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

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

C1-C3:

C3-C5:

C5-C6:

Normal Operation
Under normal operation, the ambient air temperature sensor receives a ground from the dual automatic temperature control (DATC) module through circuit 470 (PK/BK)/233 (DB/YE). A 5 volt reference voltage is supplied to the ambient air temperature sensor from the DATC module through circuit 234 (DB/WH).

Possible Causes
- An open in circuit 470 (PK/BK)/233 (DB/YE) or 234 (DB/WH).
- A short to voltage in circuit 470 (PK/BK)/233 (DB/YE).
- A short to ground in circuit 234 (DB/WH).
- Ambient air temperature sensor.
- DATC module.