Diagnostic Procedure For Heater Pump Circuit

WARNING: This page is about a different car, the 2012 Nissan Pathfinder. However, it is still accessible from the selected car via links, so may be relevant.

CHECK POWER SUPPLY TO HEATER PUMP
1. Disconnect heater pump connector.
2. Turn ignition switch ON.
3. Set front blower motor to maximum speed.
4. Turn temperature control dial (passenger or driver) to full hot 32°C (90°F).
5. Check voltage between heater pump harness connector E141 terminal 1 and ground.
  1 - Ground: Battery voltage
  
  Fig 1: Checking Voltage Between Heater Pump Harness Connector E141 Terminal 1 And Ground
  Courtesy of NISSAN NORTH AMERICA, INC.
  
  Is the inspection result normal?
  
  YES: GO TO 2.
  
  NO: GO TO 3.
CHECK HEATER PUMP GROUND
1. Turn ignition switch OFF.
2. Check continuity between heater pump harness connector E141 terminal 2 and ground.
  2 - Ground: Continuity should exist .
  
  Fig 2: Checking Continuity Between Heater Pump Harness Connector E141 Terminal 2 And Ground
  Courtesy of NISSAN NORTH AMERICA, INC.
  
  Is the inspection result normal?
  
  YES: Replace heater pump. Refer to "REMOVAL AND INSTALLATION ".
  
  NO: Repair harness or connector.
CHECK HEATER PUMP RELAY
1. Turn ignition switch OFF.
2. Check heater pump relay. Refer to "COMPONENT INSPECTION (VQ40DE) ".
  Is the inspection result normal?
  
  YES: GO TO 4.
  
  NO: Replace heater pump relay.
CHECK RELAY POWER SUPPLY
1. Turn ignition switch ON.
2. Check voltage between heater pump relay harness connector E144 terminals 2, 5 and ground.
  2 - Ground: Battery voltage
  
  5 - Ground: Battery voltage
  
  Is the inspection result normal?
  
  YES: GO TO 5.
  
  NO: Repair harness or connector.
  
  Fig 3: Checking Voltage Between Heater Pump Relay Harness Connector E144 Terminals 2, 5 And Ground
  Courtesy of NISSAN NORTH AMERICA, INC.
CHECK HEATER PUMP MOTOR POWER CIRCUIT
1. Turn ignition switch OFF.
2. Check continuity between heater pump relay harness connector (A) E144 terminal 3 and heater pump harness connector (B) E141 terminal 1.
  3 - 1: Continuity should exist .
3. Check continuity between heater pump relay harness connector (A) E144 terminal 3 and ground.
  3 - Ground: Continuity should not exist .
  
  Fig 4: Checking Continuity Between Harness Connector E144 Terminal 3 And Connector E141 Terminal 1
  Courtesy of NISSAN NORTH AMERICA, INC.
  
  Is the inspection result normal?
  
  YES: GO TO 6.
  
  NO: Repair harness or connector.
CHECK CIRCUIT BETWEEN HEATER PUMP RELAY AND A/C AUTO AMP.
1. Disconnect A/C auto amp. connector.
2. Check continuity between A/C auto amp. harness connector M50 (A) terminal 50 and heater pump relay harness connector E144 (B) terminal 1.
  1 - 50: Continuity should exist .
3. Check continuity between heater pump relay harness connector E144 (B) terminal 1 and ground.
  1 - Ground: Continuity should not exist .
  
  Fig 5: Checking Continuity Between A/C Auto Amp. Harness Connector M50 Terminal 50 And Heater Pump Relay Harness Connector E144 Terminal 1
  Courtesy of NISSAN NORTH AMERICA, INC.
  
  Is the inspection result normal?
  
  YES: Replace A/C auto amp. Refer to "REMOVAL AND INSTALLATION ".
  
  NO: Repair harness or connector.