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

CLOSED THROTTLE POSITION SWITCH TEST

Check continuity between specified wire terminals of switch connector. See CLOSED THROTTLE POSITION SWITCH TEST table. There should be continuity with throttle valve fully closed, and no continuity with throttle valve off idle position. If continuity is not as specified, adjust switch. See SPECIFICATIONS article in the ENGINE PERFORMANCE section. If switch is adjusted properly, replace switch.

INHIBITOR SWITCH SYSTEM TEST

1. Ensure inhibitor switch functions properly. See INHIBITOR SWITCH TEST. 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 inhibitor relay. Relay is located in relay box next to battery. Place shift lever in Neutral or Park. Turn ignition on. Measure voltage between inhibitor relay connector terminal No. 1 and ground. For terminal identification (Scheme 40) Battery voltage should be present. If battery voltage is present, go to step 5). If battery voltage is not present, go to next step.
3. Turn ignition off. Disconnect and inspect inhibitor switch 8-pin harness connector for pushed-out, bent, damaged or corroded terminals. Repair connector as necessary. Connector is located on side of transaxle. Turn ignition on. Measure voltage between inhibitor switch 8-pin harness connector terminal No. 3 and ground. For terminal identification (Scheme 40) Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, check harness and connectors for open. Also check 10-amp fuse. Repair as necessary.
4. Turn ignition off. Check continuity between inhibitor relay connector No. 1 and inhibitor switch 8-pin harness connector terminal No. 6. Check continuity between inhibitor relay connector No. 1 and inhibitor switch 8-pin harness connector terminal No. 4. For terminal identification (Scheme 40) Continuity should exist in both checks. If continuity does not exist, check harness and connectors for open. Repair as necessary. If continuity exists, check inhibitor switch. See INHIBITOR SWITCH TEST.
5. Turn ignition off. On vehicles equipped with cruise control, check continuity between inhibitor relay connector No. 2 and ground. Check continuity between inhibitor relay connector No. 7 and ground. On vehicles without cruise control, check continuity between inhibitor relay connector No. 2 and ground. Check continuity between inhibitor relay connector No. 5 and ground. For terminal identification (Scheme 40) Continuity should exist in all checks. If continuity does not exist in any check, repair open in harness or connectors. If continuity exists in all checks, go to next step.
6. On vehicles equipped with cruise control, check continuity between ECM harness connector terminal No. 35 (Green/Orange wire) and inhibitor relay connector No. 6. On vehicles without cruise control, check continuity between ECM harness connector terminal No. 35 (Green/Orange wire) and inhibitor relay connector No. 3. For terminal identification (Scheme 40) Continuity should exist in all checks. If continuity does not exist in any check, repair open in harness or connectors. If continuity exists in all checks, check inhibitor relay. See «RELAYS»(ref-17477-S28305195042000122900000) under RELAYS & SOLENOIDS.

Scheme 40

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. (Scheme 41) If switch does not function as indicated, replace switch.

INHIBITOR SWITCH CONTINUITY

Scheme 41

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. Turn ignition off. Disconnect and inspect Neutral position switch 4-pin harness connector for pushed-out, bent, damaged or corroded terminals. Connector is located on top of transaxle. Repair connector as necessary. Check continuity between Black wire of Neutral position switch 4-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 4-pin harness connector. Continuity should exist. If continuity exists, check Neutral position switch. See NEUTRAL POSITION SWITCH TEST. If continuity does not exist, check harness and connectors for open. Repair as necessary.

NEUTRAL POSITION SWITCH TEST

Disconnect Neutral position switch 4-pin harness connector located on top of transaxle. Check continuity between Green/Orange wire and Black wire of Neutral position switch 4-pin connector. 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 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»(ref-17477-S40828913082000122900000). 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 pushed-out, 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. See POWER STEERING PRESSURE SWITCH TEST. 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

Valve Timing Control (VTC) Solenoid Test

VTC solenoids are located on rear corner of each cylinder head. To test solenoid, apply battery voltage across solenoid terminals. Replace solenoid if it does not operate.

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 relay box next to battery. Turn ignition on. Measure voltage between ground and fuel pump relay harness connector terminals No. 1 (Blue/Black wire) and No. 3 (Blue/Black wire). (Scheme 42) Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, check 15-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 Black wire. Check continuity between fuel pump relay harness connector terminal No. 5 (Black/Red wire) and fuel pump harness connector Black/Red 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 under center of instrument panel (connector is on passenger's side). Check continuity between ECM harness connector terminal No. 104 (Black/Yellow wire) and fuel pump relay harness connector No. 2 (Black/Yellow wire). see scheme 1and (Scheme 42). Continuity should exist. If continuity exists, check fuel pump relay. See «RELAYS»(ref-17477-S28305195042000122900000) under RELAYS & SOLENOIDS. If relay is okay, check fuel pump. See FUEL PUMP TEST. If continuity does not exist, check harness between ECM and relay. Repair harness and connectors as necessary.

