Diagnostic Procedure

WARNING: This page is about a different car, the 2003 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: Identifying Ambient Sensor Circuit

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: Checking Voltage Between Ambient Sensor Harness Connector And Body Ground (1 Of 2)
Courtesy of NISSAN MOTOR CO., U.S.A.

Fig 3: Checking Voltage Between Ambient Sensor Harness Connector And Body Ground (2 Of 2)
Courtesy of NISSAN MOTOR CO., U.S.A.

OK or NG
1. OK: GO TO 2.
2. NG: GO TO 4.
CHECK AMBIENT SENSOR GROUND CIRCUIT BETWEEN AMBIENT SENSOR AND AUTO AMP. (LCU)
Disconnect auto amp. (LCU) harness connector.

Fig 4: Checking Ambient Sensor Ground Circuit Between Ambient Sensor And Auto AMP. (LCU) (1 Of 2)
Courtesy of NISSAN MOTOR CO., U.S.A.

Fig 5: Checking Ambient Sensor Ground Circuit Between Ambient Sensor And Auto AMP. (LCU) (2 Of 2)
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.
CHECK AMBIENT SENSOR
Refer to "AMBIENT SENSOR CIRCUIT ".

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: Checking Ambient Sensor Circuit Between Ambient Sensor And Auto Amp. (LCU) (1 Of 2)
Courtesy of NISSAN MOTOR CO., U.S.A.

Fig 7: Checking Ambient Sensor Circuit Between Ambient Sensor And Auto Amp. (LCU) (2 Of 2)
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.
2. NG: Repair harness or connector.