B257C

B257B, B257C AMBIENT SENSOR

DTC Logic


DTC DETECTION LOGIC

NOTE:
- If DTC is displayed along with DTC U1000, first perform the trouble diagnosis for DTC U1000. Refer to HAC55, "DTC Logic".
- If DTC is displayed along with DTC U1010, first perform the trouble diagnosis for DTC U1010. "DTC Logic" Control Unit.






DTC CONFIRMATION PROCEDURE


1. PERFORM DTC CONFIRMATION PROCEDURE

With CONSULT
1.Turn power switch ON.
2.Select "Self Diagnostic Result" mode of "HVAC" using CONSULT.
3.Check DTC.
Is DTC detected?
YES- Refer to "Diagnosis Procedure" .
NO- INSPECTION END


Diagnosis Procedure


1. CHECK AMBIENT SENSOR VOLTAGE SIGNAL

1.Turn power switch ON.
2.Operate the automatic air conditioning system.
3.Read voltage signal between A/C auto amp. harness connector terminals.





Is the inspection result normal?
YES- GO TO 7.
NO- GO TO 2.

2. CHECK AMBIENT SENSOR POWER SUPPLY

1.Turn power switch OFF.
2.Disconnect ambient sensor connector.
3.Turn power switch ON.
4.Check voltage between ambient sensor harness connector and ground.





Is the inspection result normal?
YES- GO TO 3.
NO- GO TO 5.

3. CHECK AMBIENT SENSOR GROUND CIRCUIT FOR OPEN

1.Turn power switch OFF.
2.Disconnect A/C auto amp. connector.
3.Check continuity between ambient sensor harness connector and A/C auto amp harness connector.





Is the inspection result normal?
YES- GO TO 4.
NO- Repair harness or connector.

4. CHECK AMBIENT SENSOR

Check ambient sensor. Refer to "Component Inspection" .
Is the inspection result normal?
YES- Replace A/C control (A/C auto amp.). Refer to "Removal and Installation" Service and Repair.
NO- Replace ambient sensor. Refer to "Removal and Installation" Service and Repair.

5. CHECK AMBIENT SENSOR POWER SUPPLY CIRCUIT FOR OPEN

1.Turn power switch OFF.
2.Disconnect A/C auto amp. connector.
3.Check continuity between ambient sensor harness connector and A/C auto amp. harness connector.





Is the inspection result normal?
YES- GO TO 6.
NO- Repair harness or connector.

6. CHECK AMBIENT SENSOR POWER SUPPLY CIRCUIT FOR SHORT

Check continuity between ambient sensor harness connector and ground.





Is the inspection result normal?
YES- Replace A/C control (A/C auto amp.). Refer to "Removal and Installation" Service and Repair.
NO- Repair harness or connector.

7. CHECK INTERMITTENT INCIDENT

Check intermittent incident. Refer to "Intermittent Incident" Intermittent Incident.
Is the inspection result normal?
YES- Replace A/C control (A/C auto amp.). Refer to "Removal and Installation" Service and Repair.
NO- Repair or replace malfunctioning parts.


Component Inspection


1. CHECK AMBIENT SENSOR

1.Remove ambient sensor. Refer to "Removal and Installation" Service and Repair.
2.Check resistance between ambient sensor terminals. Refer to applicable table for the normal value.





Is the inspection result normal?
YES- INSPECTION END
NO- Replace ambient sensor. Refer to "Removal and Installation" Service and Repair.