ENGINE (DIAGNOSTICS)(H4DO) > Diagnostic Procedure with Diagnostic Trouble Code (DTC)

DTC P0851 NEUTRAL SWITCH INPUT CIRCUIT LOW (MT MODEL)

DTC DETECTING CONDITION:

Detected when two consecutive driving cycles with fault occur.

TROUBLE SYMPTOM:

Improper idling

CAUTION:

After repairing or replacing the defective part, perform the Clear Memory Mode and Inspection Mode .

WIRING DIAGRAM:

STEPCHECKYESNO

1.CHECK INPUT SIGNAL OF ECM.

1) Turn the ignition switch to ON.

2) Place the shift lever in a position other than neutral.

3) Measure the voltage between ECM and chassis ground.

Connector & terminal

(B135) No. 9 (+) — Chassis ground (−):

Is the voltage 10 V or more?

Check for poor contact of the ECM connector.

2.CHECK HARNESS BETWEEN ECM AND NEUTRAL POSITION SWITCH CONNECTOR.

1) Turn the ignition switch to OFF.

2) Disconnect the connectors from ECM and neutral position switch.

3) Measure the resistance between ECM and chassis ground.

Connector & terminal

(B135) No. 9 — Chassis ground:

Is the resistance 1 MΩ or more?

Replace the neutral position switch.

Repair the short circuit to ground harness between ECM and neutral position switch connector.