DTC Troubleshooting: B1225 (A)

DTC indicator A or DTC B1225:  An Open in the In-car Temperature Sensor Circuit


1.Clear the DTC.

2.Turn the ignition switch OFF, and then ON.

3.Operate the climate control system is several modes.

4.Check the DTCs.

Is DTC A or B1225 indicated?


YES - Go to 5.


NO - Intermittent failure, check for loose wires or poor connections on the in-car temperature sensor circuit.n


5.Remove the in-car temperature sensor and test it.

Does the in-car temperature sensor test OK?


YES - Go to 6.


NO - Replace the  in-car temperature sensor.n


6.Disconnect climate control unit connector A (22P).

7.Check for continuity between the No. 11 terminal of climate control unit connector A (22P) and the No. 2 terminal of the in-car temperature sensor 2P connector.

Is there continuity?


YES - Go to 8.


NO - Repair open in the wire between the climate control unit and the in-car temperature sensor.n

8.Check for continuity between the No. 15 terminal of climate control unit connector A (22P) and the No. 1 terminal of the in-car temperature sensor 2P connector.

Is there continuity?


YES - Go to 9.


NO - Repair open in the wire between the climate control unit and the in-car temperature sensor.n


9.Perform the A/C communication in the Self-Diagnostic Function to obtain the IS-BUS communication verification status.

Is the communication OK?


YES - Check for loose wires or poor connections at climate control unit connector A (22P) and at the in-car temperature sensor 2P connector. If the connections are good, substitute a known-good climate control unit and printed circuit board, and recheck. If the symptom/indication goes away, replace the original climate control unit and printed circuit board.n


NO - Check for loose wires or poor connections at climate control unit connector A (22P) and at the in-car temperature sensor 2P connector. If the connections are good, substitute a known-good climate control unit, and recheck. If the symptom/indication goes away, replace the original climate control unit.n