Diagnostic Procedure

WARNING: This page is about a different car, the 2002 Nissan Altima. 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 auto amp. as a result of conducting Self-Diagnosis STEP 2.)

Fig 1: Connecting Auto Amp. Terminals

Courtesy of NISSAN MOTOR CO., U.S.A.

CHECK VOLTAGE BETWEEN AMBIENT SENSOR HARNESS CONNECTOR AND BODY GROUND
Disconnect ambient sensor harness connector.

Fig 2: Ambient Sensor Harness Connector Terminals Voltage Chart
Courtesy of NISSAN MOTOR CO., U.S.A.

OK or NG
1. OK: GO TO 2.
2. NG: GO TO 4.
  
  Fig 3: Checking Voltage Between Ambient Sensor Harness Connector & Body Ground
  Courtesy of NISSAN MOTOR CO., U.S.A.
CHECK AMBIENT SENSOR GROUND CIRCUIT BETWEEN AMBIENT SENSOR AND AUTO AMP. (LCU)
Disconnect auto amp. (LCU) harness connector.

Fig 4: Ambient Sensor And Auto Amp. (LCU) Connector Terminals Continuity Chart
Courtesy of NISSAN MOTOR CO., U.S.A.

If OK, check harness for short.

OK or NG
1. OK: GO TO 3.
2. NG: Repair harness or connector.
  
  Fig 5: Checking Continuity Between Ambient Sensor & Auto Amp (LCU) Connector Terminals
  Courtesy of NISSAN MOTOR CO., U.S.A.
CHECK AMBIENT SENSOR
Refer to AMBIENT SENSOR .

OK or NG
1. OK:
  1. Replace auto amp. (LCU).
  2. Go to SELF-DIAGNOSIS and perform self-diagnosis STEP 2. Confirm that code No. 20 is displayed.
2. NG: Replace ambient sensor.
CHECK AMBIENT SENSOR CIRCUIT BETWEEN AMBIENT SENSOR AND AUTO AMP. (LCU)
Disconnect auto amp. (LCU) harness connector.

Fig 6: Ambient Sensor & Auto Amp. (LCU) Connector Terminals Continuity Chart
Courtesy of NISSAN MOTOR CO., U.S.A.

If OK, check harness for short.

OK or NG
1. OK:
  1. Replace auto amp. (LCU).
  2. Go to self-diagnosis step-by-step procedure (Refer to SELF-DIAGNOSIS) and perform self-diagnosis STEP 2. Confirm that code No. 20 is displayed.
    
    Fig 7: Checking Continuity Between Ambient Sensor & Auto Amp (LCU) Connector Terminals
    Courtesy of NISSAN MOTOR CO., U.S.A.
2. NG: Repair harness or connector.