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

Ground Circuits

1. Using an ohmmeter, check for continuity to ground on ECM terminals No. 10, 19, 39, 43, 50, 106, 112 and 118. (Scheme 20) Resistance should be zero ohms. If resistance is not zero ohms, repair open to ground.
2. Using a DVOM, touch negative lead of voltmeter to a good ground. Using positive lead of voltmeter, backprobe each ground terminal at ECM connector. With vehicle running, voltmeter should indicate less than one volt. If voltmeter reading is greater than one volt, check for open, corrosion or loose connection on ground lead.

Power Circuits

1. Turn ignition switch to ON position. Using a voltmeter, check for battery voltage between chassis ground and ECM terminals No. 38, 56 and 61. (Scheme 20) If battery voltage is not present, check fusible link and fuse "G".
2. Turn ignition switch to OFF position. Using a voltmeter, check for battery voltage between chassis ground and ECM power back-up terminals. If battery voltage is not present, check for overheated relays, fusible links and wiring.

Scheme 20

ENGINE SENSORS & SWITCHES

Note. For ECM connector terminal ID, see PIN VOLTAGE CHARTS article and the WIRING DIAGRAMS article.

CAMSHAFT POSITION SENSOR

1. Camshaft position sensor is located on engine front cover. Faults in camshaft position sensor circuit should set Diagnostic Trouble Code (DTC) PO340. To test system, see DTC P0340 - CAMSHAFT POSITION (CMP) SENSOR procedures in «TESTS W/CODES»(ref-17815) article.
2. To test camshaft position sensor, start and run engine at idle. Connect voltmeter to ground. Backprobe specified wire terminals of sensor connector. See «CAMSHAFT POSITION SENSOR VOLTAGE TEST»(ref-17816-S00416562812000122900000) table.
3. Voltage pulse signal should be approximately 2.7 volts. If voltage is not as specified, check for damaged or dirty signal plate in camshaft position sensor, and for shorted or open harness. If harness and signal plate are okay, replace camshaft position sensor.

CAMSHAFT POSITION SENSOR VOLTAGE TEST

CRANKSHAFT POSITION SENSOR (CKP)

Faults in CKP sensor or circuit should set a Diagnostic Trouble Code (DTC) P0335 or P01336. For testing procedure, refer to DTC P0O335 OR P1336 - CRANKSHAFT POSITION (CKP) SENSOR in the TESTS W/CODES article.

INHIBITOR SWITCH

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 top or on side of transaxle/transmission.
2. Using «INHIBITOR SWITCH CONTINUITY»(ref-17816-S13457952322000122900000) table, place shift lever in indicated position. Check continuity between terminals of inhibitor switch 8-pin and 2-pin connector listed in table. (Scheme 21) If switch does not function as indicated, replace switch.

INHIBITOR SWITCH CONTINUITY

Scheme 21

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 (KS) in the TESTS W/CODES article. To locate sensor, see KNOCK SENSOR LOCATION table.

KNOCK SENSOR LOCATION

ENGINE COOLANT TEMPERATURE (ECT) SENSOR

1. 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 the «TESTS W/CODES»(ref-17815) article.
2. To test sensor, disconnect sensor connector. See ENGINE COOLANT TEMPERATURE (ECT) SENSOR LOCATION table. Measure resistance across sensor connector terminals. See ENGINE COOLANT TEMPERATURE (ECT) SENSOR RESISTANCE table. If resistance is not as specified, replace sensor.

ENGINE COOLANT TEMPERATURE (ECT) SENSOR LOCATION

ENGINE (COOLANT) TEMPERATURE SENSOR RESISTANCE

EXHAUST GAS TEMPERATURE SENSOR

1. Faults in exhaust gas temperature sensor circuit should set DTC P1401. To test system, see DTC P1401 - EGR TEMPERATURE SENSOR diagnostic procedures in the «TESTS W/CODES»(ref-17815) article.
2. 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.

INTAKE AIR TEMPERATURE SENSOR

Faults in IAT sensor or circuit should set a Diagnostic Trouble Code (DTC) PO110. For testing procedure, refer to DTC P0110 - INTAKE AIR TEMPERATURE (IAT) SENSOR in the TESTS W/CODES article.

