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Nissan 240sx S13 Engine Performance System and Component Testing

Nissan 240sx S13



NOTE: Testing individual components does not isolate shorts or opens. Perform all voltage tests with a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless stated otherwise in test procedure. Use ohmmeter to isolate wiring harness shorts or opens.

AIR INDUCTION SYSTEMS


SWIRL CONTROL VALVE

System Test
1. Start engine and bring to normal operating temperature. Turn ignition off. After a few seconds, disconnect vacuum hose to swirl control valve actuator. Actuator is located near flywheel end of intake manifold. Restart engine and check vacuum at disconnected hose.
2. Vacuum should exist at less than 2400 RPM and not exist at more than 2400 RPM. If vacuum does not exist as specified, leave engine running and go to next step. If vacuum exists as specified, system is functioning properly at this time.
3. Measure voltage between ECM terminal No. 25 (Gray wire) and ground. Zero volts should exist at less than 2400 RPM and battery voltage should exist at more than 2400 RPM.
4. If voltage is as specified, check vacuum hose and swirl control valve for clogging, cracks and proper connection and repair as necessary. If voltage is not as specified, turn ignition off. Disconnect and inspect swirl control valve solenoid connector, located rear of cylinder head. Repair connector as necessary.
5. Turn ignition on. Measure voltage between solenoid connector Brown wire and ground. Battery voltage should exist. If battery voltage exists, go to next step. If battery voltage does not exist, check harness, connectors and fuse. Repair as necessary.
6. Turn ignition off. Disconnect and inspect ECM harness connector for pushed-out, bent, damaged or corroded terminals. Repair connector as necessary. Check continuity of Gray wire between ECM terminal No. 25 and solenoid harness connector. Continuity should exist. If continuity does not exist, repair harness or connector as necessary. If continuity exists, check operation of swirl control valve solenoid.

Actuator
Disconnect vacuum hose from actuator, located near flywheel end of intake manifold. Apply and release vacuum at actuator diaphragm. Replace actuator if rod does not move.

NOTE: On some swirl control valve solenoids, port "C" may be a vent that is capped with a filter. Also, if solenoid does not respond as specified, perform test again, considering port "A" as port "B" and vice versa.

Control Solenoid
1. Disconnect vacuum lines and electrical connector from solenoid, located near flywheel end of cylinder head. Remove solenoid. Apply vacuum to port "B" of solenoid. See Fig. 13 . Vacuum should now be available at port "C", but not at port "A".
2. Apply battery voltage across solenoid connector terminals. Vacuum should now be available at port "A", but not at port "C". Replace solenoid if it does not operate as specified.

COMPUTERIZED ENGINE CONTROLS

Fig. 1: View Of ECM Harness Connectors (240SX)
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Fig. 2: ECM Relay Harness Connector Terminal ID (240SX)
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ECM POWER AND GROUND CIRCUITS

1. Turn ignition on. Measure voltage between ground and ECM harness connector terminals No. 38 (Black/White wire) and No. 47 (Black/White wire). See Fig. 1 . ECM is located behind right front kick panel. Battery voltage should be present. If battery voltage is present, go to step 3). If battery voltage is not present, go to next step.
2. Turn ignition off. Disconnect ECM harness connector. Check continuity between ground and ECM harness connector terminals No. 6 (Black wire), No. 13 (Black wire), No. 107 (Black wire), No. 108 (Black wire) and No. 116 (Black wire). Continuity should exist. If continuity does not exist, repair harness or connectors. If continuity exists, check ECM pin terminals and ECM harness connector terminals for damage or corrosion.
3. Turn ignition off. Disconnect ECM harness connector. Disconnect ECM (ECCS) relay. Relay is located in relay box behind battery. Check continuity between ECM harness connector terminals No. 38 (Black/White wire) and No. 47 (Black/White wire) and ECM relay connector terminal No. 3 (Black/White wire). See Fig. 2 . Continuity should exist. If continuity exists, go to next step. If continuity does not exist, check harness and connectors between ECM and ECM relay.
4. Measure voltage between ground and ECM relay harness connector terminals No. 1 (Red wire) and No. 5 (Red wire). See Fig. 2 . Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, check Brown fusible link. Check harness and connectors between ECM relay and battery.
5. Check voltage between ground and ECM harness connector terminal No. 46 (Red wire). Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, check harness and connectors. Check Brown fusible link. Check harness between ECM and battery.
6. Check continuity between ground and ECM harness connector terminals No. 39 (Black wire) and No. 48 (Black wire). Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair open in harness or connectors.
7. Check continuity between ECM harness connector terminal No. 4 (Red/Black wire) and ECM relay harness connector terminal No. 2 (Red/Black wire). See Fig. 2 . Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair open in harness between ECM harness connector and ECM relay harness connector.
8. Turn ignition on. Measure voltage between ground and ECM harness connector terminal No. 36 (Black/Red wire). Battery voltage should be present. If battery voltage is present, check ECM relay. If relay is okay, check ECM pin terminals and ECM harness connector terminals for damage or corrosion. If battery voltage is not present, check harness and connectors between ECM and ignition switch.


