DTC P257F: Engine Hood Switch Circuit High: Notes

DTC detecting condition :

Detected when two consecutive driving cycles with fault occur.

Trouble symptom :

Auto Start Stop does not operate.

Failure detection pattern :

"Primary" (high-priority diagnosis)

Warning light/indicator light :

Malfunction indicator light◦
Auto Start Stop warning light (yellow)◦

Wiring diagram :

Auto Start Stop Ref. to WIRING SYSTEM>AUTO START STOP>WIRING DIAGRAM .

Courtesy of SUBARU OF AMERICA, INC.

CAUTION: After servicing or replacing faulty parts, perform the last step of the basic diagnostic procedure. Ref. to AUTO START STOP (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE .

CHECK FUSE .
1. Turn the ignition switch to OFF.
2. Check the fuse (F/B fuse No. 26). Ref. to WIRING SYSTEM>INTERIOR LIGHT SYSTEM .
Is the check result OK?

Yes: GO TO 2.

No: Replace the fuse (F/B fuse No. 26).
CHECK FOR ANY OTHER DTC ON DISPLAY .
Turn the ignition switch to ON and wait for 40 seconds.

Is DTC B1012 displayed?

Yes: Perform the diagnosis according to the DTC. Ref. to BODY CONTROL (DIAGNOSTICS)>DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)>DTC B1012 BATTERY BACKUP POWER SUPPLY .

No: GO TO 3.
CHECK DATA MONITOR .
Read the data of [Hood SW (Hood Close Status)] with the front hood closed using the Subaru Select Monitor. Ref. to AUTO START STOP (DIAGNOSTICS)>DATA MONITOR .

Is [ON] displayed in [Hood SW (Hood Close Status)]?

Yes: GO TO 4.

No: GO TO 5.
CHECK DATA MONITOR .
Read the data of [Hood SW (Hood Open Status)] with the front hood opened using the Subaru Select Monitor. Ref. to AUTO START STOP (DIAGNOSTICS)>DATA MONITOR .

Is [ON] displayed in [Hood SW (Hood Open Status)]?

Yes: The circuit has returned to a normal condition at this time. Reproduce the failure, and then perform the diagnosis again.

No: GO TO 7.
CHECK HARNESS BETWEEN BODY INTEGRATED UNIT AND HOOD SWITCH (CLOSED SIDE) CONNECTOR .
1. Turn the ignition switch to OFF.
2. Disconnect the connector of body integrated unit.
3. Disconnect the connector of hood switch.
4. Measure the resistance between the body integrated unit connector and hood switch connector.
  Connector & terminal
  
  (B73) No. 3 - (B103) No. 1:
Is the resistance less than 1 Ω?

Yes: GO TO 6.

No: Repair the open circuit of harness between body integrated unit and hood switch (closed side) connector.
CHECK HOOD SWITCH (CLOSED SIDE) CONNECTOR .
1. Connect all connectors.
2. Check continuity in the hood switch (closed side) connector.
  Connector & terminal
  
  (B103) No. 1 - (B103) No. 2:
Is there continuity when the front hood is closed?

Yes: Check for poor contact of the body integrated unit connector and hood switch (closed side) connector. If there is no abnormality, replace the body integrated unit. Ref. to BODY CONTROL/COMMUNICATION SYSTEM>BODY INTEGRATED UNIT .

No: Replace the front hood lock assembly. Ref. to SECURITY AND LOCKS>FRONT HOOD LOCK ASSEMBLY .
CHECK HARNESS BETWEEN BODY INTEGRATED UNIT AND HOOD SWITCH (OPEN SIDE) CONNECTOR .
1. Turn the ignition switch to OFF.
2. Disconnect the connector of body integrated unit.
3. Disconnect the connector of hood switch.
4. Measure the resistance between the body integrated unit connector and hood switch connector.
  Connector & terminal
  
  (B73) No. 4 - (B103) No. 3:
Is the resistance less than 1 Ω?

Yes: GO TO 8.

No: Repair the open circuit of harness between body integrated unit and hood switch (open side) connector.
CHECK HOOD SWITCH (OPEN SIDE) CONNECTOR .
1. Connect all connectors.
2. Check continuity in hood switch (open side) connector.
  Connector & terminal
  
  (B103) No. 3 - (B103) No. 2:
Is there continuity when the front hood is open?

Yes: Check for poor contact of the body integrated unit connector and hood switch (open side) connector. If there is no abnormality, replace the body integrated unit. Ref. to BODY CONTROL/COMMUNICATION SYSTEM>BODY INTEGRATED UNIT .

No: Replace the front hood lock assembly. Ref. to SECURITY AND LOCKS>FRONT HOOD LOCK ASSEMBLY .