DTC B1255, B1257 [FULL-AUTO AIR CONDITIONER]SM2445593
DTC B1255, B1257 [FULL-AUTO AIR CONDITIONER]

id0702c1800600

DTC B1255, B1257

Ambient temperature sensor system

POSSIBLE CAUSE
• Ambient temperature sensor malfunction
• Open or short circuit in wiring harness between climate control unit and ambient temperature sensor

Diagnostic Procedure

STEP

INSPECTION

ACTION

1
• Inspect the ambient temperature sensor. (See AMBIENT TEMPERATURE SENSOR INSPECTION [FULL-AUTO AIR CONDITIONER].)
• Is it normal?
Yes
Go to the next step.
No
Replace the ambient temperature sensor.
2
• Disconnect the climate control unit connector and the ambient temperature sensor connector.
• Is there an open circuit in the wiring harness between the following terminals of the climate control unit and the ambient temperature sensor?
― 1L—B
― 1C—A
Yes
Repair the wiring harness.
No
Go to the next step.
3
• Is there a short circuit to ground in the wiring harness between climate control unit terminal 1L and ambient temperature sensor terminal B?
Yes
Repair the wiring harness.
No
Connect the climate control unit connector, then go to the next step.
4
• Turn the ignition switch to the ON position.
• Inspect the voltage at the following climate control unit terminal (wiring harness-side).
― Terminal 1L (ambient temperature sensor input signal)
• Is the voltage normal? ( Approx. 5 V)
Yes
The system is normal at present. (Clear the malfunction from the memory.)
No
Inspect the connection of the climate control unit connector.