Engine Controls - System & Component Tests: Other Nissan Altima L30

Altima

1. Start engine. If engine starts, go to step 6). If engine does not start, go to next step.
2. Turn engine off and leave ignition on. Using DVOM, measure voltage between PCM harness connector terminal No. 38 (Red wire) and ground by backprobing connector. see scheme 1 If battery voltage is present, go to next step. If battery voltage is not present, repair blown fuse or open or short in Red wire between fuse block and PCM.
3. Turn ignition off. Disconnect PCM harness connector. Using DVOM, check continuity between ground and PCM harness connector terminals No. 10, 19, 39, 43, 106, 112 and 118. see scheme 1 If continuity exists on all wires, go to next step. If continuity does not exist on any wire, repair open in appropriate wire. See WIRING DIAGRAMS article.
4. Disconnect ECCS relay (located next to PCM). Turn ignition on. Using DVOM, measure voltage between ground and ECCS relay harness connector terminals No. 1 and 3. (Scheme 43) If battery voltage exists, go to next step. If battery voltage does not exist, repair blown fuse or open or short in appropriate wire.
5. Turn ignition off. Check continuity between PCM harness connector terminal No. 4 and ECCS relay harness connector terminal No. 2 (White/Green wire). see scheme 1& (Scheme 43). If continuity exists, go to next step. If continuity does not exist, repair open or short in White/Green wire.
6. Turn ignition on. Using DVOM, measure voltage between ground and PCM harness connector terminals No. 70 and 113 (White/Blue wire) by backprobing connector. If battery voltage is present, go to next step. If battery voltage is not present, repair blown fuse or open or short in White/Blue wire between fuse block and PCM.
7. Turn ignition off. While turning ignition on then off, measure voltage between ground and PCM harness connector terminals No. 56 and 61 by backprobing connector. Battery voltage should exist with ignition on and for a few seconds after ignition is turned off. If voltage is as specified, go to step 13). If battery voltage does not exist, go to next step. If battery voltage exists for more than a few seconds after ignition is turned off, go to step 12).
8. Turn ignition off. Disconnect PCM harness connector. Disconnect ECCS relay (located under PCM). Using DVOM, check continuity between ECCS harness connector terminal No. 5 and PCM harness connector terminals No. 56 and 61. see scheme 1& (Scheme 43). If continuity exists on both wires, go to next step. If continuity does not exist on either wire, repair open or short in appropriate wire. See WIRING DIAGRAMS article.
9. Turn ignition on. Using DVOM, measure voltage between ground and ECCS relay harness connector terminals No. 1 and 3. (Scheme 43) If battery voltage exists, go to next step. If battery voltage does not exist, repair blown fuse or open or short in appropriate wire.
10. Turn ignition off. Check continuity between PCM harness connector terminal No. 4 and ECCS relay harness connector terminal No. 2. see scheme 1& (Scheme 43). If continuity exists, go to next step. If continuity does not exist, repair open or short in White/Green wire.
11. Using DVOM, check continuity between PCM harness connector terminal No. 113 and ECCS relay harness connector terminals No. 1 and 3. If continuity exists, go to next step. If continuity does not exist, repair open or short in appropriate wire. See WIRING DIAGRAMS article.
12. Check ECCS relay. See «RELAYS»(ref-18079-S17347767842000122900000) under RELAYS & SOLENOIDS. If continuity is as specified, go to next step. If continuity is not as specified, replace ECCS relay and retest system.
13. Turn ignition off. Disconnect PCM harness connector. Using DVOM, check continuity between ground and PCM harness connector terminals No. 10, 19, 39, 43, 106, 112 and 118. see scheme 1 If continuity exists on all wires, go to next step. If continuity does not exist on any wire, repair open in appropriate wire. See WIRING DIAGRAMS article.
14. Check PCM harness connector terminals for damage or corrosion. Repair as necessary, reconnect all connectors and retest system.

Scheme 43

Frontier

1. Start engine. If engine starts, go to step 6). If engine does not start, go to next step.
2. Turn engine off and leave ignition on. Using DVOM, measure voltage between PCM harness connector terminal No. 24 (White/Green wire) and ground by backprobing connector. see scheme 2 If battery voltage is present, go to next step. If battery voltage is not present, repair blown fuse or open or short in White/Green wire between fuse block and PCM.
3. Turn ignition off. Disconnect PCM harness connector. Using DVOM, check continuity between ground and PCM harness connector terminals No. 10, 19, 25, 32, 116 and 124. see scheme 2 If continuity exists on all wires, go to next step. If continuity does not exist on any wire, repair open in appropriate wire. See WIRING DIAGRAMS article.
4. Disconnect ECCS relay (located next to PCM). Turn ignition on. Using DVOM, measure voltage between ground and ECCS relay harness connector terminals No. 2 and 5. (Scheme 43) If battery voltage exists, go to next step. If battery voltage does not exist, repair blown fuse or open or short in appropriate wire.
5. Turn ignition off. Check continuity between PCM harness connector terminal No. 4 and ECCS relay harness connector terminal No. 1 (Light Green/Red wire). see scheme 1& (Scheme 43). If continuity exists, go to step 13). If continuity does not exist, repair open or short in Light Green/Red wire.
6. Turn ignition on. Using DVOM, measure voltage between ground and PCM harness connector terminal No. 80 (Light Blue wire) by backprobing connector. If battery voltage is present, go to next step. If battery voltage is not present, repair blown fuse or open or short in Light Blue wire between fuse block and PCM.
7. Turn ignition off. While turning ignition on then off, measure voltage between ground and PCM harness connector terminals No. 67, 72 and 117 by backprobing connector. Battery voltage should exist with ignition on and for a few seconds after ignition is turned off. If voltage is as specified, go to step 12). If battery voltage does not exist, go to next step. If battery voltage exists for more than a few seconds after ignition is turned off, go to step 11).
8. Turn ignition off. Disconnect PCM harness connector. Disconnect ECCS relay (located next to PCM). Using DVOM, check continuity between ECCS harness connector terminal No. 3 and PCM harness connector terminals No. 67, 72 and 117. see scheme 1& (Scheme 43). If continuity exists on both wires, go to next step. If continuity does not exist on either wire, repair open or short in appropriate wire. See WIRING DIAGRAMS article.
9. Turn ignition on. Using DVOM, measure voltage between ground and ECCS relay harness connector terminals No. 2 and 5. (Scheme 43) If battery voltage exists, go to next step. If battery voltage does not exist, repair blown fuse or open or short in appropriate wire.
10. Turn ignition off. Check continuity between PCM harness connector terminal No. 4 and ECCS relay harness connector terminal No. 1 (Light Green/Red wire). see scheme 1& (Scheme 43). If continuity exists, go to next step. If continuity does not exist, repair open or short in Light Green/Red wire.
11. Check ECCS relay. See «RELAYS»(ref-18079-S17347767842000122900000) under RELAYS & SOLENOIDS. If continuity is as specified, go to next step. If continuity is not as specified, replace ECCS relay and retest system.
12. Turn ignition off. Disconnect PCM harness connector. Using DVOM, check continuity between ground and PCM harness connector terminals No. 10, 19, 25, 32, 116 and 124. see scheme 2 If continuity exists on all wires, go to next step. If continuity does not exist on any wire, repair open in appropriate wire. See WIRING DIAGRAMS article.
13. Check PCM harness connector terminals for damage or corrosion. Repair as necessary, reconnect all connectors and retest system.

Maxima

1. Start engine. If engine starts, go to step 8). If engine does not start, go to next step.
2. Turn engine off and leave ignition on. Using DVOM, measure voltage between PCM harness connector terminal No. 80 (White wire) and ground by backprobing connector. see scheme 2 If battery voltage is present, go to next step. If battery voltage is not present, repair blown fuse or open or short in White wire between fuse block and PCM.
3. Turn ignition off. While turning ignition on then off, measure voltage between ground and PCM harness connector terminals No. 67 and 72 by backprobing connector. Battery voltage should exist with ignition on and for a few seconds after ignition is turned off. If voltage is as specified, go to step 8). If battery voltage does not exist, go to next step. If battery voltage exists for more than a few seconds after ignition is turned off, go to step 7).
4. Turn ignition off. Disconnect PCM harness connector. Disconnect ECCS relay. (Scheme 44) Using DVOM, check continuity between ECCS harness connector terminal No. 5 and PCM harness connector terminals No. 67 and 72. see scheme 2and (Scheme 43). If continuity exists on both wires, go to next step. If continuity does not exist on either wire, repair open or short in appropriate wire. See WIRING DIAGRAMS article.
5. Turn ignition on. Using DVOM, measure voltage between ground and ECCS relay harness connector terminals No. 2 and 3. (Scheme 43) If battery voltage exists at both terminals, go to next step. If battery voltage does not exist at either terminal, repair blown fuse or open or short in appropriate wire.
6. Turn ignition off. Check continuity between PCM harness connector terminal No. 4 and ECCS relay harness connector terminal No. 1 (White/Black wire). If continuity exists, go to next step. If continuity does not exist, repair open or short in White/Black wire.
7. Check ECCS relay. See «RELAYS»(ref-18079-S17347767842000122900000) under RELAYS & SOLENOIDS. If continuity is as specified, go to next step. If continuity is not as specified, replace ECCS relay and retest system.
8. Turn ignition off. Disconnect PCM harness connector. Using DVOM, check continuity between ground and PCM harness connector terminals No. 10, 19, 25, 32, 108, 116 and 124. If continuity exists on all wires, go to next step. If continuity does not exist on any wire, repair open in appropriate wire. See WIRING DIAGRAMS article.
9. Check PCM harness connector terminals for damage or corrosion. Repair as necessary, reconnect all connectors and retest system.