ENGINE SENSORS AND SWITCHES


MASS AIRFLOW SENSOR

Faults in mass airflow sensor circuit may set Code 12.

1. To test airflow sensor, warm engine to operating temperature. Pull rubber protector away from mass airflow sensor connector so terminals can be backprobed. At mass airflow sensor connector, measure voltage at White wire.
2. If voltage is not as specified in MASS AIRFLOW SENSOR VOLTAGE TEST table, check for dust or foreign material in hot wire air passage of mass airflow sensor. If air passage is okay, replace mass airflow sensor.

MASS AIRFLOW SENSOR VOLTAGE TEST (Values are approximate and vary with engine RPM.)


CRANKSHAFT POSITION SENSOR IS PART OF DISTRIBUTOR.

1. To test crankshaft position sensor, remove crankshaft position sensor (or distributor). Leave wiring harness connected. On vehicles with distributor, disconnect secondary coil wire from distributor cap, and then connect wire to ground. On all vehicles, turn ignition on.
2. Connect logic probe or DVOM with an analog bar graph function to ground. While slowly rotating sensor shaft by hand, backprobe specified wire terminals of sensor connector. See CRANKSHAFT POSITION SENSOR VOLTAGE TEST table.
3. If voltage does not fluctuate between 0 and 5 volts, check for damaged or dirty signal plate in crankshaft position sensor, and for shorted or open harness. If harness and signal plate are okay, replace crankshaft position sensor.

NOTE: It is possible to measure crankshaft position sensor voltage with a conventional DVOM without bar graph function; however, it may be difficult to determine peak voltage signal due to averaging of signal.

CRANKSHAFT POSITION SENSOR VOLTAGE TEST (This procedure may cause Codes 11 and/or 21 to set. Erase codes when procedure is complete.)


KNOCK (DETONATION) SENSOR

To test sensor, disconnect sensor connector. Check continuity between ground and sensor connector terminal. If there is no continuity, replace sensor. Check detonation sensor shield ground wire for continuity to ground. Ensure detonation sensor wire is not routed near spark plug wires or high-output electrical accessories. Discard any knock sensor which has been dropped or
undergone shocks.

DETONATION SENSOR LOCATION


ENGINE (COOLANT) TEMPERATURE SENSOR

Faults in engine (coolant) temperature sensor circuit may set Code 13.

To test sensor, disconnect sensor connector. Measure resistance across sensor connector terminals. If resistance is not as specified in ENGINE (COOLANT) TEMPERATURE SENSOR RESISTANCE table, replace sensor.

ENGINE (COOLANT) TEMPERATURE SENSOR LOCATION


ENGINE (COOLANT) TEMPERATURE SENSOR RESISTANCE


NOTE: Oxygen sensor with a heater element is identified by 3-wire connector.

OXYGEN SENSOR (O2)

Faults in oxygen sensor circuit may set Code 33.

To test HEATER element of Heated Oxygen Sensor (HO2S), check resistance between outer 2 terminals of 3-wire connector. If resistance is not 3-1000 ohms, replace sensor. EXHAUST GAS TEMPERATURE SENSOR (CALIFORNIA) Faults in exhaust gas temperature sensor circuit may set Code 35. To test sensor, place sensor in boiling water at 212°F (100°C). Resistance at 212°F (100°C) should be 76,770-93,830 ohms. As temperature increases, sensor resistance should decrease. If resistance is not as specified, replace sensor.

