( TL19E00K733000Y1225FAAT00 )

DTC Troubleshooting: B1225 (A and AUTO)

DTC B1225 or DTC indicator A and AUTO:
An Open 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. Do the self-diagnostic with the HDS or the heater control unit.

1. Check for DTCs.

Is DTC B1225 or A and AUTO indicated?

YES | - | Go to Step 5 .
NO | - | Intermittent failure; check for loose wires or poor connections on the in-car temperature sensor circuit.■

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

1. Remove the in-car temperature sensor, and test it.

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 the in-car temperature sensor 2P connector No. 1 terminal.

Is there continuity?

YES | - | Go to Step 9 .
NO | - | Repair open in the wire between the heater control unit and the in-car temperature sensor.■

1. Check for continuity between heater control unit connector B (12P) No. 10 terminal and the in-car temperature sensor 2P connector No. 2 terminal.

Is there continuity?

YES | - | Check for loose wires or poor connections at heater control unit connectors A (28P), B (12P), and at the in-car temperature 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 | - | Repair open in the wire between the heater control unit and the in-car temperature sensor.■