Scheme 44

Quest

1. Start engine. If engine starts, go to step 8). If engine does not start, go to next step.
2. Turn engine off and leave ignition on. Using DVOM, measure voltage between PCM harness connector terminal No. 70 (Yellow wire) and ground by backprobing connector. see scheme 1 If battery voltage is present, go to next step. If battery voltage is not present, repair blown fuse or open or short in Yellow wire between fuse block and PCM.
3. Turn ignition off. While turning ignition on then off, measure voltage between ground and PCM harness connector terminals No. 56, 61 and 113 by backprobing connector. Battery voltage should exist with ignition on and for a few seconds after ignition is turned off. If voltage is as specified, go to step 8). If battery voltage does not exist, go to next step. If battery voltage exists for more than a few seconds after ignition is turned off, go to step 7).
4. Turn ignition off. Disconnect PCM harness connector. Disconnect ECCS relay (located on top of PCM). Using DVOM, check continuity between ECCS harness connector terminal No. 5 and PCM harness connector terminals No. 56, 61 and 113. see scheme 1& (Scheme 43). If continuity exists on all wires, go to next step. If continuity does not exist on any wire, repair open or short in appropriate wire. See WIRING DIAGRAMS article.
5. Turn ignition on. Using DVOM, measure voltage between ground and ECCS relay harness connector terminals No. 2 and 3. (Scheme 43) If battery voltage exists, go to next step. If battery voltage does not exist, repair blown fuse or open or short in appropriate wire.
6. Turn ignition off. Check continuity between PCM harness connector terminal No. 4 and ECCS relay harness connector terminal No. 1. If continuity exists, go to next step. If continuity does not exist, repair open or short in White/Green wire.
7. Check ECCS relay. See «RELAYS»(ref-18079-S17347767842000122900000) under RELAYS & SOLENOIDS. If continuity is as specified, go to next step. If continuity is not as specified, replace ECCS relay and retest system.
8. Turn ignition off. Disconnect PCM harness connector. Using DVOM, check continuity between ground and PCM harness connector terminals No. 10, 19, 39, 43, 106, 112 and 118. If continuity exists on all wires, go to next step. If continuity does not exist on any wire, repair open in appropriate wire. See WIRING DIAGRAMS article.
9. Check PCM harness connector terminals for damage or corrosion. Repair as necessary, reconnect all connectors and retest system.

Pathfinder & QX4

1. Start engine. If engine starts, go to step 6). If engine does not start, go to next step.
2. Turn engine off and leave ignition on. Using DVOM, measure voltage between PCM harness connector terminal No. 24 (Black/White wire) and ground by backprobing connector. see scheme 2 If battery voltage is present, go to next step. If battery voltage is not present, repair blown fuse or open or short in Black/White wire between fuse block and PCM.
3. Turn ignition off. Disconnect PCM harness connector. Using DVOM, check continuity between ground and PCM harness connector terminals No. 10, 19, 25, 32, 116 and 124. see scheme 2 If continuity exists on all wires, go to next step. If continuity does not exist on any wire, repair open in appropriate wire. See WIRING DIAGRAMS article.
4. Disconnect ECCS relay. (Scheme 45) Turn ignition on. Using DVOM, measure voltage between ground and ECCS relay harness connector terminals No. 1 and 7. (Scheme 46) If battery voltage exists, go to next step. If battery voltage does not exist, repair blown fuse or open or short in appropriate wire.
5. Turn ignition off. Check continuity between PCM harness connector terminal No. 4 and ECCS relay harness connector terminal No. 2 (Blue/Black wire). see scheme 2& (Scheme 46). If continuity exists, go to step 13). If continuity does not exist, repair open or short in Blue/Black wire.
6. Turn ignition on. Using DVOM, measure voltage between ground and PCM harness connector terminal No. 80 (White/Red wire) by backprobing connector. If battery voltage is present, go to next step. If battery voltage is not present, repair blown fuse or open or short in White/Red wire between fuse block and PCM.
7. Turn ignition off. While turning ignition on then off, measure voltage between ground and PCM harness connector terminals No. 67, 72 and 117 by backprobing connector. Battery voltage should exist with ignition on and for a few seconds after ignition is turned off. If voltage is as specified, go to step 12). If battery voltage does not exist, go to next step. If battery voltage exists for more than a few seconds after ignition is turned off, go to step 11).
8. Turn ignition off. Disconnect PCM harness connector. Disconnect ECCS relay. (Scheme 45) Using DVOM, check continuity between ECCS harness connector terminal No. 6 and PCM harness connector terminals No. 67, 72 and 117. see scheme 2& (Scheme 46). If continuity exists on all wires, go to next step. If continuity does not exist on any wire, repair open or short in appropriate wire. See WIRING DIAGRAMS article.
9. Turn ignition on. Using DVOM, measure voltage between ground and ECCS relay harness connector terminals No. 1 and 7. (Scheme 46) If battery voltage exists, go to next step. If battery voltage does not exist, repair or replace blown fuse or open or short in appropriate wire.
10. Turn ignition off. Check continuity between PCM harness connector terminal No. 4 and ECCS relay harness connector terminal No. 2 (Blue/Black wire). see scheme 2& (Scheme 46). If continuity exists, go to next step. If continuity does not exist, repair open or short in Blue/Black wire.
11. Check ECCS relay. See «RELAYS»(ref-18079-S17347767842000122900000) under RELAYS & SOLENOIDS. If continuity is as specified, go to next step. If continuity is not as specified, replace ECCS relay and retest system.
12. Turn ignition off. Disconnect PCM harness connector. Using DVOM, check continuity between ground and PCM harness connector terminals No. 10, 19, 25, 32, 116 and 124. see scheme 2 If continuity exists on all wires, go to next step. If continuity does not exist on any wire, repair open in appropriate wire. See WIRING DIAGRAMS article.
13. Check PCM harness connector terminals for damage or corrosion. Repair as necessary, reconnect all connectors and retest system.

Scheme 45

Scheme 46

Sentra & 200SX

1. Start engine. If engine starts, go to step 6). If engine does not start, go to next step.
2. Turn engine off and leave ignition on. Using DVOM, measure voltage between PCM harness connector terminal No. 38 (Black/Red wire) and ground by backprobing connector. see scheme 1 If battery voltage is present, go to next step. If battery voltage is not present, repair blown fuse or open or short in Black/Red wire between fuse block and PCM.
3. Turn ignition off. Disconnect PCM harness connector. Using DVOM, check continuity between ground and PCM harness connector terminals No. 10, 19, 39, 43, 106, 112 and 118. see scheme 1 If continuity exists on all wires, go to next step. If continuity does not exist on any wire, repair open in appropriate wire. See WIRING DIAGRAMS article.
4. Disconnect ECCS relay (located under PCM). Turn ignition on. Using DVOM, measure voltage between ground and ECCS relay harness connector terminals No. 1 and 3. (Scheme 43) If battery voltage exists, go to next step. If battery voltage does not exist, repair blown fuse or open or short in appropriate wire.
5. Turn ignition off. Check continuity between PCM harness connector terminal No. 4 and ECCS relay harness connector terminal No. 2. see scheme 1& (Scheme 43). If continuity exists, go to next step. If continuity does not exist, repair open or short in White/Green wire.
6. Turn ignition on. Using DVOM, measure voltage between PCM harness connector terminal No. 70 (White/Blue wire) and ground by backprobing connector. If battery voltage is present, go to next step. If battery voltage is not present, repair blown fuse or open or short in White/Blue wire between fuse block and PCM.
7. Turn ignition off. While turning ignition on then off, measure voltage between ground and PCM harness connector terminals No. 56 and 61 by backprobing connector. Battery voltage should exist with ignition on and for a few seconds after ignition is turned off. If voltage is as specified, go to step 12). If battery voltage does not exist, go to next step. If battery voltage exists for more than a few seconds after ignition is turned off, go to step 11).
8. Turn ignition off. Disconnect PCM harness connector. Disconnect ECCS relay (located under PCM). Using DVOM, check continuity between ECCS harness connector terminal No. 5 and PCM harness connector terminals No. 56 and 61. see scheme 1& (Scheme 43). If continuity exists on both wires, go to next step. If continuity does not exist on either wire, repair open or short in appropriate wire. See WIRING DIAGRAMS article.
9. Turn ignition on. Using DVOM, measure voltage between ground and ECCS relay harness connector terminals No. 1 and 3. (Scheme 43) If battery voltage exists, go to next step. If battery voltage does not exist, repair blown fuse or open or short in appropriate wire.
10. Turn ignition off. Check continuity between PCM harness connector terminal No. 4 and ECCS relay harness connector terminal No. 2. see scheme 1& (Scheme 43). If continuity exists, go to next step. If continuity does not exist, repair open or short in White/Green wire.
11. Check ECCS relay. See «RELAYS»(ref-18079-S17347767842000122900000) under RELAYS & SOLENOIDS. If continuity is as specified, go to next step. If continuity is not as specified, replace ECCS relay and retest system.
12. Turn ignition off. Disconnect PCM harness connector. Using DVOM, check continuity between ground and PCM harness connector terminals No. 10, 19, 39, 43, 106, 112 and 118. see scheme 1 If continuity exists on all wires, go to next step. If continuity does not exist on any wire, repair open in appropriate wire. See WIRING DIAGRAMS article.
13. Check PCM harness connector terminals for damage or corrosion. Repair as necessary, reconnect all connectors and retest system.