INHIBITOR SWITCH TEST

1. Disconnect and inspect inhibitor switch 8-pin and 2-pin harness connectors for pushed-out, bent, damaged or corroded terminals. Repair connector(s) as necessary. Connectors are located on side of transmission. Check continuity across terminals of inhibitor switch 2-pin connector. Continuity should exist ONLY in Park and Neutral. If continuity exists in any other position, replace inhibitor switch.
2. Using INHIBITOR SWITCH CONTINUITY table, place shift lever in indicated position. Check continuity between terminals of inhibitor switch 8-pin connector listed in table. See Fig. 3 . If switch does not function as indicated, replace switch.

INHIBITOR SWITCH CONTINUITY


Fig. 3: Inhibitor Switch Connector Terminal ID (240SX)
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INHIBITOR SWITCH SYSTEM TEST

1. Ensure inhibitor switch functions properly. Ensure ignition is off. Disconnect and inspect ECM harness connector for pushed-out, bent, damaged or corroded terminals. Repair connector as necessary. Turn ignition on. Check continuity between ECM harness connector terminal No. 35 (Green/Orange wire) and ground. Move shift lever through gears. Continuity should exist ONLY in Park and Neutral. If continuity is not as specified, go to next step. If continuity is as specified, system is functioning properly.
2. Turn ignition off. Disconnect and inspect AT control harness connector for pushed-out, bent, damaged or corroded terminals. Repair connector as necessary. Check continuity between ECM harness connector terminal No. 35 (Green/Orange wire) and AT control unit harness connector terminal No. 13 (Green/Orange wire). Continuity should exist. If continuity does not exist, repair open in Green/Orange wire. If continuity does not exist, recheck ECM and AT control unit harness connectors and repair as necessary.

NEUTRAL POSITION SWITCH SYSTEM TEST
1. Turn ignition off. Disconnect and inspect ECM harness connector for pushed-out, bent, damaged or corroded terminals. Repair connector as necessary. Check continuity between ECM harness connector terminal No. 35 (Green/Orange wire) and ground. Move shift lever through gears. Continuity should exist ONLY in Neutral. If continuity is not as specified, go to next step. If continuity is as specified, system is functioning properly.
2. Disconnect and inspect Neutral position switch 2-pin harness connector for pushed-out, bent, damaged or corroded terminals. Connector is located on transmission tail shaft housing. Repair connector as necessary. Check continuity between Black wire of Neutral position switch 2-pin harness connector and ground. Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair open in Black wire or connectors.
3. Check continuity between ECM harness connector terminal No. 35 (Green/Orange wire) and Green/Orange wire of Neutral position switch 2-pin harness connector. Continuity should exist. If
continuity exists, check Neutral position switch. If continuity does not exist, check harness and connectors for open. Repair as necessary.
NEUTRAL POSITION SWITCH TEST Disconnect Neutral position switch 2-pin harness connector located on top of transmission tail shaft housing. Check continuity between Neutral position switch 2-pin connector terminals. Continuity should exist with transmission in Neutral. Continuity should not exist in any other position. If Neutral position switch does not function as described, replace switch.

POWER STEERING PRESSURE SWITCH SYSTEM TEST

1. Start engine and bring to operating temperature. Measure voltage between ECM harness connector terminal No. 43 and ground. For wire color, see ECM CONNECTOR TERMINAL NO. 43 WIRE COLOR table. Turn steering wheel quickly; approximately zero volts should be present. When steering wheel is not being turned, 7-9 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 pressure switch harness connector for pushedout, bent, damaged or corroded terminals. Repair connector as necessary. Check continuity between power steering 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 in Black wire or connectors.
3. Disconnect and inspect ECM harness connector for pushed-out, bent, damaged or corroded terminals. Repair connector as necessary. Check continuity between ECM harness connector terminal No. 43 and appropriate wire at power steering pressure switch harness connector. Continuity should exist. If continuity exists, check power steering pressure switch. If continuity does not exist, repair open in appropriate wire or connectors.

