΩ or more?	Replace the inhibitor switch. Refer to INHIBITOR SWITCH .	Repair short circuit to ground in harness between transmission harness connector and inhibitor switch connector.