240SX

1. Start engine. If engine starts, go to step 6). If engine does not start, go to next step.
2. Turn engine off and leave ignition on. Using DVOM, measure voltage between PCM harness connector terminal No. 38 (Black/Red wire) and ground by backprobing connector. see scheme 1 If battery voltage is present, go to next step. If battery voltage is not present, repair blown fuse or open or short in Black/Red wire between fuse block and PCM.
3. Turn ignition off. Disconnect PCM harness connector. Using DVOM, check continuity between ground and PCM harness connector terminals No. 10, 19, 39, 43, 106, 112 and 118. see scheme 1 If continuity exists on all wires, go to next step. If continuity does not exist on any wire, repair open in appropriate wire. See WIRING DIAGRAMS article.
4. Disconnect ECCS relay (located behind PCM). Turn ignition on. Using DVOM, measure voltage between ground and ECCS relay harness connector terminals No. 2 and 5. (Scheme 43) If battery voltage exists, go to next step. If battery voltage does not exist, repair blown fuse or open or short in appropriate wire.
5. Turn ignition off. Check continuity between PCM harness connector terminal No. 4 and ECCS relay harness connector terminal No. 1 (Red/Black wire). see scheme 1& (Scheme 43). If continuity exists, go to next step. If continuity does not exist, repair open or short in Red/Black wire.
6. Turn ignition on. Using DVOM, measure voltage between ground and PCM harness connector terminals No. 70 and 113 (Red wire) by backprobing connector. If battery voltage is present, go to next step. If battery voltage is not present, repair blown fuse or open or short in appropriate Red wire between fuse block and PCM.
7. Turn ignition off. While turning ignition on then off, measure voltage between ground and PCM harness connector terminals No. 56 and 61 by backprobing connector. Battery voltage should exist with ignition on and for a few seconds after ignition is turned off. If voltage is as specified, go to step 12). If battery voltage does not exist, go to next step. If battery voltage exists for more than a few seconds after ignition is turned off, go to step 11).
8. Turn ignition off. Disconnect PCM harness connector. Disconnect ECCS relay (located under PCM). Using DVOM, check continuity between ECCS harness connector terminal No. 3 and PCM harness connector terminals No. 56 and 61. see scheme 1& (Scheme 43). If continuity exists on both wires, go to next step. If continuity does not exist on either wire, repair open or short in appropriate wire. See WIRING DIAGRAMS article.
9. Turn ignition on. Using DVOM, measure voltage between ground and ECCS relay harness connector terminals No. 2 and 5. (Scheme 43) If battery voltage exists, go to next step. If battery voltage does not exist, repair blown fuse or open or short in appropriate wire.
10. Turn ignition off. Check continuity between PCM harness connector terminal No. 4 and ECCS relay harness connector terminal No. 1. see scheme 1& (Scheme 43). If continuity exists, go to next step. If continuity does not exist, repair open or short in Red/Black wire.
11. Check ECCS relay. See «RELAYS»(ref-18079-S17347767842000122900000) under RELAYS & SOLENOIDS. If continuity is as specified, go to next step. If continuity is not as specified, replace ECCS relay and retest system.
12. Turn ignition off. Disconnect PCM harness connector. Using DVOM, check continuity between ground and PCM harness connector terminals No. 10, 19, 39, 43, 106, 112 and 118. see scheme 1 If continuity exists on all wires, go to next step. If continuity does not exist on any wire, repair open in appropriate wire. See WIRING DIAGRAMS article.
13. Check PCM harness connector terminals for damage or corrosion. Repair as necessary, reconnect all connectors and retest system.

ENGINE SENSORS & SWITCHES

Note. For PCM connector terminal identification, see PIN VOLTAGE CHART S article and

L - WIRING DIAGRAMS article.

CAMSHAFT POSITION SENSOR

Faults in camshaft position sensor circuit should set Diagnostic Trouble Code (DTC) P0340. To test system, see DTC P0340: CAMSHAFT POSITION (CMP) SENSOR procedures in TESTS W/CODES article.

CLOSED THROTTLE POSITION SWITCH

Faults in closed throttle position switch or circuit should set Diagnostic Trouble Code (DTC) P0510. To test system, see DTC P0510: CLOSED THROTTLE POSITION SWITCH procedures in TESTS W/CODES article.

INHIBITOR SWITCH

Faults in the inhibitor switch should set Diagnostic Trouble Code (DTC) P1706. For testing procedure, refer to DTC P1706: PARK/NEUTRAL POSITION SWITCH procedures in TESTS W/CODES article.

KNOCK SENSOR

Faults in knock sensor or circuit should set a Diagnostic Trouble Code (DTC) P0325. For testing procedure, refer to DTC P0325: KNOCK SENSOR in TESTS W/CODES article.

ENGINE COOLANT TEMPERATURE (ECT) SENSOR

Faults in engine (coolant) temperature sensor circuit should set Diagnostic Trouble Code (DTC) P0115, or DTC P0125. To test system, see DTC P0115 OR P0125: ENGINE COOLANT TEMPERATURE (ECT) SENSOR in TESTS W/CODES article.

EGR TEMPERATURE SENSOR

Faults in exhaust gas temperature sensor circuit should set DTC P1401. To test system, see DTC P1401: EGR TEMPERATURE SENSOR diagnostic procedures in TESTS W/CODES article.

EVAP PRESSURE SENSOR

Faults in EVAP pressure sensor circuit should set DTC P0450. To test system, see DTC P0450: EVAP CONTROL SYSTEM PRESSURE SENSOR diagnostic procedures in TESTS W/CODES article.

FUEL TEMPERATURE SENSOR

Faults in fuel temperature sensor or circuit should set DTC P0180. To test system, see DTC P0180: TANK FUEL TEMPERATURE (TFT) SENSOR diagnostic procedures in TESTS W/CODES article.

INTAKE AIR TEMPERATURE (IAT) SENSOR

Faults in IAT sensor or circuit should set a Diagnostic Trouble Code (DTC) P0110. For testing procedure, refer to DTC P0110: INTAKE AIR TEMPERATURE (IAT) SENSOR in TESTS W/CODES article.

Except Maxima, Pathfinder & QX4

Faults in oxygen sensor circuit should set DTC P0130 - P0135 (front) or DTC P0137 - P0141 (rear). To test system, see procedures in TESTS W/CODES article.

Faults in oxygen sensor circuit should set DTC P0150 - P0155 (left front), DTC P0130 - P0135 (right front), or DTC P0137 - P0141 (rear). To test system, see diagnostic procedures in TESTS W/CODES article.

Faults in oxygen sensor circuit should set DTC P0150 - P0155 (left front), DTC P0130 - P0135 (right front), DTC P0157 - P0161 (right rear) or DTC P0137 - P0141 (left rear). To test system, see diagnostic procedures in TESTS W/CODES article.

MASS AIRFLOW SENSOR

Faults in mass airflow sensor circuit should set Diagnostic Trouble Code (DTC) P0100. For testing procedure, refer to DTC P0100: MASS AIRFLOW (MAF) SENSOR in TESTS W/CODES article.

NEUTRAL POSITION SWITCH

Faults in neutral position switch circuit should DTC P1706. To test system, see DTC P1706: PARK/NEUTRAL POSITION SWITCH diagnostic procedures in TESTS W/CODES article.

POWER STEERING OIL PRESSURE SWITCH

Disconnect power steering oil pressure switch connector. Switch is attached to power steering high pressure hose. Start engine. Using DVOM, check continuity between power steering oil pressure switch terminals (on models with 2-pin connector) or between power steering oil pressure switch terminal (on models with 1-pin connector) and ground. See POWER STEERING OIL PRESSURE SWITCH SPECIFICATIONS table. Replace switch if continuity is not as specified.

POWER STEERING OIL PRESSURE SWITCH SPECIFICATIONS

Altima, Frontier, Quest, Sentra, 200SX & 240SX

1. Start engine. Using DVOM, measure voltage between PCM harness connector terminal No. 25 and ground by backprobing connector. see scheme 1 Turn steering wheel quickly; approximately zero volts should be present. When steering wheel is not being turned, 5 volts should be present. On Quest, Sentra (2.0L), 200SX (2.0L) and 240SX, if voltage is not as specified, go to next step. On Altima, Frontier, Sentra (1.6L) and 200SX (1.6L), if voltage is not as specified, go to step 3). On all models, 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 (Brown wire on Quest) and ground. Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair open in Black or Brown wire.
3. Turn ignition off. Disconnect PCM harness connector. Check continuity between PCM harness connector terminal No. 25 (terminal No. 39 on Frontier) and power steering oil pressure switch harness connector terminal. See «POWER STEERING OIL PRESSURE SWITCH CIRCUIT IDENTIFICATION»(ref-18079-S07857109152000122900000) table. Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair open in appropriate wire between PCM 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 CIRCUIT IDENTIFICATION

1. Start engine. Measure voltage between PCM harness connector terminal No. 39 (Green wire) and ground. Turn steering wheel quickly; approximately zero volts should be present. When steering wheel is not being turned, battery voltage should be present. If voltage is not as specified, go to next step. If voltage is as specified, system is functioning properly.
2. Stop engine. Disconnect Idle Air Control (IAC)-FICD valve. Turn ignition on. Check voltage between ground and IAC valve terminal No. 1 (Red/Yellow wire). Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, repair or replace 10-amp fuse, Red/Yellow wire and/or harness connectors between IAC-FICD valve and fuse.
3. Turn ignition off. Disconnect power steering oil pressure switch harness connector. Check continuity between IAC valve terminal No. 2 (Green wire) and power steering oil pressure switch harness connector terminal No. 1. Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair open in Green wire.
4. Check continuity between power steering pressure switch harness connector terminal No. 2 (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.
5. Disconnect PCM harness connector. Check continuity between PCM harness connector terminal No. 39 (Green wire) and power steering oil pressure switch harness connector terminal No. 1. Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair open Green wire or connectors.
6. Check power steering pressure switch. See «POWER STEERING OIL PRESSURE SWITCH»(ref-18079-S18245885042000122900000) . Replace switch if necessary. If switch is okay, check PCM, IAC-FICD valve and pressure switch harness connectors for pushed-out, bent, damaged or corroded terminals. Repair harness or connectors as necessary.

1. Start engine and bring to operating temperature. Measure voltage between ground and PCM harness connector terminal No. 39 (Red/Black wire). Turn steering wheel quickly; approximately 0 volt should be present. When steering wheel is not being turned, approximately 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 power steering oil pressure switch harness connector. Check continuity between power steering pressure switch harness connector terminal No. 1 (Black wire) and ground. Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair open in Black wire or connector.
3. Disconnect PCM harness connector. Check continuity between PCM harness connector terminal No. 39 (Red/Black wire) and power steering pressure switch harness connector terminal No. 2. Continuity should exist. If continuity does not exist, repair open in Red/Black wire.
4. If continuity exists, check power steering oil pressure switch. See «POWER STEERING OIL PRESSURE SWITCH»(ref-18079-S18245885042000122900000) . 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.

THROTTLE POSITION (TP) SENSOR

Faults in TP sensor circuit should set DTC P0120. To test system, see DTC P0120: THROTTLE POSITION (TP) SENSOR diagnostic procedures in TESTS W/CODES article.

VEHICLE SPEED SENSOR

Faults in vehicle speed sensor circuit should set DTC P0500. To test system, see DTC P0500: VEHICLE SPEED SENSOR (VSS) diagnostic procedures in TESTS W/CODES article.

RELAYS

The following relays can be tested using an ohmmeter and remotely supplied power and ground circuits

1. Powertrain Control Module (PCM or ECCS) relay.
2. Fuel pump relay.
3. Radiator (cooling) fan relay.
4. Park/neutral position (inhibitor) relay.

ECCS & Fuel Pump Relays

1. Two types of relays are used; 4-terminal and 6-terminal. On all relays, apply battery voltage and ground to terminals No. 1 and 2. (Scheme 47)or (Scheme 48).
2. On 4-terminal relays, continuity should exist between terminals No. 3 and 5. On 6-terminal relays, continuity should exist between terminals No. 3, 5, 6 and 7. When battery voltage is removed, continuity should not exist. Replace relay if test values are not as specified.