ECM CONNECTOR TERMINAL NO. 43 WIRE COLOR


POWER STEERING PRESSURE SWITCH TEST

Disconnect switch connector. Switch is attached to power steering high pressure hose. Check resistance between switch connector terminals. Start engine. Replace switch if continuity is not as specified in POWER STEERING PRESSURE SWITCH table.

POWER STEERING PRESSURE SWITCH


THROTTLE POSITION SENSOR (TPS)

Faults in TPS circuit may set Code 43.

1) To test TPS, disconnect TPS connector. TPS is mounted on side of throttle body. While opening and closing throttle, check resistance across specified wire terminals of TPS connector. If resistance value does not change smoothly, replace TPS.
2) If resistance is not as specified, check harness. If harness is okay, adjust TPS. If resistance is still not as specified after adjustment, replace TPS.

THROTTLE POSITION SENSOR RESISTANCE TEST


VSS

Faults in vehicle speed sensor circuit may set Code 14.

To test sensor, remove vehicle speed sensor from transmission. While rotating sensor shaft by hand, check AC voltage across sensor connector terminals. If about .5 volt AC is not present, replace sensor.


RELAYS AND SOLENOIDS


RELAYS
A variety of relays are used and can be tested 2 different ways. The following relays can be tested using an ohmmeter and remotely supplied power and ground circuits:


Safety relays can be tested using an ohmmeter, voltmeter and remote-ly supplied power and ground circuits. All testing procedures require proper identification of relay internals.

Except Safety Relay
Turn ignition on. Ensure power to relay exists. Turn ignition off. Disconnect connector from relay being tested. Using ohmmeter, check for relay winding continuity across appropriate relay terminals. Energize relay and check continuity of relay output circuit.

EXAMPLE: Maxima Fuel Pump Relay
1. Turn ignition on. Ensure battery voltage exists at Blue wire of fuel pump relay. See Fig. 4 . If battery voltage is not present at Blue wire, check for a blown 10-amp power fuse or an open circuit between fuse and relay.
2. Turn ignition off. Unplug fuel pump relay. Check for continuity across Blue wire and Blue/White wire terminals. If continuity does not exist, relay is defective. If continuity exists, connect ohmmeter leads across Orange wire and Black wire terminals. Energize relay by applying battery voltage to Blue wire terminal and ground to Blue/White wire terminal. Ensure continuity exists while relay is energized.

Fig. 4: Testing Maxima Fuel Pump and Safety Relays
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Safety Relay
Turn ignition on and ensure power to relay exists. Turn ignition off. Disconnect safety relay connector. Using an ohmmeter, check one-way internal diode in safety relay by checking for continuity in both directions. Energize relay and check for voltage signal on relay output circuit.

EXAMPLE: Maxima Safety Relay
1. Turn ignition on. Using a voltmeter, check for battery voltage at Blue wire of safety relay. See Fig. 4 . If voltage is not present, check for blown 10-amp fuse or open circuit between fuse and relay.
2. Turn ignition off. Disconnect safety relay connector. Using ohmmeter, check for continuity across relay's Black wire and Blue wire terminals. Reverse ohmmeter leads. Continuity should only exist in one direction. Connect voltmeter positive lead to Red/Blue wire terminal. Connect negative voltmeter lead to Black wire terminal. Apply battery voltage to Blue wire terminal and ground to Black wire terminal. Voltmeter should show battery voltage while relay is energized.



FUEL SYSTEM


FUEL DELIVERY

Start Signal
If ECM receives incorrect start (cranking) signal, fuel delivery system may not operate properly.

Fig. 5: Testing Fuel Pump System (240SX)
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Fuel Pump System Test
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 in fuse box next to battery. Turn ignition on. Measure voltage between ground and fuel pump relay harness connector terminals No. 1 (Black/White wire) and No. 5 (Black/White wire). For terminal identification, see Fig. 5 . Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, check 10-amp fuse in main fuse box. Check harness continuity between fuse and fuel pump relay. Repair or replace as necessary.
3. Turn ignition off. Disconnect fuel pump harness connector, located under rear seat. Check continuity between ground and fuel pump harness connector terminal "a" (Black wire). Check continuity between fuel pump relay harness connector terminal No. 3 (Black/Yellow wire) and fuel pump harness connector terminal "c" (Black/Yellow wire). For terminal identification, see Fig. 5 . 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. 104 (Black/Pink wire) and fuel pump relay harness connector No. 2 (Black/Pink wire). See Fig. 1 and Fig. 5 . Continuity should exist. If continuity exists, check fuel pump relay. If relay is okay, check fuel pump. If continuity does not exist, check harness between ECM and relay. Repair harness and connectors as necessary.

