B1226

DTC Troubleshooting: B1226 (B and AUTO)

DTC B1226 or DTC indicator B and AUTO:

A Short in the In-Car Temperature Sensor Circuit

1. Clear the DTCs with the HDS.

2. Turn the ignition switch to LOCK (0) and then back to ON (II).

3. Do the self-diagnostic function with the HDS or the climate control unit.

4. Check for DTCs.

Is DTC B1226 or B and AUTO indicated?

YES -

Go to step 5.

NO -

Intermittent failure, check for loose wires or poor connections in the in-car temperature sensor circuit.�

5. Turn the ignition switch to LOCK (0).

6. Remove the humidity/in-car temperature sensor Humidity/In-Car Temperature Sensor Replacement, and test it.

Is the in-car temperature sensor OK?

YES -

With the in-car temperature sensor disconnected, go to step 7.

NO -

Replace the humidity/in-car temperature sensor Humidity/In-Car Temperature Sensor Replacement.�

7. Disconnect the climate control unit 36P connector.

8. Check for continuity between climate control unit 36P connector terminal No. 20 and body ground.





Is there continuity?

YES -

Repair a short to body ground in the wire between the climate control unit and the in-car temperature sensor.�

NO -

Go to step 9.

9. Check for continuity between climate control unit 36P connector terminals No. 1 and No. 20.





Is there continuity?

YES -

Repair a short in the wires between the climate control unit and the in-car temperature sensor.�

NO -

Substitute a known-good climate control unit, and recheck. If the symptom/indication goes away, replace the original climate control unit Climate Control Unit Removal/Installation.