Park/Neutral Position (Inhibitor) Relay

For testing procedure, refer to DTC P0705: PARK/NEUTRAL POSITION SWITCH procedures in TESTS W/CODES article.

Radiator (Cooling) Fan Relay

For testing procedure, refer to MIL 0208: RADIATOR (COOLING) FAN CONTROL procedures in TESTS W/CODES article.

Scheme 47

Scheme 48

EGR Control (EGRC) Solenoid

For testing procedure, refer to DTC P1400: EGR CONTROL (EGRC) SOLENOID procedures in TESTS W/CODES article.

EVAP Canister Purge Control Solenoid

For testing procedure, refer to DTC P1492: EVAP CANISTER PURGE CONTROL SOLENOID procedures in TESTS W/CODES article.

EVAP Canister Purge Volume Control Solenoid

For testing procedure, refer to DTC P0443 OR P1444: EVAP CANISTER PURGE VOLUME CONTROL SOLENOID procedures in TESTS W/CODES article.

EVAP Canister Vent Control Solenoid

For testing procedure, refer to DTC P0446, P1446 OR P1448: EVAP CANISTER VENT CONTROL SOLENOID procedures in TESTS W/CODES article.

MAP/BARO Solenoid

For testing procedure, refer to DTC P1105: MANIFOLD ABSOLUTE PRESSURE (MAP)/BAROMETRIC PRESSURE (BARO) SOLENOID procedures in TESTS W/CODES article.

Fast Idle Control Device (FICD) Solenoid

See FAST IDLE CONTROL DEVICE (FICD) SOLENOID under IDLE CONTROL SYSTEMS.

Valve Timing Control (VTC) Solenoid (Sentra 1.6L)

VTC solenoid is located on cylinder head, right of intake manifold. To test solenoid, apply battery voltage across solenoid terminals. Replace solenoid if it does not operate. To test Valve Timing Control (VTC) solenoid system, go to VALVE TIMING CONTROL (VTC) SOLENOID SYSTEM TEST.

Sentra (1.6L)

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 PCM harness connector. Check continuity between PCM 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»(ref-18079-S08143520532000122900000) (SENTRA 1.6L) under SOLENOIDS. If solenoid is okay, check PCM terminals, harness, and connectors for pushed-out, bent, damaged or corroded terminals. Repair harness or connectors as necessary.

FUEL DELIVERY

Note. For fuel system pressure testing, see FUEL PRESSURE under FUEL SYSTEM in BASIC TESTING article. If PCM receives incorrect start (cranking) signal, fuel delivery system may not operate properly. See START SIGNAL under IGNITION SYSTEMS.

Fuel Pressure Regulator

Connect fuel pressure gauge to fuel line before regulator, leaving fuel lines connected. Disconnect vacuum hose from fuel pressure regulator. Plug hose end. Connect hand-held vacuum pump to fuel pressure regulator. Start engine. Gradually apply vacuum to fuel pressure regulator. Compare fuel pressure to regulated pressure in FUEL PRESSURE table in BASIC TESTING article. If pressure is not as specified, replace fuel pressure regulator.

FUEL PUMP

To test fuel pump, disconnect fuel pump connector, accessible through trunk (Maxima and 240SX), under rear seat (Altima, Sentra and 200SX), or under vehicle body (Pathfinder, QX4, Frontier and Quest). At fuel pump connector, check resistance between fuel pump terminals specified in FUEL PUMP RESISTANCE TEST table. If resistance is not as specified, replace fuel pump.

FUEL PUMP RESISTANCE 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 harness connector. Fuel pump relay is left-hand relay located in fuse panel above datalink connector. 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 fuse in main fuse box. Check appropriate wire 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 circuits, go to next step. If continuity does not exist in either circuit, repair appropriate harness or connectors.
4. Ensure ignition is off. Disconnect PCM harness connector. see scheme 1 PCM is located under center of instrument panel (connector is on passenger's side). Check continuity between PCM 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 exists, go to next step. If continuity does not exist, repair open or short Black/Pink wire between PCM and fuel pump relay harness connectors. Repair harness and connectors as necessary.
5. Check fuel pump relay. See «RELAYS»(ref-18079-S17347767842000122900000) under RELAYS & SOLENOIDS. If relay is okay, check fuel pump. See FUEL PUMP. If fuel pump relay and fuel pump are okay, check circuit harness connector terminals for pushed-out, bent, damaged or corroded terminals. Repair harness or connectors as necessary.

1. Turn ignition on. Listen for fuel pump operating sound. Fuel pump should operate for 5 seconds after ignition is turned on. If operating sound is not heard, go to next step. If operating sound is heard, system is functioning properly.
2. Turn ignition off. Disconnect fuel pump relay. Fuel pump relay is located behind instrument panel, above parking brake lever. Turn ignition on. Measure voltage between ground and fuel pump relay harness connector terminals No. 2 and No. 5 (Black/White wires). Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, check fuse in main fuse box. Check for open or short in appropriate wire between fuse and fuel pump relay. Repair or replace as necessary.
3. Turn ignition off. Disconnect fuel pump harness connector, located along fuel tank edge. Check continuity between ground and fuel pump harness connector Black wire. Check continuity between fuel pump relay harness connector terminal No. 5 (White/Blue wire) and fuel pump harness connector White/Blue wire. Continuity should exist in both checks. If continuity exists in both circuits, go to next step. If continuity does not exist in either circuit, repair open or short in appropriate wire.
4. Ensure ignition is off. Disconnect PCM harness connector. PCM is located under center of instrument panel (connector is on driver's side). Check continuity between fuel pump relay harness connector terminal No. 1 (White/Red wire) and PCM harness connector terminal No. 11. see scheme 2 If continuity exists, go to next step. If continuity does not exist, repair open or short in White/Red wire between PCM and relay.
5. Check fuel pump relay. See «RELAYS»(ref-18079-S17347767842000122900000) under RELAYS & SOLENOIDS. Also check fuel pump. See FUEL PUMP. If fuel pump relay and fuel pump are okay, check circuit harness connectors for pushed-out, bent, damaged or corroded terminals. Repair harness or connectors as necessary.

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 under left kick panel. Turn ignition on. Measure voltage between ground and fuel pump relay harness connector terminals No. 1 (Brown 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 fuses in fuse box. See WIRING DIAGRAMS article. Check for open or short in appropriate wire between fuses 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 terminal No. 2 (Black wire). Also check continuity between fuel pump harness connector terminal No. 1 (Black/Yellow wire) and fuel pump relay harness connector terminal No. 5. Continuity should exist in both circuits. If continuity exists in both circuits, go to next step. If continuity does not exist in either circuit, repair open or short in appropriate wire.
4. Ensure ignition is off. Disconnect PCM harness connector. PCM is located under center of instrument panel (connector is on driver's side). Check continuity between fuel pump relay harness connector terminal No. 2 (Black/Pink wire) and PCM harness connector terminal No. 11. see scheme 2 If continuity exists, go to next step. If continuity does not exist, repair open or short in Black/Pink wire between PCM and relay.
5. Check fuel pump relay. See «RELAYS»(ref-18079-S17347767842000122900000) under RELAYS & SOLENOIDS. Also check fuel pump. See «FUEL PUMP»(ref-18079-S37033650412000122900000). If necessary, replace fuel pump relay or fuel pump. If fuel pump relay and fuel pump are okay, check circuit harness connectors for pushed-out, bent, damaged or corroded terminals. Repair harness or connectors as necessary.

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, on right front inner fender panel. Turn ignition on. Measure voltage between ground and fuel pump relay harness connector terminals No. 2 (Black/Yellow wire) and No. 3 (Black/Yellow wire). Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, check fuse in fuse box. Check for open or short in appropriate wire between fuse and fuel pump relay. Repair or replace as necessary.
3. Turn ignition off. Disconnect fuel pump harness connector (located under vehicle). Check continuity between ground and fuel pump harness connector terminal No. 2 (Black wire). Also check continuity between fuel pump harness connector terminal No. 1 (White/Blue wire) and fuel pump relay harness connector terminal No. 5. Continuity should exist in both circuits. If continuity exists in both circuits, go to next step. If continuity does not exist in either circuit, repair open or short in appropriate wire.
4. Ensure ignition is off. Disconnect PCM harness connector. PCM is located under center of instrument panel (connector is on driver's side). Check continuity between fuel pump relay harness connector terminal No. 1 (Red/Blue wire) and PCM harness connector terminal No. 11. see scheme 2 If continuity exists, go to next step. If continuity does not exist, repair open or short in Red/Blue wire between PCM and relay.
5. Check fuel pump relay. See «RELAYS»(ref-18079-S17347767842000122900000) under RELAYS & SOLENOIDS. Also check fuel pump. See «FUEL PUMP»(ref-18079-S37033650412000122900000). If necessary, replace fuel pump relay or fuel pump. 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.

1. If engine cranks but does not start, check inertia fuel shut-off switch. Switch is located behind driver's kick panel and is accessible through hole in kick panel. Push button down to reset switch. If gasoline fumes are present (other than during refueling), locate and repair cause of smell before resetting switch.
2. 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.
3. Turn ignition off. Disconnect fuel pump relay. Fuel pump relay is located in relay box in front of battery (second relay from left, in front row). Turn ignition on. Measure voltage between ground and fuel pump relay harness connector terminals No. 2 and No. 3 (Black/Red wires). Battery voltage should be present. If battery voltage is not present, check fuse in main fuse box. Check for open or short in appropriate wire between fuse and fuel pump relay. Repair or replace as necessary.
4. Turn ignition off. Disconnect fuel pump harness connector (located under vehicle). Check continuity between ground and fuel pump harness connector terminal No. 3 (Black/White wire). Also check continuity between fuel pump harness connector terminal No. 2 (Light Green/Red wire) and fuel pump relay harness connector terminal No. 5. Continuity should exist in both circuits. If continuity exists in both circuits, go to next step. If continuity does not exist in either circuit, repair open or short in appropriate wire. Also check inertia switch for correct operation.
5. Ensure ignition is off. Disconnect PCM harness connector. PCM is located under center of instrument panel (connector is on driver's side). Check continuity between fuel pump relay harness connector terminal No. 1 (Blue/Red wire) and PCM harness connector terminal No. 8. see scheme 1 If continuity exists, go to next step. If continuity does not exist, repair open or short in Blue/Red wire between PCM and relay.
6. Check fuel pump relay. See «RELAYS»(ref-18079-S17347767842000122900000) under RELAYS & SOLENOIDS. If relay is okay, check fuel pump. See «FUEL PUMP»(ref-18079-S37033650412000122900000). If fuel pump relay and fuel pump are okay, check circuit harness connectors for pushed-out, bent, damaged or corroded terminals. Repair harness or connectors as necessary.