Fuel Pump Test
To test fuel pump, disconnect fuel pump connector, under vehicle body. At fuel pump connector, check resistance between wire terminals. If resistance is not as specified, replace fuel pump.

FUEL PUMP RESISTANCE TEST


FUEL CONTROL

Start Signal
If ECM receives incorrect start (cranking) signal, fuel control system may not operate properly.

Feedback System
Ensure ignition timing and idle speed are adjusted. Warm engine to operating temperature. Run engine unloaded at 2000 RPM for 2 minutes. Enter self-diagnostic Mode II. If Red LED on ECM (or CHECK ENGINE light) does not flash at least 5 times in a 10-second period, perform IDLE MIXTURE adjustment procedure.

Fuel Injector System Test
1. With engine running, measure voltage between ground and ECM harness connector terminals No. 101 (White/Black wire), No. 103 (Green/Black wire), No. 110 (Yellow/Black wire), and No. 112 (Blue/Black wire). ECM is located behind passenger side kick panel. See Fig. 1 . Battery voltage should be present. If battery voltage is not present, go to next step. If battery voltage is present, system is functioning properly.
2. Turn ignition off. Disconnect each injector harness connector. Disconnect ECM harness connector. Measure voltage between ground and each injector harness connector Red wire. Measure voltage between ground and ECM harness connector terminal No. 109 (Red wire). Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, check Brown fusible link located in fuse and fusible link box behind battery. If fusible is okay, repair or replace harness or connectors.
3. Check continuity between ECM harness connector terminals No. 101 (White/Black wire), No. 103 (Green/Black wire), No. 110 (Yellow/Black wire), and No. 112 (Blue/Black wire) and corresponding injector harness connector wire color. Continuity should exist. If continuity exists, check injector. If injector is okay, check ECM pin terminals and ECM harness connector
terminals for damage or corrosion. Repair or replace as necessary. If continuity does not exist, repair or
replace harness or connectors.

Fuel Injector Test
Check resistance across injector connector terminals. If resistance is not as specified in INJECTOR RESISTANCE SPECIFICATIONS table, replace injector. If resistance is okay, remove injector. If nozzle is clogged, replace injector.

INJECTOR RESISTANCE SPECIFICATIONS



IDLE CONTROL SYSTEM


START SIGNAL

If ECM receives incorrect start (cranking) signal, idle control system may not operate properly.

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 operates, go to next step.
2. Turn ignition off. Disconnect air regulator harness connector. Measure voltage between ground and air regulator harness connector Black/Pink wire.
3. Turn ignition on. 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/Pink 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.
4. Turn ignition off. Check continuity between ground and air regulator harness connector Black wire. Continuity should exist. If continuity exists, check air regulator. If continuity does not exist, repair open in Black wire.

AIR REGULATOR TEST
Measure resistance across air regulator connector terminals. If resistance is not about 70-80 ohms, replace air regulator. If resistance is okay, ensure air passage is not obstructed.

AUXILIARY AIR CONTROL (AAC) VALVE SYSTEM TEST
1. Start engine and bring to operating temperature. Check idle speed. Adjust idle speed if necessary.
2. Check for stored codes. If Code 43 is present, repair cause of Code 43 before continuing. If Code 43 is not present, disconnect throttle position sensor harness connector. If idle speed does not drop, go to next step. If idle speed drops, system is functioning properly.
3. Turn ignition off. Disconnect AAC valve harness connector. Turn ignition on. Measure voltage between ground and AAC valve harness connector Red/Green 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 75-amp fusible link located in engine compartment fuse box. If fuse and fusible link are okay, repair or replace harness or connectors between AAC valve and fuse box.
4. Turn ignition off. Disconnect ECM harness connector. Check continuity between ECM harness connector terminal No. 113 (Sky Blue wire) and AAC valve harness connector Red/White wire. Continuity should exist. If continuity exists, check AAC valve. If AAC valve is okay, check ECM pin terminals and ECM harness connector terminals for damage or corrosion. Repair as necessary. If continuity does not exist, repair open in harness or connectors.

