Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Test F: DTC B1255 or DTC B1257 - A/C Ambient Temperature Sensor Open Circuit or Short to Ground
2005 Ford Thunderbird V8-3.9L VIN ASECTION Test F: DTC B1255 or DTC B1257 - A/C Ambient Temperature Sensor Open Circuit or Short to Ground
PINPOINT TEST F: DTC B1255 OR DTC B1257 - A/C AMBIENT TEMPERATURE SENSOR OPEN CIRCUIT OR SHORT TO GROUND
Normal Operation
Under normal operation, the ambient air temperature sensor receives a ground from the Dual Automatic Temperature Control (DATC) module through circuit 9-FA49 (BN/WH). A 5-volt reference voltage is supplied to the ambient air temperature sensor from the DATC module through circuit 8-FA49 (WH/VT).
Possible Causes
- An open in circuit 9-FA49 (BN/WH) or 8-FA49 (WH/VT).
- A short to together in circuits 9-FA49 (BN/WH) and 8-FA49 (WH/VT).
- A short to ground in circuit 8-FA49 (WH/VT).
- Ambient air temperature sensor.
- DATC module.
F1:
F1-F3:
F3-F5:
F6:
Normal Operation
Under normal operation, the ambient air temperature sensor receives a ground from the Dual Automatic Temperature Control (DATC) module through circuit 9-FA49 (BN/WH). A 5-volt reference voltage is supplied to the ambient air temperature sensor from the DATC module through circuit 8-FA49 (WH/VT).
Possible Causes
- An open in circuit 9-FA49 (BN/WH) or 8-FA49 (WH/VT).
- A short to together in circuits 9-FA49 (BN/WH) and 8-FA49 (WH/VT).
- A short to ground in circuit 8-FA49 (WH/VT).
- Ambient air temperature sensor.
- DATC module.
RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.