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 (behind instrument panel with 2.0L engine). 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, repair or replace fuse in main fuse box and open or short in appropriate wire between fuse and fuel pump relay.
3. Turn ignition off. Disconnect fuel pump harness connector. Check continuity between ground and fuel pump harness connector terminal No. 2 (Black wire on 1.6L; Green/Red wire on 2.0L). Also check continuity between fuel pump harness connector terminal No. 1 (Black/Yellow wire) and fuel pump relay harness connector terminal No. 5. Continuity should exist. If continuity exists in both circuits, go to next step. If continuity does not exist in either circuit, repair open or short in appropriate wire.
4. Disconnect PCM harness connector. Check continuity between PCM harness connector terminal No. 8 (Black/Pink wire) and fuel pump relay harness connector terminal No. 2. see scheme 1 Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair open or short in Black/Pink wire between PCM and fuel pump relay harness connectors.
5. Check fuel pump relay. See «RELAYS»(ref-18079-S17347767842000122900000) under RELAYS & SOLENOIDS. If relay is okay, check fuel pump. See «FUEL PUMP»(ref-18079-S37033650412000122900000). If fuel pump relay and fuel pump are okay, check circuit harness connectors for pushed-out, bent, damaged or corroded terminals. Repair harness or connectors as necessary.

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 next to main fuse box panel on driver's side. Turn ignition on. Measure voltage between ground and fuel pump relay harness connector terminals No. 1 and No. 3 (Black/White wires). Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, check fuse in main fuse box. Check open or short in appropriate wire between fuse and fuel pump relay. Repair or replace as necessary.
3. Turn ignition off. Disconnect fuel pump harness connector, located in trunk. 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 circuits. If continuity exists in both circuits, go to next step. If continuity does not exist, repair open or short in appropriate wire.
4. Disconnect PCM harness connector. Check continuity between PCM harness connector terminal No. 8 (Black/Pink wire) and fuel pump relay harness connector terminal No. 2. see scheme 1 Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair open or short in Black/Pink wire between PCM and fuel pump relay harness connectors.
5. Check fuel pump relay. See «RELAYS»(ref-18079-S17347767842000122900000) under RELAYS & SOLENOIDS. If relay is okay, check fuel pump. See «FUEL PUMP»(ref-18079-S37033650412000122900000). If fuel pump relay and fuel pump are okay, check circuit harness connectors for pushed-out, bent, damaged or corroded terminals. Repair harness or connectors as necessary.

FUEL PUMP CONTROL MODULE (FPCM)

Faults in fuel pump control module & dropping resistor circuit should set Diagnostic Trouble Code (DTC) P1220. To test system, see DTC P1220: FUEL PUMP CONTROL MODULE (FPCM) procedures in TESTS W/CODES article.

FUEL INJECTOR

Disconnect fuel injector harness connector. Check resistance across injector connector terminals. Resistance should be 10-14 ohms. If resistance is not as specified, replace injector. If resistance is okay, remove injector. If nozzle is clogged, replace injector.

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 wire(s). Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, check fusible link, ignition switch, and open or short in Black/Red wire between ignition switch and injector(s). Repair or replace as necessary. See WIRING DIAGRAMS article.
3. Turn ignition off. Disconnect PCM harness connector. Check continuity between specified PCM harness connector terminal and appropriate injector harness connector terminal. See «INJECTOR CIRCUIT IDENTIFICATION (ALTIMA)»(ref-18079-S32479617962000122900000) table. If continuity exists in each circuit, go to next step. If continuity does not exist in any circuit, repair open or short in appropriate wire between PCM and injector harness connectors.
4. Check fuel injector(s). See «FUEL INJECTOR»(ref-18079-S14156131912000122900000) . If fuel injectors are okay, check PCM harness connector terminals for damage or corrosion. Repair or replace as necessary.

INJECTOR CIRCUIT IDENTIFICATION (ALTIMA)

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 wire(s). Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, check fuse and open or short in Black/Red wire between fuse box and injector harness connector. Repair or replace as necessary. See WIRING DIAGRAMS article.
3. Turn ignition off. Disconnect PCM harness connector. Check continuity between specified PCM harness connector terminal and appropriate injector harness connector terminal. See «INJECTOR CIRCUIT IDENTIFICATION (FRONTIER)»(ref-18079-S23431407512000122900000) table. If continuity exists in each circuit, go to next step. If continuity does not exist in any circuit, repair open or short in appropriate wire between PCM and injector harness connectors.
4. Check fuel injector(s). See «FUEL INJECTOR»(ref-18079-S14156131912000122900000) . If fuel injectors are okay, check PCM harness connector terminals for damage or corrosion. Repair or replace as necessary.

INJECTOR CIRCUIT IDENTIFICATION (FRONTIER)

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. To test left bank injectors, disconnect injector harness connector(s). To test right bank injectors, disconnect injector sub-harness connector. (Scheme 49) Turn ignition on. On left bank injectors, measure voltage between ground and injector harness connector Red wire(s). On right bank injectors, measure voltage between injector sub-harness connector terminal No. 5. (Scheme 50) Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, check fusible link, ignition switch, and open or short in Red wire between ignition switch and injector(s) harness connector or sub-harness connector. Repair or replace as necessary. See WIRING DIAGRAMS article.
3. Turn ignition off. Disconnect PCM harness connector. Check continuity between specified PCM harness connector terminal and appropriate injector harness or sub-harness connector terminal. See «INJECTOR CIRCUIT IDENTIFICATION (MAXIMA)»(ref-18079-S09592357292000122900000) table. If continuity exists in each circuit, go to next step. If continuity does not exist in any circuit, repair open or short in appropriate wire between PCM and injector harness or sub-harness connectors.
4. Remove intake manifold collector from intake manifold. On right bank injectors, check continuity between injector sub-harness connector terminal No. 5 and each injector harness connector terminal No. 2 (Red wire). Also check continuity between injector harness connector terminal No. 1 and appropriate injector sub-harness connector terminal. See «INJECTOR CIRCUIT IDENTIFICATION (MAXIMA)»(ref-18079-S09592357292000122900000) table. If continuity exists on each circuit, go to next step. If continuity does not exist on any circuit, repair open or short in appropriate wire.
5. Check fuel injector(s). See «FUEL INJECTOR»(ref-18079-S14156131912000122900000). If fuel injectors are okay, check PCM harness connector terminals for damage or corrosion. Repair or replace as necessary.

INJECTOR CIRCUIT IDENTIFICATION (MAXIMA)

Scheme 49

Scheme 50

1. If engine does not start, go to step 5). 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 White/Red wire(s). Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, check for open or short in White/Red wire between ECCS relay and injector(s) harness connector. Repair or replace as necessary. See WIRING DIAGRAMS article.
3. Turn ignition off. Disconnect PCM harness connector. Check continuity between specified PCM harness connector terminal and appropriate injector harness connector terminal. See «INJECTOR CIRCUIT IDENTIFICATION (PATHFINDER & QX4)»(ref-18079-S23094990432000122900000). If continuity exists in each circuit, go to next step. If continuity does not exist in any circuit, repair open or short in appropriate wire between PCM and injector harness connectors.
4. Check fuel injector(s). See «FUEL INJECTOR»(ref-18079-S14156131912000122900000). If fuel injectors are okay, check PCM harness connector terminals for damage or corrosion. Repair or replace as necessary.
5. Turn ignition off. Disconnect 8-pin injector sub-harness connector, located on driver's side of oil filler cap. Turn ignition on. Measure voltage between ground and injector sub-harness connector terminal No. 1 (White/Red wire). (Scheme 50) Battery voltage should be present. If battery voltage is not present, go to next step. If battery voltage is present, turn ignition off, reconnect injector sub-harness connector and go to step 2).
6. Turn ignition off. Disconnect ECCS relay (located in relay/fuse box next to battery; relay closest to fender). Measure voltage between ground and ECCS relay harness connector terminals No. 1 and No. 5. (Scheme 46) Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, check fuses and open or short in appropriate wire between ECCS relay harness connector and battery. Repair or replace as necessary. See WIRING DIAGRAMS article.
7. Check continuity between ECCS relay harness connector terminal No. 3 and injector sub-harness connector terminal No. 1 (White/Red wire). Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair open or short in White/Red wire between ECCS relay and injector sub-harness connectors.
8. Ensure ignition is turned off. Disconnect PCM connector. Check continuity between PCM harness connector terminal No. 4 and ECCS relay harness connector terminal No. 2 (Blue/Black wire). see scheme 2& (Scheme 46). Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair open or short in Blue/Black wire between PCM and ECCS relay harness connectors.
9. Check ECCS relay. See «RELAYS»(ref-18079-S17347767842000122900000) under RELAYS & SOLENOIDS. If relay is not okay, replace ECCS relay. If relay is okay, intermittent or PCM fault exists. Check PCM power and ground circuits. See «POWERTRAIN CONTROL MODULE (PCM)»(ref-18079-S36953255152000122900000) under COMPUTERIZED ENGINE CONTROLS.

INJECTOR CIRCUIT IDENTIFICATION (PATHFINDER & QX4)

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 Yellow wire(s). Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, check fusible link, ignition switch, and open or short in Yellow wire between ignition switch and injector(s). Repair or replace as necessary. See WIRING DIAGRAMS article.
3. Turn ignition off. Disconnect PCM harness connector. Check continuity between specified PCM harness connector terminal and appropriate injector harness connector terminal. See «INJECTOR CIRCUIT IDENTIFICATION (QUEST)»(ref-18079-S20249327232000122900000) table. If continuity exists in each circuit, go to next step. If continuity does not exist in any circuit, repair open or short in appropriate wire between PCM and injector harness connectors.
4. Check fuel injector(s). See «FUEL INJECTOR»(ref-18079-S14156131912000122900000) . If fuel injectors are okay, check PCM harness connector terminals for damage or corrosion. Repair or replace as necessary.