FAST IDLE CONTROL DEVICE (FICD) TEST
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.


IGNITION SYSTEMS


POWER TRANSISTOR

Fig. 6: Identifying Power Transistor Connector Terminals (240SX)
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START SIGNAL

Start Signal System Test
1. Locate ECM harness connector. ECM is located behind passenger side kick panel. Measure voltage between ground and ECM harness connector terminal No. 34 (Orange wire). See Fig. 1 . Turn ignition switch to START position. Battery voltage should be present in start position ONLY. Zero volts should be present in any other ignition switch position. If voltage is not as specified, go to next step. If voltage is as specified, system is functioning properly.
2. Turn ignition off. Disconnect ECM harness connector. Disconnect ignition switch harness connector. Check continuity between ECM harness connector terminal No. 34 (Orange wire) and ignition switch harness connector terminal "f" (Black/Yellow wire). For ignition switch connector identification, see Fig. 7 . Continuity should exist. If continuity exists, check ECM and ECM harness connector terminals for correct installation, damage or corrosion. Repair as necessary. If continuity does not exist, repair open in harness or connectors between ignition switch and ECM harness connector. Check 10-amp fuse located in fuse box under left instrument panel. Repair or replace as necessary.

Fig. 7: Testing Start Signal (240SX)
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TIMING CONTROL SYSTEMS

Timing Advance
Ignition timing advance is controlled by the ECM based upon sensor input signals. If timing problems are experienced, inspect input signals for proper operation. Inputs that affect timing include the following:


Detonation (Knock) Retard
Faults in detonation retard circuit may set Code 34.


EMISSION SYSTEMS AND SUB-SYSTEMS


CANISTER PURGE SYSTEM

Carbon Canister
Remove hoses from carbon canister. Blow air into canister ports as shown. See Fig. 8 . 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.

Fuel Vapor Check Valve
Disconnect hoses from fuel vapor check valve. Apply light air pressure to fitting on side of valve that leads to fuel tank. Resistance should be felt, but some air should flow out of fitting that leads to carbon canister. Apply light air pressure to fitting that leads to carbon canister. Air should flow freely through valve. If valve does not operate as described, replace valve.

Fig. 8: Testing Carbon Canister Purge Valves
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EXHAUST GAS RECIRCULATION (EGR)

Start Signal
If ECM receives an incorrect start (cranking) signal, EGR control solenoid may not operate properly.

EGR Function (California)
Faults in EGR function circuit may set Code 32.

EGR System Test (Non-California)
1. Start engine and bring to operating temperature. Using a mirror or finger, ensure EGR valve plunger moves up and down as engine is accelerated from idle to 2000 RPM and back to idle. If plunger does not move up and down, go to next step. If plunger moves up and down, system is functioning properly.
2. Disconnect vacuum hose from EGR valve. Vacuum should not be present at idle. Vacuum should be present at 2000 RPM. If vacuum is not present as described, go to next step. If vacuum is present as described, check EGR valve. Check EGR backpressure transducer. Replace malfunctioning components.
3. Measure voltage between ground and ECM harness connector terminal No. 105 (Light Green wire). See Fig. 1 . ECM is located under center of instrument panel (connector is behind passenger side kick panel). Start engine. At idle, zero volts should be present. At 2000 RPM, battery voltage should be present. If voltage is not as specified, go to next step. If voltage is as specified, check vacuum hose for clogging, cracks and proper connection. Replace hose as necessary.
4. Turn ignition off. Disconnect EGR and canister control solenoid harness connector. Solenoid is located near rear of cylinder head. Turn ignition on. Measure voltage between ground and EGR and canister control solenoid harness connector Brown wire. Battery voltage should be present. If battery voltage is present, go to step 6).
5. If battery voltage is not present, check 10-amp fuse located in relay box next to battery. Replace fuse if necessary. If fuse is okay, repair open in Brown wire between fuse and solenoid.
6. Turn ignition off. Disconnect ECM harness connector. Check continuity between ECM harness connector terminal No. 105 (Light Green wire) and EGR and canister control solenoid harness connector Light Green wire. Continuity should exist. If continuity exists, check solenoid valve. Replace solenoid as necessary. If solenoid is okay, check ECM and ECM harness connector for damage or improper connection. If continuity does not exist, repair open in Light Green wire.

