Engine Controls - System/component Tests 1.6L: Diagnosis Nissan Sentra B14

INHIBITOR SWITCH SYSTEM TEST

1. Turn ignition off. Disconnect ECM harness connector. Turn ignition on. Check continuity between ECM harness connector terminal No. 22 (Green/Orange wire) and ground. Move shift lever through gears. Continuity should exist only in Park and Neutral. If continuity is not as specified, go to next step. If continuity is as specified, system is functioning properly.
2. Disconnect inhibitor switch harness connector. Connector is located on top of transaxle. Check continuity between Black wire of inhibitor switch harness connector and ground. Continuity should exist. If continuity exists, go to next step. If continuity does not exist, check for open harness and connectors. Repair as necessary.
3. Check continuity between ECM harness connector terminal No. 22 (Green/Orange wire) and inhibitor switch harness connector. Continuity should exist. If continuity exists, check inhibitor switch. See «INHIBITOR SWITCH»(ref-17816-S04368465712000122900000). Replace switch if necessary. If switch is okay, disconnect and inspect harness and connectors for pushed-out, bent, damaged or corroded terminals. Repair harness or connectors as necessary.

NEUTRAL POSITION SWITCH SYSTEM TEST

1. Turn ignition off. Disconnect neutral position switch harness connector. Connector is located on top of transaxle. Check continuity between Black wire of neutral position switch harness connector and ground. Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair open Black wire or connectors.
2. Turn ignition off. Disconnect ECM harness connector. Check continuity between ECM harness connector terminal No. 22 (Green/Orange wire) and neutral position switch harness connector. Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair open Green/Orange wire or connectors.
3. Check neutral position switch. See «NEUTRAL POSITION»(ref-17816-S02525921112000122900000) SWITCH. Replace switch if necessary. If switch is okay, disconnect and inspect harness and connector for pushed-out, bent, damaged or corroded terminals. Repair harness or connector as necessary.

POWER STEERING OIL PRESSURE SWITCH SYSTEM TEST

1. Start engine and bring to operating temperature. Measure voltage between specified ECM harness connector terminal and ground. See «POWER STEERING OIL PRESSURE SWITCH SYSTEM TEST»(ref-17816-S01121409062000122900000) table. Turn steering wheel quickly; approximately zero volts should be present. When steering wheel is not being turned, 5 volts should be present. If voltage is not as specified, go to next step. If voltage is as specified, system is functioning properly.
2. Turn ignition off. Disconnect and inspect power steering oil pressure switch harness connector for pushed-out, bent, damaged or corroded terminals. Repair connector as necessary. Check continuity between power steering oil pressure switch harness connector Black wire and ground. Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair open Black wire or connectors.
3. Check continuity between ECM harness connector terminal and power steering oil pressure switch harness connector. See «POWER STEERING OIL PRESSURE SWITCH SYSTEM TEST»(ref-17816-S01121409062000122900000) table. Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair open harness between ECM and switch.
4. Check power steering oil pressure switch. See POWER STEERING OIL PRESSURE SWITCH. Replace switch if necessary. If switch is okay, check harness and connectors for pushed-out, bent, damaged or corroded terminals. Repair harness or connectors as necessary. POWER STEERING OIL PRESSURE SWITCH SYSTEM TEST Application Terminal No. (Wire Color) Sentra 25 (Light Blue)

VALVE TIMING CONTROL (VTC) SOLENOID SYSTEM TEST

1. Turn ignition (engine) off. Disconnect VTC solenoid harness connector. VTC solenoid is located on cylinder head, right of intake manifold. Turn ignition on. Measure voltage between ground and VTC solenoid harness connector Brown wire. Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, check 10-amp fuse and harness continuity between VTC solenoid and fuse. Repair or replace as necessary.
2. Turn ignition off. Disconnect ECM harness connector. Check continuity between ECM harness connector terminal No. 114 (Yellow/Red wire) and VTC harness connector Yellow/Red wire. Continuity should exist. If continuity does not exist, repair open Yellow/Red wire or connectors.
3. If continuity exists, check VTC solenoid. See VALVE TIMING CONTROL (VTC) SOLENOID under «SOLENOIDS»(ref-17816-S15318918722000122900000). If solenoid is okay, check ECM terminals, harness, and connectors for pushed-out, bent, damaged or corroded terminals. Repair harness or connectors as necessary.

