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: 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: Intake Sensor Circuit Diagnostic Procedure

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: Checking Intake Sensor Circuit Between Intake Sensor And Body Ground (1 Of 2)
Courtesy of NISSAN MOTOR CO., U.S.A.

Fig 3: Checking Intake Sensor Circuit Between Intake Sensor 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 INTAKE SENSOR GROUND CIRCUIT BETWEEN INTAKE SENSOR AND AUTO AMP. (LCU)
Disconnect auto amp. (LCU) harness connector.

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

Fig 5: Checking Intake Sensor Ground Circuit Between Intake 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 INTAKE SENSOR
Refer to "INTAKE SENSOR ".

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

Fig 7: Checking Intake 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.
  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.