DTC P0851 Neutral Switch Input Circuit Low (At Model)

DTC DETECTING CONDITION:

Two consecutive driving cycles with fault
GENERAL DESCRIPTION < Ref. to DTC P0851 NEUTRAL SWITCH INPUT CIRCUIT LOW (AT MODEL) , Diagnostic Trouble Code (DTC) Detecting Criteria. >

TROUBLE SYMPTOM:

Erroneous idling

CAUTION: After repair or replacement of faulty parts, conduct Clear Memory Mode < Ref. to , OPERATION , Clear Memory Mode. > and Inspection Mode < Ref. to , PROCEDURE , Inspection Mode. >.

WIRING DIAGRAM:

Fig 1: Wiring Diagram - Neutral Switch Input Circuit Low (AT Model)

Courtesy of SUBARU OF AMERICA, INC.

DTC P0851 DIAGNOSTIC PROCEDURE

Step	Check	Yes	No
1 CHECK INPUT SIGNAL FOR ECM. Turn the ignition switch to ON. Place the select lever except for "N" and "P" ranges. Measure the voltage between ECM and chassis ground. Connector & terminal (B137) No. 9 (+) - Chassis ground (-):	Is the voltage 4.5 - 5.5 V?	Even if malfunction indicator light lights up, the circuit has returned to a normal condition at this time.	Go to step 2.
2 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 of harness between ECM connector and chassis ground. Connector & terminal (B137) No. 9 - Chassis ground:	Is the resistance more than 1 MΩ?	Go to step 3.	Repair ground short circuit in harness between ECM and transmission harness connector.
3 CHECK TRANSMISSION HARNESS CONNECTOR. Disconnect the connector from inhibitor switch. Measure the resistance of harness between transmission harness connector and engine ground. Connector & terminal (73) No. 12 - Engine ground:	Is the resistance more than 1 MΩ?	Go to step 4.	Repair ground short circuit in harness between transmission harness and inhibitor switch connector.
4 CHECK INHIBITOR SWITCH. Measure the resistance between inhibitor switch connector the receptacle's terminals in select lever except for "N" and "P" range. Terminals No. 7 - No. 12:	Is the resistance more than 1 MΩ?	Go to step 5.	Replace the inhibitor switch. < Ref. to INHIBITOR SWITCH . >
5 CHECK SELECTOR CABLE CONNECTION.	Is there any fault in selector cable connection to inhibitor switch?	Repair selector cable connection. < Ref. to INSPECTION , Select Cable. >	Contact SOA Service Center.