DTC B1433: Ambient Temperature Sensor Circuit Short-Circuit (Air-Conditioner)

DTC detecting condition: 

Short circuit in the ambient sensor (CAN data) is detected for 3 seconds or more.

Trouble symptom: 

Ambient temperature is falsely recognized, and the compartment temperature is adjusted.

Wiring diagram: 

Air conditioning system Refer to WIRING SYSTEM>AIR CONDITIONING SYSTEM>WIRING DIAGRAM .

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK CONNECTOR. 
   1. Check the connecting conditions of combination meter connector and ambient sensor connector.
   2. Read the DTC using Subaru Select Monitor. Refer to HVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)>READ DIAGNOSTIC TROUBLE CODE (DTC) .

   Is DTC B1433 displayed?

   Yes:  Go to  2.

   No  Even if DTC is displayed, the circuit has returned to a normal condition at this time. Reproduce the failure, and then perform the diagnosis again.

   NOTE: In this case, temporary poor contact of connector, temporary open or short circuit of harness may be the cause.
2. CHECK AMBIENT SENSOR. 
   1. Disconnect the ambient sensor. Refer to HVAC SYSTEM (HEATER, VENTILATOR AND A/C)>AMBIENT SENSOR>REMOVAL .
   2. Read the DTC using Subaru Select Monitor. Refer to HVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)>READ DIAGNOSTIC TROUBLE CODE (DTC) .

   Is DTC B1432 displayed?

   Yes  Replace the ambient sensor. Refer to HVAC SYSTEM (HEATER, VENTILATOR AND A/C)>AMBIENT SENSOR>REMOVAL .

   No:  Go to  3.

3. CHECK HARNESS. 
   1. Turn the ignition switch to ON.
   2. Using the tester, measure the voltage between terminals.

   Connector & terminal 

   (F78) No. 1 (+) - No. 2 (-):

   Is the voltage 4.5 - 5.0 V?

   Yes  Even if DTC is displayed, the circuit has returned to a normal condition at this time. Reproduce the failure, and then perform the diagnosis again.

   NOTE: In this case, temporary poor contact of connector, temporary open or short circuit of harness may be the cause.

   No:  Go to  4.

4. CHECK HARNESS (SHORTED BETWEEN LINES). 
   1. Disconnect the connector from the combination meter.
   2. Using a tester, check continuity between terminals.

   Connector & terminal 

   (F78) No. 2 - No. 1:

   Is there continuity?

   Yes  Repair or replace the short circuit of the harness.

   No  Replace the combination meter. Refer to INSTRUMENTATION/DRIVER INFO>COMBINATION METER>REMOVAL .