FUEL PUMP SYSTEM TEST

1. Turn ignition on. With fingers, pinch fuel feed hose at fuel filter. Fuel pressure pulsation should be felt for 5 seconds after ignition is turned on. If pulsation is not felt, go to next step. If pulsation is felt, system is functioning properly.
2. Turn ignition off. Disconnect fuel pump relay. Fuel pump relay is located in relay box. Turn ignition on. Measure voltage between ground and fuel pump relay harness connector terminals No. 1 (Black/Blue wire) and No. 3 (Black/White wire). Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, check 15-amp fuse in main fuse box. Check harness continuity between fuse and fuel pump relay. Repair or replace as necessary.
3. Turn ignition off. Disconnect fuel pump harness connector, located under rear seat. Check continuity between ground and fuel pump harness connector Black wire. Check continuity between fuel pump relay harness connector terminal No. 5 (Black/Yellow wire) and fuel pump harness connector Black/Yellow wire. Continuity should exist in both checks. If continuity exists in both checks, go to next step. If continuity does not exist, repair appropriate harness or connectors.
4. Ensure ignition is off. Disconnect ECM harness connector. ECM is located under center of instrument panel. Check continuity between ECM harness connector terminal No. 8 (Black/Pink wire) and fuel pump relay harness connector terminal No. 2 (Black/Pink wire). Continuity should exist. If continuity does not exist, check harness and connectors between ECM and relay. Repair harness and connectors as necessary.
5. If continuity exists, check fuel pump relay. See «RELAYS»(ref-17816-S12518638312000122900000) under RELAYS & SOLENOIDS. If relay is okay, check fuel pump. See «FUEL PUMP»(ref-17816-S33961453602000122900000). If fuel pump relay and fuel pump are okay, disconnect and inspect harness and connectors for pushed-out, bent, damaged or corroded terminals. Repair harness or connectors as necessary.

FUEL INJECTOR SYSTEM TEST

1. With engine running, listen for clicking sound at each injector. If clicking sound is present at each injector, system is functioning properly. If clicking sound is not present, go to next step.
2. Turn ignition off. Disconnect injector harness connector(s). Turn ignition on. Measure voltage between ground and injector harness connector Black/Red wires. Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, check 30-amp fusible link and ignition switch. If fusible link and ignition switch are okay, repair or replace harness or connectors.
3. Ensure ignition is off. Disconnect ECM harness connector. ECM is located under center of instrument panel. Check continuity between ECM harness connector terminals No. 102 (Red/Black wire), No. 104 (Green/Black wire), No. 107 (Yellow/Black wire), and No. 109 (Blue/Black wire) and corresponding fuel injector harness connector wire color. Continuity should exist.
4. If no continuity, repair or replace harness or connectors. If continuity exists, check fuel injector. See «FUEL INJECTOR»(ref-17816-S08528938292000122900000). If fuel injector is okay, check ECM terminals, harness and connector terminals for damage or corrosion. Repair or replace as necessary.

AUXILIARY AIR CONTROL (AAC) VALVE SYSTEM TEST

Faults in auxiliary air control valve system may set Code 25 or DTC P0505. If necessary, check for stored codes. See RETRIEVING CODES in the TESTS W/CODES article.

START SIGNAL SYSTEM TEST

1. Locate ECM harness connector. ECM is located under center of instrument panel (connector is on driver's side). Turn ignition switch to START position. Measure voltage between ground and ECM harness connector terminal No. 20 (Black/Yellow wire). Battery voltage should be present in START position ONLY. Zero volts should be present in any other ignition switch position. If voltage is as specified, system is functioning properly.
2. If voltage is not as specified, repair open harness or connectors between ignition switch, 7.5 amp fuse, and ECM sub-harness connector. If items are okay, check ECM terminals, harness and connectors for pushed-out, damaged, or corroded terminals. Repair or replace as necessary.

RADIATOR (COOLING) FAN CONTROL TEST

1. A fault in radiator fan control circuit may set DTC P1900. To test system, see DTC P1900 diagnostic procedures in the «TESTS W/CODES»(ref-17815) article. To test radiator fan, go to next step.
2. Start engine and warm to operating temperature. Turn A/C switch on. Turn blower fan switch on. Ensure radiator fan comes on. Turn ignition (engine) off. Turn A/C switch and fan switch off. Disconnect engine coolant temperature sensor harness connector.
3. Connect a 150-ohm resistor to engine coolant temperature sensor harness connector. Start engine and ensure radiator fan comes on. If radiator fan operates as specified, cooling fan is functioning properly. If radiator fan does not operate as specified, proceed to the «RADIATOR FAN MOTOR TEST»(ref-17816-S19472540282000122900000) and DTC P1900 diagnostic procedures in the «TESTS W/CODES»(ref-17815) article.

RADIATOR FAN MOTOR TEST

Apply battery voltage across fan motor terminals. Radiator fan motor should operate. If motor does not operate, replace motor.

FAN MOTOR OPERATION TEST

Scheme 19

See also:
• WIRING DIAGRAMS