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Engine Controls - System/component Tests 2.4L: Diagnosis Nissan 240SX S14

Testing & Diagnostics 1 illustration ~2640 words

INHIBITOR SWITCH SYSTEM TEST

  1. Ensure inhibitor switch functions properly. See INHIBITOR SWITCH. Ensure ignition is off. Disconnect ECM harness connector. Turn ignition on. Check continuity between ground and ECM harness connector terminal No. 22 (Red/Green wire). Move shift lever through gears. Continuity should exist ONLY in Park and Neutral. If continuity is not as specified, go to next step. If continuity is as specified, system is functioning properly.
  2. Turn ignition off. Disconnect A/T control unit harness connector. Check continuity between ECM harness connector terminal No. 35 (Red/Green wire) and A/T control unit harness connector terminal No. 13 (Red/Green wire). Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair open Red/Green wire or connectors.
  3. Check inhibitor switch. See «INHIBITOR SWITCH»(ref-17826-S07518902692000122900000). Replace inhibitor switch if necessary. If switch is okay, check ECM and A/T control unit harness and connectors for pushed-out, bent, damaged or corroded terminals. Repair or replace harness or connectors as necessary.

NEUTRAL POSITION SWITCH SYSTEM TEST

  1. Disconnect neutral position switch 2-pin harness connector located on top of transmission extension housing. Check continuity between ground and Black wire of neutral position switch 2-pin harness connector. 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 ECM harness connector. Check continuity between ECM terminal No. 22 (Green/Orange wire) and neutral position switch 4-pin harness connector Green/Orange wire. Continuity should exist. If continuity exists, go to next step. If continuity does not exist, check harness and connectors between ECM and switch.
  3. Check neutral position switch. See «NEUTRAL POSITION»(ref-17826-S05141733162000122900000) SWITCH. Replace switch if necessary. If switch is okay, disconnect and inspect harness and connectors for pushed-out, bent, damaged or corroded terminals. Repair harness or connectors as necessary.

POWER STEERING OIL PRESSURE SWITCH SYSTEM TEST

  1. Start engine and bring to operating temperature. Measure voltage between specified ECM harness connector terminal and ground. See «POWER STEERING OIL PRESSURE SWITCH SYSTEM TEST»(ref-17826-S23376061182000122900000) table. Turn steering wheel quickly; approximately zero volts should be present. When steering wheel is not being turned, 5 volts should be present. If voltage is not as specified, go to next step. If voltage is as specified, system is functioning properly.
  2. Turn ignition off. Disconnect and inspect power steering oil pressure switch harness connector for pushed-out, bent, damaged or corroded terminals. Repair connector as necessary. Check continuity between power steering oil pressure switch harness connector Black wire and ground. Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair open Black wire or connectors.
  3. Check continuity between ECM harness connector terminal and power steering oil pressure switch harness connector. See «POWER STEERING OIL PRESSURE SWITCH SYSTEM TEST»(ref-17826-S23376061182000122900000) table. Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair open harness between ECM and switch.
  4. Check power steering oil pressure switch. See POWER STEERING OIL PRESSURE SWITCH. Replace switch if necessary. If switch is okay, check harness and connectors for pushed-out, bent, damaged or corroded terminals. Repair harness or connectors as necessary. POWER STEERING OIL PRESSURE SWITCH SYSTEM TEST Application Terminal No. (Wire Color) 240SX 25 (Purple/White)
  5. Start engine and bring to operating temperature. Measure voltage between ECM 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.
  6. Stop engine. Disconnect Idle Air Control Valve-Fast Idle Control Device (IACV-FICD) solenoid valve-2. Turn ignition on. Check voltage between ground and IACV-FICD solenoid valve-2 terminal No. 1 (Red/Yellow wire).
  7. Battery voltage should be present. If battery voltage is present, go to step 4). If battery voltage is not present, check 10-amp fuse, harness and connectors between IACV-FICD solenoid valve-2 and fuse.
  8. Turn ignition off. Disconnect power steering oil pressure switch harness connector. Check continuity between IACV-FICD solenoid valve-2 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 Green wire or connectors.
  9. Turn ignition off. Disconnect power steering oil pressure switch harness connector. 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.
  10. Disconnect and inspect ECM harness connector. Check continuity between ECM 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.
  11. Check power steering pressure switch. See procedures under «POWER STEERING OIL PRESSURE SWITCH»(ref-17826-S16481658922000122900000). 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.

