Test B: DTC B1255 or DTC B1257 - A/C Ambient Temperature Sensor Open Circuit or Short to Ground

PINPOINT TEST B: DTC B1255 OR DTC B1257 - A/C AMBIENT TEMPERATURE SENSOR OPEN CIRCUIT OR SHORT TO GROUND

B1-B3:

B4-B5:

B6-B7:

Normal Operation
Under normal operation, the ambient air temperature sensor receives a ground from the electronic automatic temperature control (EATC) or dual automatic temperature control (DATC) module through circuit RH104 (BU/BN). A 5-volt reference voltage is supplied to the ambient air temperature sensor from the DATC/EATC module through circuit VH407 (YE/GN).

Possible Causes
- An open in circuit RH104 (BU/BN) or VH407 (YE/GN)
- A short to voltage in circuit RH104 (BU/BN)
- A short to ground in circuit VH407 (YE/GN)
- Ambient air temperature sensor
- DATC/EATC module