EGR Backpressure Transducer (EGR-BPT)
Plug one port of EGR backpressure transducer (EGR-BPT) and apply vacuum to other port. See Fig. 9 and Fig. 10 . 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 valve.

Fig. 9: Cross-Sectional View Of EGR Backpressure Transducer (EGR-BPT)
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Fig. 10: Backpressure EGR System Diagram (240SX)
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Using a hand-held vacuum pump, apply vacuum to EGR valve diaphragm. See Fig. 11 . Replace EGR valve if pintle does not open.

Fig. 11: Cross-Sectional View Of Typical EGR Valve
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NOTE: On some EGR control solenoids, port "C" may be a vent that is capped with a filter. Also, if solenoid does not respond as specified, perform test again, considering port "A" as port "B" and vice versa.

EGR Control Solenoid
1. Disconnect vacuum lines and electrical connector from solenoid. Remove solenoid. Using hand-held vacuum pump, apply vacuum to port "B" of solenoid. See Fig. 13 . Vacuum should now be available at port "C", but not at port "A".
2. Apply battery voltage across solenoid connector terminals, ensuring polarity is correct to prevent solenoid damage. Vacuum should now be available at port "A", but not at port "C". Replace solenoid if it does not operate as specified.

PULSED SECONDARY AIR INJECTION (PAIR)

Pulsed Secondary Air Injection (PAIR) System Test
1. Start engine and warm to operating temperature. Run engine at approximately 2000 RPM for 2 minutes under no-load. Release accelerator pedal and let engine idle. Disconnect PAIR valve inlet hose (top hose). Listen to PAIR valve operating sound. With engine idling and during deceleration, PAIR valve should operate. When accelerator pedal is depressed, PAIR valve should not operate. If PAIR valve does not operate as described, go to next step. If PAIR valve operates as described, system is functioning properly.
2. Disconnect vacuum hose at PAIR valve. PAIR valve is located at left side of engine compartment, near brake master cylinder. With engine idling and during deceleration, vacuum should exist. When accelerator pedal is depressed, vacuum should not exist. If vacuum does not exist as described, go to next step. If vacuum exists as described, check PAIR valve.
3. Locate ECM harness connector. ECM is located behind passenger side kick panel. Measure voltage between ground and ECM harness connector terminal No. 102 (Pink wire). See Fig. 1 . With engine idling and during deceleration, zero volts should be present. When accelerator pedal is depressed, battery voltage should be present. If voltage is not as described, go to next step. If voltage is as described, check vacuum hose for clogging, cracks and proper connection.
4. Turn ignition off. Disconnect PAIR control solenoid harness connector. Solenoid is located next to PAIR valve. Turn ignition on. Measure voltage between ground and PAIR control 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 located in relay box next to battery. Replace fuse as necessary. If fuse is okay, repair open in Brown wire between PAIR control solenoid and fuse.
5. Turn ignition off. Disconnect ECM harness connector. Check continuity between ECM harness connector terminal No. 102 (Pink wire) and PAIR control solenoid harness connector Pink wire. Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair open in Pink wire between ECM and PAIR control solenoid.
6. Check PAIR control solenoid. Replace solenoid as necessary. If solenoid is okay, check ECM and ECM harness
connector terminals for damage, corrosion and proper connection. Repair or replace as necessary.

Pulsed Secondary Air Injection (PAIR) Valve Test
Apply vacuum to PAIR valve diaphragm. See Fig. 12 . Apply light air pressure to air cleaner side of PAIR valve. Air should flow toward exhaust manifold side. Air should NOT flow in opposite direction. If PAIR valve does not operate as described, replace valve.

