DTC P0851 - Neutral Switch Input Circuit Low (At Model) -

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

DTC DETECTING CONDITION:
- Two consecutive driving cycles with malfunction
TROUBLE SYMPTOM:
- Erroneous idling
CAUTION: After repair or replacement of malfunctioning parts, conduct Clear Memory Mode < Ref. to OPERATION , CLEAR MEMORY MODE > and INSPECTION MODE < Ref. to OPERATION , INSPECTION MODE. >
WIRING DIAGRAM:

Fig 1: Neutral Switch Input Wiring Diagram
Courtesy of SUBARU OF AMERICA, INC.

DIAGNOSTIC PROCEDURE

Step	Check	Yes	No
1 CHECK ANY OTHER DTC ON DISPLAY.	Is any other DTC displayed?	Inspect the relevant DTC using "List of Diagnostics Trouble Code (DTC)". < Ref. to LIST OF DIAGNOSTIC TROUBLE CODE (DTC) . >	Go to step 2.
2 CHECK INPUT SIGNAL FOR ECM. Turn ignition switch to ON. Place the select lever in any other than "P" or "N" range. Measure voltage between ECM and chassis ground. Connector & terminal (B136) No. 21 (+) - Chassis ground (-):	Is the measured value within 4.5 to 5.5 V?	Even if MIL lights up, the circuit has returned to a normal condition at this time.	Go to step 3.
3 CHECK HARNESS BETWEEN ECM AND TRANSMISSION HARNESS CONNECTOR. Turn ignition switch to OFF. Disconnect connectors from ECM and transmission harness connector (T3). Measure resistance of harness between ECM connector and chassis ground. Connector & terminal (B136) No. 21 - Chassis ground:	Is the measured value more than 1 MΩ?	Go to step 4.	Repair ground short circuit in harness between ECM and transmission harness connector.
4 CHECK TRANSMISSION HARNESS CONNECTOR. Disconnect connector from inhibitor switch. Measure resistance of harness between transmission harness connector and engine ground. Connector & terminal (T3) No. 12 - Engine ground:	Is the measured value more than 1 MΩ?	Go to step 5.	Repair ground short circuit in harness between transmission harness and inhibitor switch connector.
5 CHECK INHIBITOR SWITCH. Measure resistance between inhibitor switch connector terminals in select lever in any other than "P" or "N" position. Terminals No. 7 - No. 12:	Is the measured value more than 1 MΩ?	Go to step 6.	Replace inhibitor switch. < Ref. to INHIBITOR SWITCH . >
6 CHECK SELECTOR CABLE CONNECTION.	Is there any malfunction in selector cable connection to inhibitor switch?	Repair selector cable connection. < Ref. to SELECT CABLE . >	Contact with SOA service center. NOTE: Inspection by DTM is required, because probable cause is deterioration of multiple parts.