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DTC P0851 NEUTRAL SWITCH INPUT CIRCUIT LOW (MT MODEL)

DTC P0851 NEUTRAL SWITCH INPUT CIRCUIT LOW (MT MODEL)

DTC DETECTING CONDITION:


• Two consecutive driving cycles with fault

• GENERAL DESCRIPTION


TROUBLE SYMPTOM:

Erroneous idling

Important

After repair or replacement of faulty parts, conduct Clear Memory Mode and Inspection Mode .


WIRING DIAGRAM:


CHECK INPUT SIGNAL FOR ECM.

Turn the ignition switch to ON.

Place the shift lever in a position except for neutral.

Measure the voltage between ECM and chassis ground.

Connector & terminal

(B134) No. 8 (+) — Chassis ground (−):

Is the voltage more than 10 V?

Yes


No


CHECK INPUT SIGNAL FOR ECM.

Place the shift lever in neutral.

Measure the voltage between ECM and chassis ground.

Connector & terminal

(B134) No. 8 (+) — Chassis ground (−):

Is the voltage less than 1 V?

Yes


No


CHECK POOR CONTACT.

Check poor contact in ECM connector.

Is there poor contact in ECM connector?

Yes

Repair poor contact in ECM connector.


No

Contact Service Center.


CHECK NEUTRAL POSITION SWITCH.

Turn the ignition switch to OFF.

Disconnect the connector from transmission harness.

Place the shift lever in a position except for neutral.

Measure the resistance between transmission harness and connector terminals.

Connector & terminal

(T9) No. 1 — No. 3:

Is the resistance more than 1 MΩ?

Yes


No

Repair short circuit in transmission harness or replace neutral position switch.


CHECK NEUTRAL POSITION SWITCH.

Place the shift lever in neutral.

Measure the resistance between transmission harness connector terminals.

Is the resistance less than 1 Ω?

Yes


No

Repair short circuit in transmission harness or replace neutral position switch.


CHECK HARNESS BETWEEN ECM AND NEUTRAL POSITION SWITCH CONNECTOR.

Measure the resistance between ECM and chassis ground.

Connector & terminal

(B134) No. 8 — Chassis ground:

Is the resistance more than 1 MΩ?

Yes


No

Repair ground short circuit in harness between ECM and transmission harness connector.


CHECK HARNESS BETWEEN ECM AND NEUTRAL POSITION SWITCH CONNECTOR.

Disconnect the connector from ECM.

Measure the resistance of harness between ECM and transmission harness connector.

Connector & terminal

(B134) No. 8 — (B128) No. 1:

Is the resistance less than 1 Ω?

Yes


No

Repair open circuit in harness between ECM and transmission harness connector.


CHECK HARNESS BETWEEN ECM AND NEUTRAL POSITION SWITCH CONNECTOR.

Measure the resistance of harness between transmission harness connector and engine ground.

Connector & terminal

(B128) No. 1 — Engine ground:

Is the resistance less than 5 Ω?

Yes


No

Repair open circuit between transmission harness connector and engine ground terminal.


CHECK POOR CONTACT.

Check poor contact in transmission harness connector.

Is there poor contact in transmission harness connector?

Yes

Repair poor contact in transmission harness connector.


No

Contact Service Center.