DTC Troubleshooting: B1230 (F and AUTO)
  1. Check for continuity between heater control unit connector A (28P) No. 25 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 sunlight sensor.■
NO -
Go to Step 10 .
  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 -
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. ■