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Home >> Infiniti >> 2002 >> QX4 RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 208 (Auto) >> A/C System >> Ambient Sensor Circuit >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2002 Infiniti I35. However, it is still accessible from the selected car via links, so may be relevant.

SYMPTOM: Ambient sensor circuit is open or shorted. (21 or -21 is indicated on the display as a result of conducting SELF DIAGNOSIS STEP 2.) 

Fig 1: Identifying Ambient Sensor Circuit
G02006819Courtesy of NISSAN MOTOR CO., U.S.A.
  1. CHECK VOLTAGE BETWEEN AMBIENT SENSOR HARNESS CONNECTOR AND BODY GROUND 

    Disconnect ambient sensor harness connector.

    Do approx. 5 volts exist between ambient sensor harness terminal No. 1 and body ground?

    Fig 2: Checking Voltage Between Ambient Sensor Harness Connector And Body Ground
    G02006820Courtesy of NISSAN MOTOR CO., U.S.A.

    Yes or No 

    1. Yes : GO TO 2.
    2. No : GO TO  4.
  2. CHECK AMBIENT SENSOR CIRCUIT BETWEEN AMBIENT SENSOR AND AUTO AMP. (LCU) 
    1. Disconnect auto amp. (LCU) harness connector.
    2. Check circuit continuity between ambient sensor harness terminal No. 2 and auto amp. (LCU) harness terminal No. 11.
      Fig 3: Checking Ambient Sensor Circuit Between Ambient Sensor And Auto Amp. (LCU)
      G02006821Courtesy of NISSAN MOTOR CO., U.S.A.

      Continuity should exist. 

    If OK, check harness for short.

    OK or NG 

    1. OK : GO TO 3.
    2. NG : Repair harness or connector.
  3. CHECK AMBIENT SENSOR 

    Refer to , "AMBIENT SENSOR ".

    OK or NG 

    1. OK
      1. Replace auto amp. (LCU).
      2. Go to , "FUNCTION CONFIRMATION PROCEDURE ", "Self-diagnosis", and perform SELF-DIAGNOSIS STEP 2.

        Confirm that code No. 20 is displayed.

    2. NG : Replace ambient sensor.
  4. CHECK AMBIENT SENSOR CIRCUIT BETWEEN AMBIENT SENSOR AND AUTO AMP. (LCU) 
    1. Disconnect auto amp. (LCU) harness connector.
    2. Check circuit continuity between ambient sensor harness terminal No. 1 and auto amp. (LCU) harness terminal No. 2.
      Fig 4: Checking Ambient Sensor Circuit Between Ambient Sensor And Auto Amp. (LCU)
      G02006822Courtesy of NISSAN MOTOR CO., U.S.A.

      Continuity should exist. 

    If OK, check harness for short.

    OK or NG 

    1. Yes
      1. Replace auto amp. (LCU).
      2. Go to , "FUNCTION CONFIRMATION PROCEDURE ", "Self-diagnosis", and perform SELF-DIAGNOSIS STEP 2.

        Confirm that code No. 20 is displayed.

    2. NG : Repair harness or connector.
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