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

DTC DETECTING CONDITION:

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

TROUBLE SYMPTOM:

Erroneous idling

CAUTION: After repairing or replacing the defective part, perform the Clear Memory Mode < Ref. to OPERATION , Clear Memory Mode. > and Inspection Mode < Ref. to PROCEDURE , Inspection Mode. >.

WIRING DIAGRAM:

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

DIAGNOSIS PROCEDURE

Step	Check	Yes	No
1 CHECK ANY OTHER DTC ON DISPLAY.	Is any other DTC displayed?	Check DTC using "List of Diagnostic Trouble Code (DTC)". < Ref. to LIST OF DIAGNOSTIC TROUBLE CODE (DTC) . >	Go to step 2 .
2 CHECK INPUT SIGNAL OF ECM. Turn the ignition switch to ON. Place the select lever other than "N" and "P" range. Measure the voltage between ECM and chassis ground. Connector & terminal (B136) No. 31 (+) - Chassis ground (-):	Is the voltage more than 10 V?	Even if the malfunction indicator light illuminates, 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 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 (B136) No. 31 - Chassis ground: (B136) No. 6 - Chassis ground:	Is the resistance more than 1 MΩ?	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 of harness between transmission harness connector and engine ground. Connector & terminal (T3) No. 11 - Engine ground:	Is the resistance more than 1 MΩ?	Go to step 5.	Repair the ground short circuit of harness between transmission harness connector and inhibitor switch connector.
5 CHECK INHIBITOR SWITCH. Measure the resistance between inhibitor switch connector receptacles terminals with select lever at other than "N" or "P" range. Terminals No. 7 - No. 12:	Is the resistance more than 1 MΩ?	Go to step 6.	Replace the inhibitor switch. < Ref. to INHIBITOR SWITCH . >
6 CHECK SELECT CABLE CONNECTION.	Is there any fault in the select cable connection to the inhibitor switch?	Repair the select cable connection. < Ref. to INSPECTION , Select Cable. >	Contact the SOA service center.