HEATED OXYGEN SENSOR (HO2S)

Faults in oxygen sensor circuit should set DTC P0130/P0135 (front), or DTC P0136/P0141 (rear). To test system, see diagnostic procedures in TESTS W/CODES article.

MASS AIRFLOW SENSOR

1. Faults in mass airflow sensor circuit shoule set Diagnostic Trouble Code (DTC) P0100. For testing procedure, refer to DTC P0100 - MASS AIRFLOW (MAF) SENSOR in the «TESTS W/CODES»(ref-17815) article.
2. To test mass 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 between ground and Orange wire.
3. 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 (1)

NEUTRAL POSITION SWITCH

Disconnect neutral position switch 2-pin harness connector located on top of transaxle. Check continuity between neutral position switch 2-pin connector terminals. Continuity should exist with transaxle in Neutral. Continuity should not exist in any other position. If neutral position switch does not function as described, replace switch.

POWER STEERING OIL PRESSURE SWITCH

Disconnect power steering oil pressure switch connector. Switch is attached to power steering high pressure hose. Start engine and check switch for continuity. Replace switch if continuity is not as specified in POWER STEERING OIL PRESSURE SWITCH table.

POWER STEERING OIL PRESSURE SWITCH

THROTTLE POSITION (TP) SENSOR

1. Faults in TP sensor circuit should set DTC P0120. To test system, see DTC P0120 - THROTTLE POSITION (TP) SENSOR diagnostic procedures in the «TESTS W/CODES»(ref-17815) article.
2. To test TP sensor, disconnect TP sensor connector. TP sensor is mounted on side of throttle body. While opening and closing throttle, check resistance across specified wire terminals of TP sensor connector. See THROTTLE POSITION SENSOR RESISTANCE TEST table.
3. If resistance is not as specified, check wiring harness. If no faults are found, adjust TP sensor. See «ADJUSTMENTS»(ref-17813) article. If resistance is still not as specified after adjustment, replace TP sensor.

THROTTLE POSITION SENSOR RESISTANCE TEST

VEHICLE SPEED SENSOR

1. Faults in vehicle speed sensor circuit should DTC P0500. To test system, see DTC P0500 - VEHICLE SPEED SENSOR (VSS) diagnostic procedures in the «TESTS W/CODES»(ref-17815) article.
2. To test sensor, remove vehicle speed sensor from transaxle/transmission. While rotating sensor shaft by hand, check AC voltage across sensor connector terminals. If about 0.5 volt AC is not present, replace sensor.

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

1. Electronic Control Module (ECM or ECCS) relay.
2. Fuel pump relay.
3. Main relay.
4. Radiator (cooling) fan relay.
5. Mixture heater relay.
6. Park/neutral (inhibitor) relay.

Safety relays can be tested using an ohmmeter, voltmeter and remotely supplied power and ground circuits. All testing procedures require proper identification of relay internal circuits. See the WIRING DIAGRAMS article.

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. See the WIRING DIAGRAMS article to identify proper relay terminals (wire colors) for testing. Energize relay and check continuity of relay output circuit.

EXAMPLE: Fuel Pump Relay (Maxima Shown)

1. Turn ignition on. Ensure battery voltage exists at Blue wire of fuel pump relay. (Scheme 22) 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.

Scheme 22

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: Safety Relay (Maxima Shown)

1. Turn ignition on. Using a voltmeter, check for battery voltage at Blue wire of safety relay. (Scheme 22) 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.

EGR Control Solenoid

See EXHAUST GAS RECIRCULATION (EGR) under EMISSION SYSTEMS & SUB-SYSTEMS.

EGR & Canister Control Solenoid

See EXHAUST GAS RECIRCULATION (EGR) under EMISSION SYSTEMS & SUB-SYSTEMS.

Fast Idle Control Device (FICD) Solenoid

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

Valve Timing Control (VTC) Solenoid

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.

FUEL DELIVERY

Note. For fuel system pressure testing, see FUEL PRESSURE under FUEL SYSTEM in the BASIC TESTING article. If ECM 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. 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 the BASIC TESTING article. If pressure is not as specified, replace fuel pressure regulator.

FUEL PUMP

To test fuel pump, disconnect fuel pump connector, accessible under rear seat. 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

FUEL INJECTOR

Disconnect fuel injector harness connector. 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

AUXILIARY AIR CONTROL (AAC) VALVE

Disconnect AAC valve harness connector. Check resistance between AAC valve connector Brown wire and Light Blue wire terminals, and between Brown wire terminal and Purple/White wire terminals. If resistance is not 50-100 ohms at 77°F (25°C), replace AAC valve.

