DTC P0852: Park/Neutral Switch Input Circuit High: Notes

DTC detecting condition: 

Detected when two consecutive driving cycles with fault occur.

Trouble symptom: 

Improper idling

Engine Electrical System Ref. to WIRING SYSTEM>Engine Electrical System>WIRING DIAGRAM .

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK INPUT SIGNAL OF ECM  .
   1. Turn the ignition switch to ON.
   2. Place the gear shift lever in neutral.
   3. Measure the voltage between ECM connector and chassis ground.

      Connector & terminal

      (B136) No. 35 (+) - Chassis ground (-):

   Is the voltage less than 1 V?

   Yes: Repair the poor contact of ECM connector.

   No: GO to  2.

2. CHECK HARNESS BETWEEN ECM AND NEUTRAL POSITION SWITCH CONNECTOR  .
   1. Turn the ignition switch to OFF.
   2. Disconnect the connector from ECM.
   3. Disconnect the connector from the neutral position switch.
   4. Measure the resistance of harness between ECM connector and transmission harness connector.

      Connector & terminal

      (B136) No. 35 - (T12) No. 1:

      (B136) No. 4 - (T12) No. 2:

   Is the resistance less than 1 Ω?

   Yes: Go to  3.

   NO: Repair the harness and connector.

   NOTE: In this case, repair the following item:

   • Open circuit in harness between ECM connector and transmission harness connector
   • Poor contact of coupling connector
3. CHECK NEUTRAL POSITION SWITCH  .
   1. Place the gear shift lever in neutral.
   2. Measure the resistance between transmission harness connector terminals.

      Connector & terminal

      (T2) No. 1 - (T2) No. 2:

   Is the resistance less than 1 Ω?

   Yes: Repair the poor contact of transmission harness connector.

   No: Replace the neutral position switch. Ref. to MANUAL TRANSMISSION AND DIFFERENTIAL(6MT) (TY85)>Neutral Position Switch .