Diagnostic Procedure For Heater Pump Circuit

WARNING: This page is about a different car, the 2007 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
OK or NG

OK: GO TO 2.

NG: GO TO 3.

Fig 1: Checking Voltage Between Heater Pump Harness Connector E141 Terminal 1 And Ground
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.
OK or NG

OK: Replace heater pump. Refer to "HEATER PUMP ".

NG: Repair harness or connector.

Fig 2: Checking Continuity Between Heater Pump Harness Connector E141 Terminal 2 And Ground
CHECK HEATER PUMP RELAY
1. Turn ignition switch OFF.
2. Check heater pump relay. Refer to "HEATER PUMP RELAY ".
OK or NG

OK: GO TO 4.

NG: 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
OK or NG

OK: GO TO 5.

NG: Repair harness or connector.

Fig 3: Checking Voltage Between Heater Pump Relay Harness Connector E144 Terminals 2, 5 And Ground
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 (A) E144 Terminal 3 And Connector (B) E141 Terminal 1
OK or NG

OK: GO TO 6.

NG: Repair harness or connector.
CHECK CIRCUIT BETWEEN HEATER PUMP RELAY AND FRONT AIR CONTROL
1. Disconnect front air control connector.
2. Check continuity between front air control harness connector (A) M50 terminal 44 and heater pump relay harness connector (B) E144 terminal 1.
  1 - 44 : Continuity should exist.
3. Check continuity between heater pump relay harness connector (B) E144 terminal 1 and ground.
  1 - Ground : Continuity should not exist.
  
  Fig 5: Checking Continuity Between Harness Connector (A) M50 Terminal 44 And Connector (B) E144 Terminal 1
OK or NG

OK: Replace front air control. Refer to "FRONT AIR CONTROL ".

NG: Repair harness or connector.