Engine Controls - System/component Tests: Other Nissan Altima U13

ECM POWER & GROUND CIRCUITS

1. Turn ignition on. Measure voltage between ground and ECM harness connector terminals No. 38 (Orange wire) and No. 47 (Orange wire). see scheme 1 ECM is located under center of instrument panel (connector is on passenger's side). 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). see scheme 1 Continuity should exist. If continuity does not exist, repair harness or connectors. If continuity exists, check ECM pin terminals for damage or connection of ECM harness connector.
3. Turn ignition off. Disconnect ECM harness connector. Disconnect ECM relay. ECM relay is located next to ECM. Check continuity between ECM relay harness connector Orange wire (terminal No. 3) and ECM harness connector terminals No. 38 (Orange wire) and No. 47 (Orange wire). Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair harness or connectors.
4. Measure voltage between ground and ECM relay harness connector White wire (terminals No. 1 and 5). Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, check for open in harness or connectors. Check 25-amp fusible link. Check continuity between ECM relay harness connector White wire and battery.
5. Measure voltage between ground and ECM harness connector terminal No. 46 (White wire). Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, check for open in harness or connectors. Check 25-amp fusible link. Check continuity between ECM relay harness connector White wire 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 harness or connectors.
7. Check continuity between ECM harness connector terminal No. 4 (White/Green wire) and ECM relay harness connector White/Green wire (terminal No. 2). Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair harness or connectors.
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. See RELAYS under RELAYS & SOLENOIDS. 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. Check continuity of Red/Black wire between ECM harness connector and ignition switch.

Scheme 55

ENGINE SENSORS & SWITCHES

Note. For ECM connector terminal identification, see PIN VOLTAGE CHARTS article in the ENGINE PERFORMANCE section and WIRING DIAGRAMS at the end of this article.

MASS AIRFLOW SENSOR

Faults in mass airflow sensor circuit may set Code 12. To test system, see CODE 12 diagnostic procedures in TESTS W/CODES article in the ENGINE PERFORMANCE section.

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 Orange 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 (1)

A/C SWITCH

See PIN VOLTAGE CHARTS article in the ENGINE PERFORMANCE section.

CRANKSHAFT POSITION SENSOR

Faults in crankshaft position sensor circuit may set Code 11. To test system, see CODE 11 diagnostic procedures in TESTS W/CODES article in the ENGINE PERFORMANCE section.

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 (1)

KNOCK (DETONATION) SENSOR

Faults in detonation sensor circuit may set Code 34. To test system, see CODE 34 diagnostic procedures in TESTS W/CODES article in the ENGINE PERFORMANCE section.

To test sensor, disconnect sensor connector. See DETONATION SENSOR LOCATION table. 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 system, see CODE 13 diagnostic procedures in TESTS W/CODES article in the ENGINE PERFORMANCE section.

To test sensor, disconnect sensor connector. See ENGINE (COOLANT) TEMPERATURE SENSOR LOCATION table. 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 system, see CODE 33 (and/or CODE 53) diagnostic procedures in TESTS W/CODES article in the ENGINE PERFORMANCE section.

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 system, see CODE 35 diagnostic procedures in TESTS W/CODES article in the ENGINE PERFORMANCE section.

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.

FUEL TEMPERATURE SENSOR RESISTANCE (1)

THROTTLE POSITION SENSOR (TPS)

Faults in TPS circuit may set Code 43. To test system, see CODE 43 diagnostic procedures in TESTS W/CODES article in the ENGINE PERFORMANCE section.

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. See THROTTLE POSITION SENSOR RESISTANCE TEST table. If resistance value does not change smoothly, replace TPS.
2. If resistance is not as specified, check harness. If harness is okay, adjust TPS. See «ADJUSTMENTS»(ref-17440) article in the ENGINE PERFORMANCE section. If resistance is still not as specified after adjustment, replace TPS.

THROTTLE POSITION SENSOR RESISTANCE TEST

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/condenser (cooling) fan relay.
5. Mixture heater relay.
6. Neutral/inhibitor relay.