Fig. 12: Typical Pulsed Secondary Air Injection Valve
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NOTE: On some Pulsed Secondary Air Injection (PAIR) control solenoids, port "C" may be a vent that is capped with a filter. Also, if solenoid does not respond as specified, perform test again, considering port "A" as port "B" and vice versa.

Pulsed Secondary Air Injection (PAIR) Control Solenoid Test
1. Disconnect vacuum lines and electrical connector from solenoid. Remove solenoid. Connect hand-held vacuum pump to vacuum port "B" of solenoid. See Fig. 13 . Apply vacuum. Vacuum should now be available at port "C", but not at port "A".
2. Apply battery voltage across solenoid connector terminals, ensuring polarity is correct to prevent solenoid damage. Vacuum should now be available at port "A", but not at port "C". Replace solenoid if it does not operate as specified.

Fig. 13: Typical Control Solenoid (EGR, PAIR, PRVR and SCV)
SystemComponent13

POSITIVE CRANKCASE VENTILATION (PCV)
With engine idling, disconnect ventilation hose from PCV valve. If a hissing noise and strong vacuum are not present at hose end, check hose and hose connections for leaks or obstructions. Repair or replace as necessary.

MISCELLANEOUS CONTROLS

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

CONDENSER COOLING FAN
The ECM controls condenser cooling fan based on vehicle speed, engine coolant temperature and AC switch position. Compare cooling fan operation with operation specified in AC SWITCH ON OR OFF table.

AC SWITCH ON OR OFF


Condenser (Cooling) Fan Control Test
1. Start engine and warm to operating temperature. Set temperature lever to full cold. Turn AC switch on. Turn fan switch on. Run engine at idle with AC on for several minutes. Ensure condenser fan operates. If fan does not operate, go to next step. If fan operates, system is functioning properly.
2. Turn AC and fan switches off. Turn ignition off. Disconnect condenser fan relay. See Fig. 14 and Fig. 15 . Turn ignition on. Measure voltage between ground and condenser fan relay harness connector terminals No. 2 (Blue/Orange wire) and No. 3 (Black/White wire). Battery voltage should be present. If battery voltage is present, go to step 4). If battery voltage is not present, go to next step.
3. Check Gray and Green fusible links located in fuse and relay box next to battery. Replace fusible links as necessary. Check 10-amp fuse located in fuse box under left side of instrument panel. Replace fuse as necessary. If fusible links and 10-amp fuse are okay, repair open in harness or connectors.
4. Turn ignition off. Disconnect condenser fan motor harness connector. Check continuity between condenser fan motor harness connector terminal "a" (Brown/White wire) and condenser fan relay harness connector terminal No. 5 (Brown/White wire). See Fig. 14 and Fig. 15 . Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair open in Brown/White wire.
5. Check continuity between ground and condenser fan motor harness connector terminal "b" (Black wire). See Fig. 14 and Fig. 15 . Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair open in Black wire.
6. Disconnect ECM harness connector. ECM is located behind passenger side kick panel. Check continuity between ECM harness connector terminal No. 9 (Orange/Blue wire) and condenser fan relay harness connector terminal No. 1 (Orange/Blue wire). See Fig. 1 and Fig. 14 -Fig. 15 . Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair open in Orange/Blue wire.
7. Check condenser fan relay. Replace relay as necessary. If relay is okay, check condenser fan motor. Replace fan motor as necessary. If fan motor is okay, inspect ECM and ECM harness connector terminals for damage, corrosion and improper connection. Repair as necessary.

Condenser Fan Motor Test
Apply battery voltage across fan motor connector terminals. Fan motor should operate. If fan motor does not operate, replace fan motor.

Fig. 14: Testing Condenser Fan Circuit - 1 Of 2 (240SX)
SystemComponent14
Fig. 15: Testing Condenser Fan Circuit - 2 Of 2 (240SX)
SystemComponent15
Radiator Fan Motor Test
Disconnect fan motor harness connector(s). Apply battery across fan motor terminals and observe motor operation. See Fig. 16 . If motor does not operate as indicated, replace motor.

FAN MOTOR OPERATION TEST

Motor Number

Fig. 16: Testing Radiator Fan Motors
SystemComponent16



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Nissan 240sx S13

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