Electrical Load Signal (ALTIMA, I30, Maxima, Pathfinder, QX4 & SENTRA): Sentra

Turn ignition on. Measure voltage between ground and ECM terminal No. 50 (Red/White wire) by backprobing. See Figure and Figure . With rear window defogger on, battery voltage should exist. With rear window defogger off, zero volts should exist. If voltage is as specified, go to next step. If voltage is not as specified, go to step 4.
Measure voltage between ground and ECM terminal No. 50 (Red/White wire) by backprobing. With headlights on, battery voltage should exist. With headlights off, zero volts should exist. If voltage is as specified, go to next step. If voltage is not as specified, go to step 7.
Measure voltage between ground and ECM terminal No. 51 (Light Green/Black wire) by backprobing. With blower fan on, battery voltage should exist. With blower fan off, zero volts should exist. If voltage is as specified, go to step 5. If voltage is not as specified, go to step 10.
Start engine. Turn rear window defogger on. If rear window warms up, go to next step. If rear window does not warm up, repair rear window defogger. See appropriate REAR WINDOW DEFOGGERS article in ACCESSORIES & EQUIPMENT.
Turn ignition off. Disconnect rear window defogger relay harness connector. See Figure. Disconnect ECM harness connector. Connect positive ohmmeter lead to ECM harness connector terminal No. 50 (Red/White wire) and negative ohmmeter lead to rear window defogger relay harness connector terminals No. 5 and 7 (Blue/Red wires). See Figure and Figure . Continuity should exist. Go to next step.
Connect negative ohmmeter lead to ECM harness connector terminal No. 50 (Red/White wire) and positive ohmmeter lead to rear window defogger relay harness connector terminals No. 5 and 7 (Blue/Red wires). Continuity should not exist. Also, check circuit for short to ground and short to voltage. Repair circuit or replace diode as necessary. See WIRING DIAGRAMS article. If circuit and diode are okay, go to step 13.
Start engine. Turn headlights on. If headlights illuminate, go to next step. If headlights do not illuminate, repair lighting system. See HEADLIGHT SYSTEMS article in ACCESSORIES & EQUIPMENT.
Stop engine. Turn ignition off. Disconnect headlight switch 4-pin harness connector and ECM harness connector. Connect positive ohmmeter lead to ECM harness connector terminal No. 50 (Red/White wire) and negative lead to headlight switch 4-pin harness connector terminal No. 10 (Red/Yellow wire). Continuity should exist. Go to next step.
Connect negative ohmmeter lead to ECM harness connector terminal No. 50 (Red/White wire) and positive lead to headlight switch 4-pin harness connector terminal No. 10 (Red/Yellow wire). Continuity should not exist. Also, check circuit for short to ground and short to voltage. Repair circuit or replace diode as necessary. If circuit and diode are okay, go to step 13
Start engine. Turn heater fan on. If fan motor operates, go to next step. If fan motor does not operate, repair blower motor. See appropriate MANUAL OR AUTOMATIC A/C-HEATER SYSTEMS article in AIR CONDITIONING & HEATING.
Stop engine. Disconnect heater fan control switch harness and ECM harness connectors. Check continuity of Light Green/Black wire between heater fan control switch harness connector terminal No. 6 and ECM harness connector terminal No. 51. Also, check circuit for short to ground and short to voltage. Repair circuit as necessary. If circuit is okay, go to next step.
Check continuity of Black wire between ground and heater fan control switch harness connector terminal No. 5. Continuity should exist. Also, check circuit for short to voltage. Repair circuit as necessary. See WIRING DIAGRAMS article. If circuit is okay, go to next step.
No problem is indicated at this time. Problem may be intermittent. See TESTING PROCEDURE under SELF-DIAGNOSTIC SYSTEM in appropriate SELF-DIAGNOSTICS article.