DTC Troubleshooting: B1229 (E and AUTO)
  1. Check for continuity between heater control unit connector B (12P) No. 10 terminal and the sunlight sensor 2P connector No. 2 terminal.
Is there continuity?
YES -
Go to Step 10 .
NO -
Repair open in the wire between the heater control unit and the sunlight sensor.■
  1. Reconnect the sunlight sensor 2P connector.
  1. Reconnect heater control unit connectors A (28P) and B (12P).
  1. Test the sunlight sensor.
Is the sunlight sensor OK?
YES -
Check for loose wires or poor connections at heater control unit connector and at the sunlight sensor 2P connector. If the connections are good, substitute a known-good heater control unit, and recheck. If the symptom/indication goes away, replace the original heater control unit .■
NO -
Replace the sunlight sensor. ■