INJECTOR CIRCUIT IDENTIFICATION (QUEST)

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 wire(s) on 1.6L models and White wire(s) on 2.0L models. Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, check fuse and open or short in Black/Red or White wire between fuse box and injector harness connector. Repair or replace as necessary. See WIRING DIAGRAMS article.
3. Turn ignition off. Disconnect PCM harness connector. Check continuity between specified PCM harness connector terminal and appropriate injector harness connector terminal. See «INJECTOR CIRCUIT IDENTIFICATION (SENTRA & 200SX)»(ref-18079-S24917356712000122900000) table. If continuity exists in each circuit, go to next step. If continuity does not exist in any circuit, repair open or short in appropriate wire between PCM and injector harness connectors.
4. Check fuel injector(s). See «FUEL INJECTOR»(ref-18079-S14156131912000122900000) . If fuel injectors are okay, check PCM harness connector terminals for damage or corrosion. Repair or replace as necessary.

INJECTOR CIRCUIT IDENTIFICATION (SENTRA & 200SX)

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 wire(s). Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, check fusible link, ignition switch, and open or short in Black/Red wire between ignition switch and injector(s). Repair or replace as necessary. See WIRING DIAGRAMS article.
3. Turn ignition off. Disconnect PCM harness connector. Check continuity between specified PCM harness connector terminal and appropriate injector harness connector terminal. See «INJECTOR CIRCUIT IDENTIFICATION (240SX)»(ref-18079-S34797917552000122900000) table. If continuity exists in each circuit, go to next step. If continuity does not exist in any circuit, repair open or short in appropriate wire between PCM and injector harness connectors.
4. Check fuel injector(s). See «FUEL INJECTOR»(ref-18079-S14156131912000122900000) . If fuel injectors are okay, check PCM harness connector terminals for damage or corrosion. Repair or replace as necessary.

INJECTOR CIRCUIT IDENTIFICATION (240SX)

IDLE AIR CONTROL (IAC) VALVE

Faults in IAC valve or circuit should set Diagnostic Trouble Code (DTC) P0505. To test system, see procedures in DTC P0505: IDLE AIR CONTROL (IAC) VALVE in TESTS W/CODES article.

IDLE AIR CONTROL (IAC) VALVE AIR REGULATOR

Disconnect IAC valve air regulator harness connector. Measure resistance between air regulator terminals. Resistance should be 70-80 ohms at 77°F (25°C). If resistance is not as specified, replace IAC valve air regulator.

Sentra (2.0L Models), 200SX (2.0L Models) & 240SX

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 IAC valve air regulator harness connector. Turn ignition on. Measure voltage between ground and IAC valve air regulator harness connector terminal No. 1 (Black/Yellow wire). Battery voltage should be present for 5 seconds after ignition is turned on. If battery voltage is as specified, go to next step. If battery voltage is not as specified, check fuse and open or short in Black/Yellow wire between fuel pump relay and IAC valve air regulator harness connector. Repair or replace as necessary.
3. Turn ignition off. Check continuity between ground and IAC valve air regulator harness connector terminal No. 2 (Black wire on Sentra and 200SX; Blue/White wire on 240SX). Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair open or short in Black or Blue/White wire.
4. Check IAC valve air regulator. See «IDLE AIR CONTROL (IAC) VALVE AIR REGULATOR»(ref-18079-S17049158792000122900000) . Replace as necessary. If IAC valve air regulator is okay, check circuit harness connector terminals for pushed-out, bent, damaged or corroded terminals. Repair harness or connectors as necessary.

Disconnect FICD solenoid harness connector. Apply battery voltage across solenoid terminals. If solenoid does not operate, check for sticking plunger or broken spring. If plunger and spring are okay, replace solenoid.

1. Start engine and warm to operating temperature. Check idle speed. See SPECIFICATIONS article. Adjust idle speed if necessary. See ADJUSTMENTS article. Turn A/C switch and blower fan switch on. Idle speed should increase. If idle speed does not increase, go to next step. If idle speed increases, system is functioning properly.
2. Ensure A/C compressor functions normally. If compressor is not functioning, repair A/C system as necessary. If compressor is functioning, go to next step.
3. Turn ignition off. Disconnect FICD solenoid harness connector. Start engine. Using DVOM, measure voltage between ground and FICD harness connector terminal No. 1 (Yellow/Black wire). Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, check and repair open or short in Yellow/Black wire. If wire is okay, check fuse, A/C relay, and FICD solenoid. Repair or replace as necessary.
4. Check ambient air temperature switch. See A/C-HEATER SYSTEMS article in the AIR CONDITIONING & HEAT section. If ambient air temperature switch is okay, go to next step. If ambient air temperature switch is not okay, replace as necessary. Retest system.
5. Ensure engine is still at operating temperature. Turn ignition off. Check continuity between ground and FICD solenoid harness connector terminal No. 2 (Black wire). Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair open in Black wire.
6. Check FICD solenoid. See «FAST IDLE CONTROL DEVICE (FICD) SOLENOID»(ref-18079-S34940576822000122900000) . If FICD solenoid is okay, check PCM terminals and harness connector terminals for pushed-out, damaged, or corroded terminals. Repair or replace as necessary.

1. Start engine and warm to operating temperature. Check idle speed. See SPECIFICATIONS article. Adjust idle speed if necessary. See ADJUSTMENTS article. Turn A/C switch and blower fan switch on. Idle speed should increase. If idle speed does not increase, go to next step. If idle speed increases, system is functioning properly.
2. Ensure A/C compressor functions normally. If compressor is not functioning, repair A/C system as necessary. If compressor is functioning, go to next step.
3. Turn ignition off. Disconnect FICD solenoid harness connector. Start engine and let it idle. Measure voltage between ground and FICD harness connector terminal No. 2 (Green/Black wire). Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, check and repair open or short in Green/Black wire. If wire is okay, check fuse, A/C relay, and FICD solenoid. Repair or replace as necessary.
4. Turn ignition off. Check continuity between ground and FICD solenoid harness connector terminal No. 1 (Black/Red wire). Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair open in Black/Red wire.
5. Check FICD solenoid. See «FAST IDLE CONTROL DEVICE (FICD) SOLENOID»(ref-18079-S34940576822000122900000) . If FICD solenoid is okay, check PCM terminals and harness connector terminals for pushed-out, damaged, or corroded terminals. Repair or replace as necessary.

1. Start engine and warm to operating temperature. Check idle speed. See SPECIFICATIONS article. Adjust idle speed if necessary. See ADJUSTMENTS article. Turn A/C switch and blower fan switch on. Idle speed should increase. If idle speed does not increase, go to next step. If idle speed increases, system is functioning properly.
2. Ensure A/C compressor functions normally. If compressor is not functioning, repair A/C system as necessary. If compressor is functioning, go to next step.
3. Turn ignition off. Disconnect FICD solenoid harness connector. Start engine and let it idle. Measure voltage between ground and FICD harness connector terminal No. 1 (Yellow/Black wire). Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, check and repair open or short in Yellow/Black wire. If wire is okay, check fuse, A/C relay, and FICD solenoid. Repair or replace as necessary.
4. Turn ignition off. Check continuity between ground and FICD solenoid harness connector terminal No. 2 (Black wire). Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair open in Black wire or connectors. On automatic A/C equipped models, ensure automatic A/C control unit is functioning normally. See A/C-HEATER SYSTEMS article in the AIR CONDITONING & HEAT section.
5. Check FICD solenoid. See «FAST IDLE CONTROL DEVICE (FICD) SOLENOID»(ref-18079-S34940576822000122900000) . If FICD solenoid is okay, check PCM terminals, harness, and connector terminals for pushed-out, damaged, or corroded terminals. Repair or replace as necessary.

1. Start engine and warm to operating temperature. Check idle speed. See SPECIFICATIONS article. Adjust idle speed if necessary. See ADJUSTMENTS article. Turn A/C switch and blower fan switch on. Idle speed should increase. If idle speed does not increase, go to next step. If idle speed increases, system is functioning properly.
2. Ensure A/C compressor functions normally. If compressor is not functioning, repair A/C system as necessary. If compressor is functioning, go to next step.
3. Turn ignition off. Disconnect FICD solenoid harness connector. Start engine and let it idle. Measure voltage between ground and FICD harness connector terminal No. 1 (Black/White wire). Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, check and repair open or short in Black/White wire. If wire is okay, check fuse, A/C relay, and FICD solenoid. Repair or replace as necessary.
4. Turn ignition off. Disconnect ambient air temperature switch harness connector. Check continuity between FICD solenoid harness connector terminal No. 2 (Green/Orange wire) and ambient air temperature switch harness connector terminal No. 1. Also check continuity between ambient air temperature switch connector terminal No. 2 (Black wire) and ground. Continuity should exist between both measurements. If continuity exists as specified, go to next step. If continuity does not exist as specified, repair open or short in appropriate wire. Also check diode and harness connectors. See WIRING DIAGRAMS article. On automatic A/C equipped models, ensure automatic A/C control unit is functioning normally. See A/C-HEATER SYSTEMS article in the AIR CONDITIONING & HEAT section.
5. Check ambient air temperature switch. See A/C-HEATER SYSTEMS article in the AIR CONDITIONING & HEAT section. Replace as necessary. If ambient air temperature switch is okay, check FICD solenoid. See «FAST IDLE CONTROL DEVICE (FICD) SOLENOID»(ref-18079-S34940576822000122900000) . If FICD solenoid is okay, check PCM terminals and harness connector terminals for pushed-out, damaged, or corroded terminals. Repair or replace as necessary.

1. Start engine and warm to operating temperature. Check idle speed. See SPECIFICATIONS article. Adjust idle speed if necessary. See ADJUSTMENTS article. Turn A/C and blower fan switches on. Idle speed should increase. If idle speed does not increase, go to next step. If idle speed increases, system is functioning properly.
2. Ensure A/C compressor functions normally. If compressor is not functioning, repair A/C system as necessary. If compressor is functioning, go to next step.
3. Turn ignition off. Disconnect FICD solenoid harness connector. Using DVOM, measure voltage between ground and FICD solenoid harness connector terminal No. 1 (Blue/Yellow 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. See WIRING DIAGRAMS article. If fuse is okay, repair open or short in Blue/Yellow wire. Also check Blue wire between fuse and FICD relay, harness connectors and FICD relay. See «RELAYS»(ref-18079-S17347767842000122900000) under RELAYS & SOLENOIDS.
4. Turn ignition off. Check continuity between ground and FICD solenoid harness connector terminal No. 2 (Black wire). Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair open Black wire.
5. Check FICD solenoid. See «FAST IDLE CONTROL DEVICE (FICD) SOLENOID»(ref-18079-S34940576822000122900000) . If FICD solenoid is okay, check PCM and harness connector terminals for damage or corrosion. Repair or replace as necessary and go to next step.
6. Start engine. Using DVOM, measure voltage between PCM harness connector terminal No. 21 (White/Red wire) and ground by backprobing connector. Voltage should be 2.3 volts with A/C and blower fan switch on and ambient air temperature more than 50°F (10°C). Voltage should be approximately battery voltage with A/C off. If voltage is as specified, system is functioning properly. If voltage is not as specified, diagnose fault in A/C system. See A/C-HEATER SYSTEMS article in the AIR CONDITIONING & HEAT section.

