DTC DETECTION LOGIC

DTC | Items (CONSULT-III screen terms) | Diagnostic item is detected when... | Possible causes
B257B | AMB TEMP SEN SHORT | The ambient sensor recognition temperature is too high. |

- Ambient sensor
- A/C auto amp.
- Harness and connector
  (Short in the ambient sensor circuit)

B257C | AMB TEMP SEN OPEN | The ambient sensor recognition temperature is too low. |

- Ambient sensor
- A/C auto amp.
- Harness and connector
  (Open in the ambient sensor circuit)

DTC CONFIRMATION PROCEDURE
1.PERFORM SELF-DIAGNOSIS
With CONSULT-III

1. Perform the “SELF-DIAGNOSIS”.
2. Check if any DTC is detected in the self-diagnostic results.

NOTE：

- If DTC is displayed along with DTC U1000 or U1010, first diagnose the DTC U1000 or U1010. Refer to DTC Logic or DTC Logic.
- If there is an open circuit in the ambient sensor, A/C auto amp registers extreme cold [−44°C (−47°F)] and adjusts the temperature control warmer.

Is DTC “B257B” or “B257C” displayed?
YES>>Perform the diagnosis for the ambient sensor. Refer to Diagnosis Procedure.
NO>>INSPECTION END