FUEL PUMP SYSTEM TEST

  1. Turn ignition on. With fingers, pinch fuel feed hose at fuel filter. Fuel pressure pulsation should be felt for 5 seconds after ignition is turned on. If pulsation is not felt, go to next step. If pulsation is felt, system is functioning properly.
  2. Turn ignition off. Disconnect fuel pump relay. Fuel pump relay is located in fuse box next to battery. Turn ignition on. Measure voltage between ground and fuel pump relay harness connector terminals No. 1 and 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 15-amp fuse and harness continuity 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 checks. If continuity exists in both checks, go to next step. If continuity does not exist, repair appropriate harness or connectors.
  4. Ensure ignition is off. Disconnect ECM harness connector. ECM is located behind passenger's kick panel. Check continuity between ECM harness connector terminal No. 8 (Black/Pink wire) and fuel pump relay harness connector No. 2 (Black/Pink wire). Continuity should exist. If continuity does not exist, check harness and connectors between ECM and relay. Repair harness and connectors as necessary.
  5. If continuity exists, check fuel pump relay. See «RELAYS»(ref-17826-S11007097382000122900000) under RELAYS & SOLENOIDS. If relay is okay, check fuel pump. See «FUEL PUMP»(ref-17826-S33176450862000122900000). If fuel pump relay and fuel pump are okay, disconnect and inspect harness and connectors for pushed-out, bent, damaged or corroded terminals. Repair harness or connectors as necessary.

FUEL INJECTOR SYSTEM TEST

  1. With engine running, listen for clicking sound at each injector. If clicking sound is present at each injector, system is functioning properly. If clicking sound is not present, go to next step.
  2. Turn ignition off. Disconnect injector harness connector(s). Turn ignition on. Measure voltage between ground and injector harness connector Red wires (Black/Red wire on injector No. 1). Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, check 30-amp fusible link and ignition switch. If fusible link and ignition switch are okay, repair or replace harness or connectors.
  3. Ensure ignition is off. Disconnect ECM harness connector. ECM is located behind passenger's kick panel. Check continuity between ECM harness connector terminals No. 102 (White/Black wire), No. 104 (Green/Black wire), No. 107 (Yellow/Black wire), and No. 109 (Blue/Black wire) and corresponding fuel injector harness connector wire color. Continuity should exist.
  4. If no continuity, repair or replace harness or connectors. If continuity exists, check fuel injector. See «FUEL INJECTOR»(ref-17826-S35638483612000122900000). If fuel injector is okay, check ECM terminals, harness and connector terminals for damage or corrosion. Repair or replace as necessary.

AIR REGULATOR SYSTEM TEST

  1. Turn ignition on. Pinch fuel feed hose with fingers to feel fuel pulsations or listen for fuel pump operating sound. Fuel pump should operate for 5 seconds after ignition is turned on. If fuel pump does not operate, see «FUEL PUMP SYSTEM TEST»(ref-17826-S14828963972000122900000). If fuel pump operates, go to next step.
  2. Turn ignition off. Disconnect air regulator harness connector. Turn ignition on. Measure voltage between ground and air regulator harness connector Black/Red wire.
  3. Battery voltage should be present for 5 seconds after ignition is turned on. If voltage is as specified, go to next step. If voltage is not as specified, check continuity of Black/Red wire between air regulator harness connector and fuel pump relay. Repair or replace harness or connectors as necessary. If continuity is okay, check fuel pump relay. See «RELAYS»(ref-17826-S11007097382000122900000) under RELAYS & SOLENOIDS.
  4. Turn ignition off. Check continuity between ground and air regulator harness connector Blue/White wire. Continuity should exist. If continuity exists, check air regulator. See «AIR REGULATOR»(ref-17826-S37212075962000122900000). If continuity does not exist, repair open Blue/White wire.

AUXILIARY AIR CONTROL (AAC) VALVE SYSTEM TEST

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

FAST IDLE CONTROL DEVICE (FICD) SYSTEM TEST

  1. Start engine and warm to operating temperature. Check idle speed. Adjust idle speed if necessary. See the «ADJUSTMENTS»(ref-17823) 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 (engine) off. Disconnect FICD solenoid sub-harness connector. Start engine and let it idle. Measure voltage between ground and FICD sub-harness connector terminal Blue/Red (or Red) wire. Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, repair open harness or connectors between fuse, A/C relay, and FICD solenoid.
  4. Turn ignition off. Disconnect FICD solenoid sub-harness connector. Check continuity between ground and FICD solenoid sub-harness connector Black wire. Continuity should exist. If continuity exists, go to next step. If continuity does not exist, check diode and ambient switch or repair open Black wire or connectors.
  5. Check FICD solenoid. See «FAST IDLE CONTROL DEVICE (FICD)»(ref-17826-S07858032162000122900000) SOLENOID. If FICD solenoid is okay, check ECM terminals, harness, and connector terminals for pushed-out, damaged, or corroded terminals. Repair or replace as necessary.

