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: Intake sensor circuit is open or shorted. (24 or -24 is indicated on auto amp. as a result of conducting Self-Diagnosis STEP 2.)

Fig 1: Identifying Intake Sensor Connectors On Auto Amp.

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

CHECK INTAKE SENSOR CIRCUIT BETWEEN INTAKE SENSOR AND BODY GROUND
Disconnect intake sensor harness connector.

Fig 2: Intake 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 Intake Sensor Terminals & Body Ground
  Courtesy of NISSAN MOTOR CO., U.S.A.
CHECK INTAKE SENSOR GROUND CIRCUIT BETWEEN INTAKE SENSOR AND AUTO AMP. (LCU)
Disconnect auto amp. (LCU) harness connector.

Fig 4: Auto Amp. (LCU) Harness 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 Intake Sensor & Auto Amp. (LCU) Connector Terminals
  Courtesy of NISSAN MOTOR CO., U.S.A.
CHECK INTAKE SENSOR
Refer to INTAKE SENSOR CIRCUIT .

OK or NG
1. OK:
  1. Replace auto amp.
  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:
  1. Replace intake sensor.
  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.
CHECK INTAKE SENSOR CIRCUIT BETWEEN AMBIENT SENSOR AND AUTO AMP. (LCU)
Disconnect auto amp. (LCU) harness connector.

Fig 6: Auto Amp. (LCU) Harness 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.
  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) Terminals
    Courtesy of NISSAN MOTOR CO., U.S.A.
2. NG: Repair harness or connector.