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

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.

Air Injection Valve Control Solenoid

See AIR INJECTION under EMISSION SYSTEMS & SUB-SYSTEMS .

EGR Control Solenoid

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

Fast Idle Control Device (FICD) Solenoid

See FAST IDLE CONTROL DEVICE (FICD) under IDLE CONTROL SYSTEM .

Power Valve Control Solenoid

See POWER VALVE under AIR INDUCTION SYSTEMS.

Pressure Regulator Vacuum Relief (PRVR) Control Solenoid

See FUEL DELIVERY under FUEL SYSTEM.

Swirl Control Valve Control Solenoid

See SWIRL CONTROL VALVE under AIR INDUCTION SYSTEMS.

FUEL DELIVERY

Note. For fuel system pressure testing, see FUEL PRESSURE under FUEL SYSTEM in BASIC TESTING article in the ENGINE PERFORMANCE section.

Start Signal

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 BASIC TESTING article in the ENGINE PERFORMANCE section. If pressure is not as specified, replace fuel pressure regulator.

Fuel Pump Relay

See RELAYS under RELAYS & SOLENOIDS.

If ECM receives incorrect start (cranking) signal, fuel control system may not operate properly. See START SIGNAL under IGNITION SYSTEM.

Feedback System

Ensure ignition timing and idle speed are adjusted. See ADJUSTMENTS article in the ENGINE PERFORMANCE section. Warm engine to operating temperature. Run engine unloaded at 2000 RPM for 2 minutes. Enter self-diagnostic Mode II. See TESTS W/CODES article in the ENGINE PERFORMANCE section. 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 in ADJUSTMENTS article in the ENGINE PERFORMANCE section.

If ECM receives incorrect start (cranking) signal, idle control system may not operate properly. See START SIGNAL under IGNITION SYSTEM.

Note. Altima uses a thermal-mechanical device. See AIR REGULATOR TEST.

IGNITION SYSTEMS

Note. For basic ignition checks, see BASIC TESTING article in the ENGINE PERFORMANCE section.

POWER TRANSISTOR

1. Disconnect power transistor connector. (Scheme 56) At power transistor connector, check continuity between the following terminals, noting ohmmeter test lead polarity: "a" (+) and "b" (-). "a" (+) and "c" (-).
2. If there is continuity, replace power transistor. If there is no continuity, reverse ohmmeter test lead polarity and check continuity across terminals listed in previous step. If there is no continuity, replace power transistor. If there is continuity, power transistor is okay.

Scheme 56

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 PIN VOLTAGE CHARTS article in the ENGINE PERFORMANCE section. Inputs that affect timing include the following

1. Crank angle sensor.
2. Airflow meter.
3. Engine (coolant) temperature sensor.
4. Idle switch.
5. Start (cranking) signal.
6. Battery voltage.

Detonation (Knock) Retard

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

Carbon Canister

Remove hoses from carbon canister. Blow air into canister ports as shown. (Scheme 57) 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 57

If ECM receives an incorrect start (cranking) signal, EGR control solenoid may not operate properly. See START SIGNAL under IGNITION SYSTEMS.

EGR Function

Faults in EGR function circuit may set Code 32. To test function, see CODE 32 diagnostic procedures in TESTS W/CODES article in the ENGINE PERFORMANCE section.

EGR Backpressure Transducer (EGR-BPT)

Plug one port of EGR backpressure transducer (EGR-BPT) and apply vacuum to other port. (Scheme 58)and (Scheme 59). 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.

Scheme 58

Scheme 59

EGR Valve

Using a hand-held vacuum pump, apply vacuum to EGR valve diaphragm. (Scheme 60) Replace EGR valve if pintle does not open.

Scheme 60

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.

1. Disconnect vacuum lines and electrical connector from solenoid. Remove solenoid. Using hand-held vacuum pump, apply vacuum to port "B" of solenoid. see scheme 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.

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