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 DTC with the HDS.
  1. Turn the ignition switch to LOCK (0) and then to ON (II).
  1. Check for DTCs.
Is DTC B1226 or B and AUTO indicated?
YES -
Go to Step 5 .
NO -
Intermittent failure.■
  1. Turn the ignition switch to LOCK (0).
Is the in-car temperature sensor OK?
YES -
Go to Step 7 .
NO -
Replace the in-car temperature sensor .■
  1. Disconnect heater control unit connectors A (28P) and B (12P).
  1. Check for continuity between heater control unit connector A (28P) No. 26 terminal and body ground.
Is there continuity?
YES -
Repair short to body ground in the wire between the heater control unit and the in-car temperature sensor.■
NO -
Go to Step 9 .
  1. Check for continuity between heater control unit connector A (28P) No. 26 terminal and heater control unit connector B (12P) No. 10 terminal.
Is there continuity?
YES -
Repair short in the wires between the heater control unit and the in-car temperature sensor.■
NO -
Substitute a known-good heater control unit, and recheck. If the symptom/indication goes away, replace the original heater control unit .■