Scheme 42

Fuel Pump Test

To test fuel pump, disconnect fuel pump connector, under rear seat. At fuel pump connector, check resistance between wire terminals specified in FUEL PUMP RESISTANCE TEST table. If resistance is not as specified, replace fuel pump.

FUEL PUMP RESISTANCE TEST

Fuel Injector System Test

1. With engine running, measure voltage between ground and ECM harness connector terminals No. 101 (Brown wire), No. 103 (Brown/Yellow wire), No. 110 (Brown/White wire), and No. 112 (Brown wire). ECM is located under center of instrument panel. see scheme 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. Measure voltage between ground and each injector harness connector White wire. Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, check 75-amp fusible link and 10-amp fuse located in engine compartment fuse box. If 75-amp fusible link and 10-amp fuse are okay, repair or replace harness or connectors.
3. Ensure ignition is off. Disconnect ECM harness connector. Measure voltage between ground and ECM harness connector terminal No. 109 (White wire). Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, check 25-amp fuse, located in fuse box in engine compartment. If 25-amp fuse is okay, repair or replace harness or connectors.
4. Check continuity between ECM harness connector terminals No. 101 (Brown wire), No. 103 (Brown/Yellow wire), No. 110 (Brown/White wire), and No. 112 (Brown wire) and corresponding injector harness connector wire color. Continuity should exist. If continuity exists, check injector. See FUEL INJECTOR TEST. 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

AIR REGULATOR TEST

Remove air regulator from engine. Check airflow through air regulator while immersed in cold or hot water. Air should flow freely at 68°F (20°C). Almost no air should flow at 176°F (80°C). If air regulator does not operate as described, replace unit.

AUXILIARY AIR CONTROL (AAC) VALVE SYSTEM TEST

1. Start engine and bring to operating temperature. Check idle speed. See «SPECIFICATIONS»(ref-17439) article in the ENGINE PERFORMANCE section. Adjust idle speed if necessary. See «ADJUSTMENTS»(ref-17440) article in the ENGINE PERFORMANCE section.
2. Check for stored codes. See RETRIEVING CODES in «TESTS W/CODES»(ref-17456) article in the ENGINE PERFORMANCE section. 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 Yellow wire. Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, check 10-amp fuse 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 Sky Blue wire. Continuity should exist. If continuity exists, check AAC valve. See AUXILIARY AIR CONTROL (AAC) VALVE TEST. 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.

AUXILIARY AIR CONTROL (AAC) VALVE TEST

To test AAC valve, check resistance across AAC valve connector terminals. If resistance is not approximately 10 ohms, replace AAC valve. Ensure plunger does not stick and plunger spring is not broken.

FAST IDLE CONTROL DEVICE (FICD) TEST

Note. Diagnostic procedures for Fast Idle Control Device (FICD) systems on Altima are not available from manufacturer.

Start Signal System Test

1. Locate ECM harness connector. ECM is located under center of instrument panel (connector is on passenger's side). Measure voltage between ground and ECM harness connector terminal No. 34 (Green/Black wire). see scheme 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 (Green/Black wire) and ignition switch harness connector terminal No. 6 (Black/Yellow wire). (Scheme 43) 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.

Scheme 43

EGR System Test

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. See EGR VALVE. Check EGR backpressure transducer. See EGR BACKPRESSURE TRANSDUCER (EGR-BPT). Replace malfunctioning components.
3. Measure voltage between ground and ECM harness connector terminal No. 105 (Light Green wire). see scheme 1 ECM is located under center of instrument panel (connector is on passenger's side) on Altima. 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 EGR-BPT on Altima. Turn ignition on. Measure voltage between ground and EGR and canister control solenoid harness connector Green/Yellow 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 fuse box under left instrument panel on Altima. Replace fuse if necessary. If fuse is okay, repair open in Green/Yellow 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. See EGR CONTROL SOLENOID. 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.

Pulsed Secondary Air Injection (PAIR) Valve Test

Apply vacuum to PAIR valve diaphragm. (Scheme 44) 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.

Scheme 44

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. (Scheme 45) 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.

