1.CHECK CONNECTOR. 1) Check connecting condition of the A/C CM connector and in-vehicle sensor connector. 2) Read the DTC using Subaru Select Monitor. Read Diagnostic Trouble Code (DTC) | | Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC B1431 IN-VEHICLE (POST EVAPORATOR) TEMPERATURE SENSOR CIRCUIT SHORT-CIRCUIT | 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 IN-VEHICLE SENSOR. 1) Disconnect the in-vehicle sensor. In-Vehicle Sensor (Auto A/C Model) > REMOVAL 2) Read the DTC of the A/C CM using the Subaru Select Monitor. Read Diagnostic Trouble Code (DTC) | | Replace the in-vehicle sensor. In-Vehicle Sensor (Auto A/C Model) > REMOVAL | Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC B1431 IN-VEHICLE (POST EVAPORATOR) TEMPERATURE SENSOR CIRCUIT SHORT-CIRCUIT |
3.CHECK HARNESS. 1) Turn the ignition switch to ON. 2) Using the tester, measure the voltage between terminals. Connector & terminal (i173) No. 1 (+) — No. 2 (−): | Is the voltage 4.5 — 5.0 V- | 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. | Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC B1431 IN-VEHICLE (POST EVAPORATOR) TEMPERATURE SENSOR CIRCUIT SHORT-CIRCUIT |
4.CHECK HARNESS (SHORTED BETWEEN LINES). 1) Disconnect the connector from A/C CM. 2) Using a tester, check continuity between terminals. | | Repair or replace the short circuit of the harness. | Replace the A/C CM. Control Unit > REMOVAL |