1. Start engine and warm to operating temperature. Check idle speed. See SPECIFICATIONS article. Adjust idle speed if necessary. See ADJUSTMENTS article. Turn A/C switch and blower fan switch on. Idle speed should increase. If idle speed does not increase, go to next step. If idle speed increases, system is functioning properly.
2. Ensure A/C compressor functions normally. If compressor is not functioning, repair A/C system as necessary. If compressor is functioning, go to next step.
3. Turn ignition off. Disconnect FICD solenoid harness connector. Start engine and let it idle. Using DVOM, measure voltage between ground and FICD harness connector terminal No. 1 (Blue/Red wire). Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, check 7.5-amp fuse. If fuse is okay, repair open in Blue/Red wire. Also check A/C relay and Light Green wire between A/C relay and fuse block. Repair or replace as necessary.
4. Turn ignition off. Check continuity between ground and FICD solenoid harness connector terminal No. 2 (Black wire). Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair open in Black wire.
5. Check FICD solenoid. See «FAST IDLE CONTROL DEVICE (FICD) SOLENOID»(ref-18079-S34940576822000122900000) . If FICD solenoid is okay, check PCM and harness connector terminals for pushed-out, damaged, or corroded terminals. Repair or replace as necessary.

1. Start engine and warm to operating temperature. Check idle speed. See SPECIFICATIONS article. Adjust idle speed if necessary. See ADJUSTMENTS article. Turn A/C switch and blower fan switch on. Idle speed should increase. If idle speed does not increase, go to next step. If idle speed increases, system is functioning properly.
2. Ensure A/C compressor functions normally. If compressor is not functioning, repair A/C system as necessary. If compressor is functioning, go to next step.
3. Turn ignition off. Disconnect FICD solenoid sub-harness connector located above upper radiator hose engine inlet tube. Start engine and let it idle. Using DVOM, measure voltage between ground and FICD sub-harness connector terminal No. 3 (Blue/Red wire). Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, repair open in Blue/Red wire between A/C relay and FICD solenoid sub-harness connector. See WIRING DIAGRAMS article. Also check A/C relay and Green/Black wire between A/C relay and fuse block.
4. Turn ignition off. Disconnect FICD solenoid sub-harness connector. Check continuity between FICD solenoid sub-harness connector terminal No. 4 (Green wire) and ambient air temperature switch harness connector terminal No. 1 (Blue/White wire). Also check continuity between ground and ambient air temperature switch harness connector terminal No. 2 (Black wire). Continuity should exist. If continuity exists, go to next step. If continuity does not exist, check and repair or replace appropriate wire. See WIRING DIAGRAMS article. Also check diode and ambient air temperature switch.
5. Check FICD solenoid. See «FAST IDLE CONTROL DEVICE (FICD) SOLENOID»(ref-18079-S34940576822000122900000) . If FICD solenoid is okay, check PCM and harness connector terminals for pushed-out, damaged, or corroded terminals. Repair or replace as necessary.

IGNITION SYSTEMS

Faults in ignition signal should set DTC P1320. For testing procedure, refer to DTC P1320: IGNITION SIGNAL in TESTS W/CODES article.

POWER TRANSISTOR

Faults in power transistor should set DTC P1320. For testing procedure, refer to DTC P1320: IGNITION SIGNAL in TESTS W/CODES article.

Timing Advance

Ignition timing advance is controlled by the PCM based upon sensor input signals. If timing problems are experienced, inspect input signals for proper operation. See PIN VOLTAGE CHART S article. Inputs that affect timing include the following

1. Camshaft or crankshaft position sensor.
2. Airflow meter.
3. Engine (coolant) temperature sensor.
4. Idle switch.
5. Start (cranking) signal.
6. Battery voltage.

Detonation (Knock) Retard

Check knock sensor wire for open or short to ground. Check knock sensor shield ground wire for continuity to ground. Check routing of knock sensor wire. Wire should not be routed close to spark plug wires or high output accessories.

Faults in knock sensor circuit may set or DTC P0325. To test system, refer to DTC P0325: KNOCK SENSOR (KS) in TESTS W/CODES article.

Scheme 51

Carbon Canister (Altima & Quest)

Remove hoses from carbon canister. Blow air into canister ports as shown. (Scheme 52) Air should pass through vent and purge lines, but should not pass through vacuum lines.

Carbon Canister (Except Altima & Quest)

Remove hoses from carbon canister. Blow air into canister ports as shown. (Scheme 53) Air should pass through vent and purge lines, but should not pass through vacuum lines.

Fuel Tank Vacuum Relief Valve

Valve is located in fuel tank filler cap. Wipe cap clean to prevent inhaling fuel vapors. Find a way to safely apply light vacuum to cap on side of cap that faces fuel tank. A slight resistance accompanied by clicks indicates the valve is okay. By applying more vacuum, resistance should no longer be felt and clicks should no longer be heard. If valve does not operate as specified, replace fuel tank filler cap.

Scheme 52

Scheme 53

EGR Backpressure Transducer (EGR-BPT)

Plug one port on top of EGR-BPT valve and apply vacuum to other port. Vacuum should NOT hold. Apply light pressure to bottom port (DO NOT apply more pressure than is necessary to cause vacuum to hold). If vacuum does not hold with pressure applied, replace EGR-BPT.

EGR Control Solenoid

Faults in EGR control solenoid circuit should set DTC P1400. To test circuit, see DTC P1400 diagnostic procedures in appropriate TESTS W/CODES article.

EGR Function

Faults in EGR function circuit should set DTC P0400. To test function, see DTC P0400 diagnostic procedures in TESTS W/CODES article.

EGR Valve

1. With engine idling, disconnect EGR vacuum line. Using a vacuum pump, apply vacuum to EGR valve. Engine speed should decrease or engine should stall. If engine does not respond in this manner, go to next step. Vacuum should hold on gauge. If vacuum does not hold, replace EGR valve.
2. Manually compress EGR valve diaphragm from underside. If engine speed does not decrease or engine does not stall, remove EGR valve and inspect EGR passages for plugging. If engine speed decreases or engine stalls, replace EGR valve.

POSITIVE CRANKCASE VENTILATION (PCV)

With engine idling, remove PCV valve with hose connected. If a hissing noise and strong vacuum are not present at valve end, check hose and hose connections for leaks or obstructions. If hose is okay, replace PCV valve.

Drain and remove fuel tank. See REMOVE/INSTALL/OVERHAUL article. Apply air pressure to EVAP vapor cut valve hose and ensure air flows into fuel tank. Remove fuel gauge assembly from fuel tank. Attach vacuum pump to EVAP vapor cut valve port. Turn fuel tank over. Apply 3.94 in. Hg of vacuum to EVAP vapor cut valve. Ensure a vacuum exists at fuel gauge opening. If vacuum does not exist, replace EVAP vapor cut valve with fuel tank.

Sentra 2.0L & 200SX 2.0L

Drain and remove fuel tank. See REMOVE/INSTALL/OVERHAUL article. Apply air pressure to EVAP vapor cut valve hose and ensure air flows into fuel tank. Remove fuel gauge assembly from fuel tank. Using vacuum pump, apply 3.94 in. Hg of vacuum to EVAP vapor cut valve port and signal line. (Scheme 54) Ensure a vacuum exists at fuel gauge opening. If vacuum does not exist, replace EVAP vapor cut valve with fuel tank.

Scheme 54

Drain and remove fuel tank. See REMOVE/INSTALL/OVERHAUL article. Blow air through refueling control valve port "A" and ensure air flows out of port "B". (Scheme 55) Using vacuum pump, apply 5.91 in. Hg of vacuum to refueling control valve ports "A" and "C" and ensure vacuum does not exist at port "B". If operation is not as specified, replace refueling control valve and retest system.

Blow air through EVAP vapor cut valve port and ensure air flows into fuel tank. (Scheme 54) Blow air through signal line and ensure air does not flow into fuel tank. Using vacuum pump, apply 5.91 in. Hg to EVAP vapor cut valve port and signal line. If operation is not as specified, replace refueling control valve with fuel tank and retest system.

Scheme 55

Strong Fuel Odor From Evap Canister (Altima)

1. Check EVAP purge line for cracks. Remove EVAP canister with EVAP canister vent control valve attached. Turn EVAP canister over and check for water leaking from EVAP canister vent control valve. If water is not leaking from valve, go to next step. If water is leaking from valve, weigh EVAP canister with valve attached. If canister is less than 4.0 lbs. (1.8 kg), go to next step. If canister is equal to or more than 4.0 lbs. (1.8 kg), replace EVAP canister and retest system.
2. Check EVAP vapor cut valve. See «EVAP VAPOR CUT VALVE»(ref-18079-S08973176922000122900000) . Repair or replace as necessary. If operation is as specified, go to next step.
3. Check vacuum lines to refueling control valve. See VACUUM DIAGRAMS article. Check refueling control valve. See «REFUELING CONTROL VALVE»(ref-18079-S35852726672000122900000) . If operation is not as specified, replace refueling control valve and retest system. If operation is as specified, check vacuum lines and connections for cracks or clogging and repair as necessary.

Strong Fuel Odor From Evap Canister (Sentra 2.0L & 200SX 2.0L)

1. Check EVAP purge line for cracks. Remove EVAP canister with EVAP canister vent control valve attached. Turn EVAP canister over and check for water leaking from EVAP canister vent control valve. If water is not leaking from valve, go to next step. If water is leaking from valve, weigh EVAP canister with valve attached. If canister is less than 4.0 lbs. (1.8 kg), go to next step. If canister is equal to or more than 4.0 lbs. (1.8 kg), replace EVAP canister and retest system.
2. Drain and remove fuel tank. See procedures in REMOVE/INSTALL/OVERHAUL article. Check EVAP vapor cut valve. See «EVAP VAPOR CUT VALVE»(ref-18079-S08973176922000122900000) . If operation is as specified, go to next step. If operation is not as specified, replace EVAP vapor cut valve with fuel tank.
3. Check vacuum lines to refueling control valve. See VACUUM DIAGRAMS article. Check refueling control valve. See «REFUELING CONTROL VALVE»(ref-18079-S35852726672000122900000) . If operation is not as specified, replace refueling control valve with fuel tank and retest system. If operation is as specified, check vacuum lines and connections for cracks or clogging and repair as necessary.