START SIGNAL SYSTEM TEST

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

RADIATOR (COOLING) FAN CONTROL TEST

WARNINGBe careful not to overheat engine during radiator fan control test.
  1. Start engine and warm to operating temperature. Set temperature lever to full cold. Turn A/C switch on. Turn blower fan switch on. Run engine at idle with A/C on for several minutes. Ensure radiator fan operates. If fan does not operate at low speed, go to «RADIATOR (COOLING) FAN LOW SPEED CONTROL TEST»(ref-17826-S39628785092000122900000). If radiator fan operates at low speed, go to next step.
  2. Turn A/C switch and blower fan switch off. Turn ignition off. Disconnect engine coolant temperature sensor harness connector. Connect a 150-ohm resistor to engine coolant temperature sensor harness connector. Start engine and ensure radiator fan operates at high speed. If radiator fan does not operate at high speed, go to «RADIATOR (COOLING) FAN HIGH SPEED CONTROL TEST»(ref-17826-S19110751342000122900000). If radiator fan operates at high speed, system is functioning properly.

RADIATOR (COOLING) FAN LOW SPEED CONTROL TEST

  1. Turn ignition off. Disconnect radiator fan relay No. 2. Turn ignition on. Measure voltage between ground and radiator fan relay No. 2 harness connector terminals No. 2 (Blue/Orange wire) and No. 5 (Black/White wire). Battery voltage should be present. If battery voltage is present, go to step 3).
  2. If battery voltage is not present, check 7.5-amp fuse and 30-amp fusible link. Replace fuse or fusible link as necessary. If fuse and fusible links are okay, repair open harness or connectors between relay and ignition switch or battery.
  3. Turn ignition off. Disconnect radiator fan motor and radiator fan relay No. 2 harness connectors. Check continuity between radiator fan motor harness connector terminal No. 1 (White/Red wire) and radiator fan relay No. 2 harness connector terminal No. 3 (White/Red wire).
  4. Also check continuity between radiator fan motor harness connector terminals No. 3 and 4 (Black wires) and ground. Continuity should exist in all checks. If continuity exists in all checks, go to next step. If continuity does not exist in any check, repair open harness or connector.
  5. Disconnect ECM harness connector. ECM is located on right kick panel. Check continuity between ECM harness connector terminal No. 14 (Light Green wire) and radiator fan relay No. 2 harness connector terminal No. 1 (Light Green wire). Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair open harness or connectors.
  6. Check radiator fan relay No. 2. See «RELAYS»(ref-17826-S11007097382000122900000) under RELAYS & SOLENOIDS. Replace relay as necessary. If relay is okay, check fan motor. See «RADIATOR FAN MOTOR TEST»(ref-17826-S37714291982000122900000). Replace motor as necessary. If fan motor is okay, check ECM terminals, harness, and connector terminals for damage, corrosion or improper connection. Repair or replace as necessary.

RADIATOR (COOLING) FAN HIGH SPEED CONTROL TEST

  1. Turn ignition off. Disconnect radiator fan relay No. 1. Turn ignition on. Measure voltage between ground and radiator fan relay No. 1 harness connector terminals No. 2 (Blue/Orange wire) and No. 5 (Black/White wire). Battery voltage should be present. If battery voltage is present, go to step 3).
  2. If battery voltage is not present, check 7.5-amp fuse and 30-amp fusible link. Replace fuse or fusible link as necessary. If fuse and fusible link are okay, repair open harness or connectors between relay and ignition switch or battery.
  3. Turn ignition off. Disconnect radiator fan motor and radiator fan relay No. 1 harness connectors. Check continuity between radiator fan motor harness connector terminal No. 2 (Brown/White wire) and radiator fan relay No. 1 harness connector terminal No. 3 (Brown/White wire).
  4. Also check continuity between radiator fan motor harness connector terminals No. 3 and 4 (Black wires) and ground. Continuity should exist in all checks. If continuity exists in all checks, go to next step. If continuity does not exist in any check, repair open harness or connector.
  5. Disconnect ECM harness connector. ECM is located on right kick panel. Check continuity between ECM harness connector terminal No. 13 (Orange/Blue wire) and radiator fan relay No. 1 harness connector terminal No. 1 (Orange/Blue wire). Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair open harness or connectors.
  6. Check radiator fan relay No. 1. See «RELAYS»(ref-17826-S11007097382000122900000) under RELAYS & SOLENOIDS. Replace relay as necessary. If relay is okay, check fan motor. See «RADIATOR FAN MOTOR TEST»(ref-17826-S37714291982000122900000). Replace motor as necessary. If fan motor is okay, check ECM terminals, harness, and connector terminals for damage, corrosion or improper connection. Repair or replace as necessary.

RADIATOR FAN MOTOR TEST

Disconnect fan motor harness connector(s). Apply battery across fan motor terminals and observe motor operation. (Scheme 66) See FAN MOTOR OPERATION TEST table. If motor does not operate as indicated, replace motor.

Motor SpeedBattery Positive (+)Battery Negative (-)
Low"a""d"
High"a" & "b""c" & "d"

FAN MOTOR OPERATION TEST

Scheme 66

Scheme 66
Scheme 66

See also:
• WIRING DIAGRAMS

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