DTC B1251, B1253


id070200800300

DTC B1251, B1253

Cabin temperature sensor system

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

Diagnostic Procedure

STEP

INSPECTION

ACTION

1
•  Inspect the cabin temperature sensor. (See CABIN TEMPERATURE SENSOR INSPECTION.)
•  Is it normal?
Yes
Go to the next step.
No
Replace the cabin temperature sensor. (See CABIN TEMPERATURE SENSOR REMOVAL/INSTALLATION .)
2
•  Disconnect the climate control unit connector and the cabin temperature sensor connector.
•  Is there an open circuit in the wiring harness between the following terminals of the climate control unit and the cabin temperature sensor?
―  Climate control unit terminal R—Cabin temperature terminal D
―  Climate control unit terminal U—Cabin temperature terminal B
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 R and cabin temperature sensor terminal D?
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 R (cabin temperature sensor input signal)
•  Is the voltage normal? (approx. 5 V)
Yes
The system is normal at present. (Clear the past malfunction from the memory.)
No