Cannot Refuel Or Fuel Odor From Fuel Filler Opening While Refueling

1. Check EVAP purge line for cracks. Remove EVAP canister with EVAP canister vent control valve attached. Turn EVAP canister over and check for water leaking from EVAP canister vent control valve. If water is not leaking from valve, go to next step. If water is leaking from valve, weigh EVAP canister with valve attached. If canister is less than 4.0 lbs. (1.8 kg), go to next step. If canister is equal to or more than 4.0 lbs. (1.8 kg), replace EVAP canister and retest system.
2. Check vapor lines between EVAP canister and refueling control valve for clogging, cracks or loose/improper connections. Also check fuel filler neck and tube for clogging, kinking or loose/improper connection. Repair or replace as necessary. If vapor lines are okay, go to next step.
3. Drain and remove fuel tank. See procedures in REMOVE/INSTALL/OVERHAUL article. Check EVAP vapor cut valve. See «EVAP VAPOR CUT VALVE»(ref-18079-S08973176922000122900000) . If operation is as specified, go to next step. If operation is not as specified, replace EVAP vapor cut valve with fuel tank.
4. Check vacuum lines to refueling control valve. See VACUUM DIAGRAMS article. Check refueling control valve. See «REFUELING CONTROL VALVE»(ref-18079-S35852726672000122900000) . If operation is as specified, go to next step. If operation is not as specified, replace refueling control valve with fuel tank and retest system.
5. Disconnect fuel filler tube from fuel tank. Insert suitable rod to check one-way fuel valve. One-way fuel valve should move in with rod inserted and move out with rod removed. If operation is not as specified, replace one-way fuel valve with fuel tank. If operation is as specified, check vacuum lines and connections for cracks or clogging and repair as necessary.

MISCELLANEOUS CONTROLS

Note. Although some of the controlled devices listed here are not engine performance components, they can affect driveability if they malfunction.

1. Turn ignition off. Disconnect PCM harness connector. Turn ignition on. Measure voltage between ground and PCM harness connector terminal No. 55 (Blue/Red wire). see scheme 1 With rear window defogger on, battery voltage should exist. With rear window defogger off, zero volts should exist. If voltage is not as specified, go to step 3). If voltage is as specified, go to next step.
2. Measure voltage between ground and PCM harness connector terminal No. 60 (Brown wire). With headlight switch on, battery voltage should exist. With headlight switch off, zero volts should exist. If voltage is not as specified, go to next step. If voltage is as specified, system is functioning normally.
3. Turn ignition off. Check rear window defogger or headlight switch for correct operation. See REAR WINDOW DEFOGGERS article or HEADLIGHT SYSTEMS article in the ACCESSORIES/SAFETY EQUIP section. If rear window defogger or headlight switch operates normally, go to next step. If rear window defogger or headlight switch does not operate normally, repair as necessary.
4. Check continuity between ground and PCM harness connector terminal No. 59 (Light Green/Red wire). see scheme 1 Turn A/C blower fan switch on. Continuity should exist with blower fan on and no continuity should exist with blower fan switch off. If continuity is as specified, go to next step. If continuity is not as specified, check and repair open or short in appropriate wire between PCM and A/C blower fan switch. Also check blower fan switch and harness connector terminals for pushed-out, bent, damaged or corroded terminals. See WIRING DIAGRAMS article.

1. Turn ignition off. Disconnect PCM harness connector. Turn ignition on. Measure voltage between ground and PCM harness connector terminal No. 79 (Red/White wire). see scheme 2 With rear window defogger on, battery voltage should exist. With rear window defogger off, zero volts should exist. If voltage is not as specified, go to next step. If voltage is as specified, system is functioning properly.
2. Turn ignition off. Check rear window defogger for correct operation. See appropriate REAR WINDOW DEFOGGERS article in the ACCESSORIES/SAFETY EQUIP section. If rear window defogger operates normally, go to next step. If rear window defogger does not operate normally, repair as necessary.
3. Disconnect rear window defogger relay. Check continuity between PCM terminal No. 79 (Red/White wire) and rear window defogger relay harness connector terminal No. 5 (Blue/Red wire) and terminal No. 7 (Blue/Yellow wire). see scheme 2 Continuity should exist. If continuity exists, go to next step. If continuity does not exist, check and repair appropriate wire between PCM and relay. Also check for blown fuses and/or circuit harness connector terminals for pushed-out, bent, damaged or corroded terminals. Repair harness or connectors as necessary. See WIRING DIAGRAMS article.

Sentra & 200SX (1.6L Only)

1. Turn ignition off. Disconnect PCM harness connector. Turn ignition on. Measure voltage between ground and PCM harness connector terminal No. 55 (Blue/Red wire). see scheme 1 With rear window defogger on, battery voltage should exist. With rear window defogger off, zero volts should exist. If voltage is not as specified, go to step 3). If voltage is as specified, go to next step.
2. Measure voltage between ground and PCM harness connector terminal No. 60 (Red/Blue wire). With headlight switch on, battery voltage should exist. With headlight switch off, zero volts should exist. If voltage is not as specified, go to next step. If voltage is as specified, system is functioning normally.
3. Turn ignition off. Check rear window defogger or headlight switch for correct operation. See REAR WINDOW DEFOGGERS article or HEADLIGHT SYSTEMS article in the ACCESSORIES/SAFETY EQUIP section. If rear window defogger and headlight switch operates normally, go to next step. If rear window defogger or headlight switch does not operate normally, repair as necessary.
4. Check continuity between ground and PCM harness connector terminal No. 24 (Light Green/Blue wire). see scheme 1 Turn A/C blower fan switch on. Continuity should exist with blower fan on and no continuity should exist with blower fan switch off. If continuity is as specified, go to next step. If continuity is not as specified, check and repair open or short in Light Green/Blue wire between PCM and A/C blower fan switch. Also check blower fan switch, PCM and harness connector terminals for pushed-out, bent, damaged or corroded terminals. See WIRING DIAGRAMS article.

1. Turn ignition off. Disconnect PCM harness connector. Turn ignition on. Measure voltage between ground and PCM harness connector terminal No. 55 (Blue/Red wire). see scheme 1 With rear window defogger on, battery voltage should exist. With rear window defogger off, zero volts should exist. If voltage is not as specified, go to step 3). If voltage is as specified, go to next step.
2. Measure voltage between ground and PCM harness connector terminal No. 60 (Red/Yellow wire). With headlight switch on, battery voltage should exist. With headlight switch off, zero volts should exist. If voltage is not as specified, go to next step. If voltage is as specified, system is functioning normally.
3. Turn ignition off. Check rear window defogger for correct operation. See REAR WINDOW DEFOGGERS article in the ACCESSORIES/SAFETY EQUIP section. If rear window defogger operates normally, go to next step. If rear window defogger does not operate normally, repair as necessary.
4. Disconnect rear window defogger and headlight switch harness connectors. Check continuity between PCM harness connector terminal No. 55 (Blue/Red wire) and rear window defogger relay terminal No. 5. see scheme 1 Also check continuity between PCM harness connector terminal No. 60 (Red/Yellow wire) and headlight switch harness connector terminal No. 10. Continuity should exist. If continuity exists, go to next step. If continuity does not exist, check and repair appropriate wire between PCM and relay. Also check fuses and harness connector terminals for pushed-out, bent, damaged or corroded terminals. See WIRING DIAGRAMS article.

FRONT ENGINE MOUNTING CONTROL (MAXIMA ONLY)

1. Warm engine to operating temperature and allow it to idle. Apply parking brake. Apply brake pedal and move shift selector lever to "D" position and note engine vibration. With engine speed more than 1000 RPM, disconnect front engine mounting control harness connector. (Scheme 56) Reduce engine speed to idle and note engine vibration again. If vibration did not increase with front engine mounting control harness connector disconnected, go to next step. If vibration increased with front engine mounting control harness connector disconnected, system is working properly.
2. Turn ignition off. Measure voltage between ground and front engine mounting control harness connector White wire. Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, check fuse and open or short in White wire. Repair or replace as necessary. See WIRING DIAGRAMS article.
3. Disconnect PCM connector. Check continuity between PCM harness connector terminal No. 33 and front engine mounting control harness connector White/Blue wire. Also check continuity between PCM harness connector terminal No. 34 and front engine mounting control harness connector White/Red wire. Continuity should exist. If continuity exists in each circuit, go to next step. If continuity does not exist in either circuit, repair open or short in appropriate wire.
4. Check PCM and harness connector terminals for pushed-out, bent, damaged or corroded terminals. Repair harness or connectors as necessary. If circuit is okay, replace front engine mounting control assembly and retest system.

Scheme 56

Except Frontier, Pathfinder, QX4 & 240SX

The PCM controls electric radiator cooling fan(s) based on vehicle speed, engine coolant temperature and A/C switch position. A fault in radiator fan control circuit should set MIL 0208. To test system, see diagnostic procedures in MIL 0208: RADIATOR COOLING FAN CONTROL in TESTS W/CODES article.

1. Turn ignition off. Disconnect 5th position switch 2-pin harness connector located on side of passengers side transmission housing. Check continuity between ground and 5th position switch 2-pin harness connector Black wire. Continuity should exist. If continuity exists, go to next step. If continuity does not exist, check harness and connectors between switch and ground.
2. Disconnect PCM harness connector. Check continuity between PCM terminal No. 7 (Yellow/Blue wire) and 5th position switch 2-pin harness connector Yellow/Blue wire. Continuity should exist. If continuity exists, go to next step. If continuity does not exist, check and repair open in Yellow/Blue wire between PCM and switch.
3. With transmission in 5th gear, ensure continuity exists at 5th position switch connector. Replace switch if necessary. If switch is okay, check and repair PCM and harness connector terminals for pushed-out, bent, damaged or corroded terminals. Repair harness or connectors as necessary.