With Color Display

B257B, B257C AMBIENT SENSOR





Description

COMPONENT DESCRIPTION

Ambient Sensor





- The ambient sensor (1) is installed to the front bumper reinforcement.
- It detects ambient temperature and converts it into a resistance value which is then input into the A/C auto amp.

Ambient Sensor Circuit






AMBIENT TEMPERATURE INPUT PROCESS

The A/C auto amp. equips a processing circuit for the ambient sensor input. However, when the temperature detected by the ambient sensor increases quickly, the processing circuit retards the A/C auto amp. function. It only allows the A/C auto amp. to recognize an ambient temperature increase of 0.33�C (0.6�F) per 100 seconds.
As an example, consider stopping for a few minutes after high-speed driving. Although the actual ambient temperature has not changed, the temperature detected by the ambient sensor increases. This is because the heat from the engine compartment can radiate to the front bumper area, the location of the ambient sensor.




DTC Logic

DTC DETECTION LOGIC

NOTE:
- If DTC is displayed along with DTC U1000 or U1010, first diagnose the DTC U1000 or U1010. With Color Display or With Color Display.
- If there is an open circuit in the ambient sensor, A/C auto amp. registers extreme cold [-30�C (-22�F)] and adjusts the temperature control warmer.






DTC CONFIRMATION PROCEDURE
1.CHECK WITH SELF-DIAGNOSIS FUNCTION OF CONSULT-III
1. Using CONSULT-III, perform "SELF-DIAGNOSIS RESULTS" of HVAC.
2. Check if any DTC No. is displayed in the self-diagnosis results.

NOTE:
- If DTC is displayed along with DTC U1000 or U1010, first diagnose the DTC U1000 or U1010. With Color Display or With Color Display.
- If there is an open circuit in the ambient sensor, A/C auto amp. registers extreme cold [-30�C (-22�F)] and adjusts the temperature control warmer.
Is DTC No."B257B" or "B257C" displayed?
YES - Perform trouble diagnosis for the ambient sensor. With Color Display.
NO - Inspection End.



Diagnosis Procedure
Regarding Wiring Diagram information, With Navi or Without Navi.
1.CHECK VOLTAGE BETWEEN AMBIENT SENSOR AND GROUND





1. Disconnect ambient sensor connector.
2. Turn ignition switch ON.
3. Check voltage between ambient sensor harness connector E211 terminal 1 and ground.

1 - Ground : Approx. 5V

Is the inspection result normal?
YES - GO TO 2.
NO - GO TO 4.
2.CHECK CONTINUITY BETWEEN AMBIENT SENSOR AND A/C AUTO AMP.





1. Turn ignition switch OFF.
2. Disconnect A/C auto amp. connector.
3. Check continuity between ambient sensor harness connector E211 (A) terminal 2 and A/C auto amp. harness connector M37(B) terminal 37.

2 - 37 : Continuity should exist.

Is the inspection result normal?
YES - GO TO 3.
NO - Repair harness or connector.
3.CHECK AMBIENT SENSOR
Check ambient sensor. With Color Display.
Is the inspection result normal?
YES - Replace A/C auto amp. With Color Display.
NO - Replace ambient sensor. With Color Display.
4.CHECK CONTINUITY BETWEEN AMBIENT SENSOR AND A/C AUTO AMP.





1. Turn ignition switch OFF.
2. Disconnect A/C auto amp. connector.
3. Check continuity between ambient sensor harness connector E211 (A) terminal 1 and A/C auto amp. harness connector M37 (B) terminal 35.

1 - 35 : Continuity should exist.

4. Check continuity between ambient sensor harness connector E211 (A) terminal 1 and ground.

1 - Ground : Continuity should not exist.

Is the inspection result normal?
YES - Replace A/C auto amp. With Color Display.
NO - Repair harness or connector.




Component Inspection
1.CHECK AMBIENT SENSOR
1. Turn ignition switch OFF.
2. Disconnect ambient sensor connector.
3. Check resistance between ambient sensor terminals.





Is the inspection result normal?
YES - Inspection End.
NO - Replace ambient sensor. With Color Display.