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.

IGNITION SYSTEMS

Note. For basic ignition checks, see the BASIC TESTING article.

POWER TRANSISTOR

Note. The DVOM must have a diode check position and be able to measure up to 20 megohms to perform this test.

Disconnect power transistor 6-pin and 2-pin connectors. Check power transistor resistance between pin No. 8 (Blue wire) and pin No. 2 (Black wire). Resistance should be more than zero ohms. If resistance is incorrect, replace distributor.

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. See the PIN VOLTAGE CHARTS 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

Faults in knock sensor (detonation retard) circuit may set Code 34 or DTC P0325. To test system, see CODE 34 or DTC P0325 diagnostic procedures in the TESTS W/CODES article. To test knock (detonation) sensor, see ENGINE SENSORS & SWITCHES.

Carbon Canister

Remove hoses from carbon canister. Blow air into canister ports as shown. (Scheme 23) 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.

Scheme 23

EGR Backpressure Transducer (EGR-BPT) & EGR Canister Backpressure Transducer (EGRC-BPT) Valves

Plug one port of EGR-BPT (EGRC-BPT) valve and apply vacuum to other port. (Scheme 24) 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 (EGRC-BPT) valve.

Scheme 24

1. Disconnect vacuum lines and electrical connector from solenoid. Remove solenoid. Using hand-held vacuum pump, apply vacuum to port "A" of solenoid. (Scheme 25) Vacuum should now be available at port "C", but not at port "B".
2. Apply battery voltage across solenoid connector terminals. Apply vacuum to port "A" of solenoid. Vacuum should now be available at port "B", but not at port "C". Replace solenoid if it does not operate as specified.

1. Faults in EGR and canister control solenoid circuit may set Code 105 or DTC P1400. To test circuit, see CODE 105 or DTC P1400 diagnostic procedures in the «TESTS W/CODES»(ref-17815) article.
2. To test solenoid, disconnect vacuum lines and electrical connector from solenoid. Remove solenoid. Using hand-held vacuum pump, apply vacuum to port "A" of solenoid. (Scheme 25) Vacuum should now be available at port "C", but not at port "B".
3. Apply battery voltage across solenoid connector terminals. Apply vacuum to port "A" of solenoid. Vacuum should now be available at port "B", but not at port "C". Replace solenoid if it does not operate as specified.

Scheme 25

EGR Function

Faults in EGR function circuit may set Code 32 or DTC P0400. To test function, see CODE 32 or DTC P0400 diagnostic procedures in the TESTS W/CODES article.

EGRC-BPT Valve Function

1. Faults in EGRC-BPT system may set Code 36 or DTC P0402. To test overall function of system, go to next step. To test EGRC-BPT valve, see EGR BACKPRESSURE TRANSDUCER (EGR-BPT) & EGR CANISTER BACKPRESSURE TRANSDUCER (EGRC-BPT) VALVES (above).
2. Disconnect vacuum hose to fuel pressure regulator (on intake manifold). Disconnect vacuum hose to EGR and canister control solenoid at EGRC-BPT valve. Connect fuel pressure regulator manifold vacuum hose to EGRC-BPT valve, with a 0.04" (1 mm) restrictor installed in vacuum hose, to apply intake manifold vacuum directly to EGRC-BPT valve.
3. Start engine. Check for EGR valve lifting with engine speed less than 1500 RPM under no load. EGR valve should remain closed. Check for EGR valve lifting with engine speed at 2000-4000 RPM under no load. EGR valve should open, then close without sticking when engine is returned to idle.

EGR Valve

Using a hand-held vacuum pump, apply vacuum to EGR valve diaphragm. Replace EGR valve if pintle does not open.

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.

RADIATOR COOLING FANS

The ECM controls radiator cooling fan(s) based on vehicle speed, engine coolant temperature and A/C switch position. The following tables list correct cooling fan operation based on certain conditions. See appropriate A/C SWITCH ON or A/C SWITCH OFF table. If cooling fan does not operate as specified, see appropriate RADIATOR (COOLING) FAN CONTROL TEST.

A/C SWITCH ON

A/C SWITCH OFF