Diagnosis Procedure

Regarding Wiring Diagram information, refer to WIRING DIAGRAM .

1. CHECK FUSE
   
   
   1. Turn ignition switch OFF.
   2. Check 15A fuses [Nos. 17 and 27, located in fuse block (J/B)].
      NOTE:

      Refer to TERMINAL ARRANGEMENT .

   Is the inspection result normal?

   YES 

   GO TO STEP 2  .

   NO 

   Replace the blown fuse after repairing the affected circuit.

2. CHECK FRONT BLOWER MOTOR POWER SUPPLY
   
   
   1. Disconnect front blower motor connector.
   2. Turn ignition switch ON.
   3. Check voltage between front blower motor harness connector and ground.

      +		-		Voltage
      Front blower motor
      Connector	Terminal
      M112	4	Ground		Battery voltage

   Is the inspection result normal?

   YES 

   GO TO STEP 3  .

   NO 

   GO TO STEP   6  .

3. CHECK FRONT BLOWER MOTOR GROUND CIRCUIT
   
   
   1. Turn ignition switch OFF.
   2. Check continuity between front blower motor harness connector and ground.

      Front blower motor		-		Continuity
      Connector	Terminal
      M112	1	Ground		Yes

   Is the inspection result normal?

   YES 

   GO TO STEP 4  .

   NO 

   Repair harness or connector.

4. CHECK FRONT BLOWER MOTOR CONTROL SIGNAL CIRCUIT
   
   
   1. Disconnect A/C auto amp. connector.
   2. Check continuity between front blower motor harness connector and A/C auto amp. harness connector.

      Front blower motor		A/C auto amp.		Continuity
      Connector	Terminal	Connector	Terminal
      M112	3	M50	18	Yes

   Is the inspection result normal?

   YES 

   GO TO STEP 5  .

   NO 

   Repair the harness or connector.

5. CHECK FRONT BLOWER MOTOR CONTROL SIGNAL
   
   
   1. Reconnect front blower motor connector and A/C auto amp. connector.
   2. Turn ignition switch ON.
   3. Operate MODE switch to set air outlet to VENT.
   4. Change fan speed from Lo to Hi, and check duty ratios between front blower motor harness connector and ground by using an oscilloscope.
      NOTE:

      Calculate drive signal duty ratio as shown in the figure below.

      T2 = Approx. 1.6 ms

      Fig 1: PWM Signal Blinking Pattern

      Courtesy of NISSAN NORTH AMERICA, INC.

      Front blower motor		Condition	Duty ratio (Approx.)
      Connector	Terminal	Fan speed (manual) VENT mode
      M112	3	1st	25 %
      		2nd	33 %
      		3rd	41 %
      		4th	51 %
      		5th	61 %
      		6th	69 %
      		7th	81 %

   Is the inspection result normal?

   YES 

   Replace front blower motor. Refer to REMOVAL AND INSTALLATION .

   NO 

   Replace A/C auto amp. Refer to REMOVAL AND INSTALLATION .

6. CHECK FRONT BLOWER MOTOR RELAY GROUND CIRCUIT
   
   
   1. Turn ignition switch OFF.
   2. Check continuity between fuse block (J/B) harness connector and ground.

      Fuse block (J/B)		-	Continuity
      Connector	Terminal
      M68	13R	Ground	Yes

   Is the inspection result normal?

   YES 

   GO TO STEP 7  .

   NO 

   Repair harness or connector.

7. CHECK FRONT BLOWER RELAY
   
   

   Check front blower motor relay. Refer to COMPONENT INSPECTION (FRONT BLOWER MOTOR RELAY) .

   Is the inspection result normal?

   YES 

   Repair harness or connector between front blower motor and fuse block (J/B).

   NO 

   Replace front blower relay.