Scheme 45

Radiator (Cooling) Fan Control Test (With A/C)

1. Start engine and warm to operating temperature. Set temperature lever to full cold. Turn A/C switch on. Turn fan switch on. Run engine at idle with A/C on for several minutes. Ensure radiator fan operates at low speed. If radiator fan does not operate at low speed, go to RADIATOR (COOLING) FAN LOW SPEED CONTROL TEST. If radiator fan operates at low speed, go to next step.
2. Turn A/C and fan switches off. Turn ignition off. Disconnect 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, see RADIATOR (COOLING) FAN HIGH SPEED CONTROL TEST. If radiator fan operates at high speed, system is functioning properly.

Radiator (Cooling) Fan Control Test (Without A/C)

1. Start engine and warm to operating temperature. Ensure radiator fan operates at low speed. If radiator fan does not operate at low speed, go to RADIATOR (COOLING) FAN LOW SPEED CONTROL TEST. If radiator fan operates at low speed, go to next step.
2. Turn ignition off. Disconnect 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, see RADIATOR (COOLING) FAN HIGH SPEED CONTROL TEST. 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. 1. (Scheme 46)- (Scheme 48). Turn ignition on. Measure voltage between ground and radiator fan relay No. 1 harness connector terminals No. 1 (White/Blue wire) and No. 3 (Green/Yellow wire). (Scheme 46)- (Scheme 48). 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. Check 10-amp fuse located in fuse box under left instrument panel. Replace fuse as necessary. Check 30-amp and 75-amp fusible links located in fusible link and fuse box left of battery. Replace fusible link(s) as necessary. If fuse and fusible links are okay, repair open in harness or connectors.
3. Turn ignition off. Disconnect radiator fan motor No. 1 and radiator fan motor No. 2 harness connectors. Check continuity between radiator fan motor No. 1 harness connector terminal "a" (White/Black wire) and radiator fan relay No. 1 harness connector terminal No. 5 (White/Black wire). Check continuity between radiator fan motor No. 2 harness connector terminal "e" (White/Black wire) and radiator fan relay No. 1 harness connector terminal No. 5 (White/Black wire). (Scheme 46)- (Scheme 48).
4. Check continuity between radiator fan motor No. 1 harness connector terminal "d" (Black wire) and ground. Check continuity between radiator fan motor No. 2 harness connector terminal "h" (Black wire) and ground. (Scheme 46)- (Scheme 48). 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 in appropriate wire or connector.
5. Disconnect ECM harness connector. ECM is located under center of instrument panel (connector is on passenger's side). Check continuity between ECM harness connector terminal No. 9 (Light Green/Red wire) and radiator fan relay No. 1 harness connector terminal No. 2 (Light Green/Red wire). see scheme 1and (Scheme 46) - (Scheme 48). Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair open in Light Green/Red wire or connectors between ECM and relay.
6. Check radiator fan relay No. 1. See «RELAYS»(ref-17477-S28305195042000122900000) under RELAYS & SOLENOIDS. Replace relay as necessary. If relay is okay, check fan motors. See RADIATOR FAN MOTOR TEST. Replace motor as necessary. If fan motor is okay, check ECM and ECM harness connector for damage, corrosion or improper connection. Repair as necessary.

Scheme 46

Scheme 47

Scheme 48

Radiator (Cooling) Fan High Speed Control Test

1. Turn ignition off. Disconnect radiator fan relay No. 2 and No. 3. (Scheme 49) Turn ignition on. Measure voltage between ground and radiator fan relay No. 2 and No. 3 harness connector terminals No. 1 (Green/Yellow wire) and No. 3 (White/Green wire). (Scheme 49)- (Scheme 51). 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. Check 10-amp fuse located in fuse box under left instrument panel. Replace fuse as necessary. Check 30-amp and 75-amp fusible links located in fusible link and fuse box left of battery. Replace fusible link(s) as necessary. If fuse and fusible links are okay, repair open in harness or connectors.
3. Turn ignition off. Disconnect radiator fan motor No. 1 and radiator fan motor No. 2 harness connectors. Check continuity between radiator fan motor No. 1 harness connector terminal "b" (White/Yellow wire) and radiator fan relay No. 2 harness connector terminal No. 5 (White/Yellow wire). Check continuity between radiator fan motor No. 2 harness connector terminal "f" (White/Blue wire) and radiator fan relay No. 3 harness connector terminal No. 5 (White/Blue wire). (Scheme 49)- (Scheme 51).
4. Check continuity between radiator fan motor No. 1 harness connector terminal "c" (White/Green wire) and radiator fan relay No. 2 harness connector No. 6 (White/Green wire). Check continuity between radiator fan motor No. 2 harness connector terminal "g" (White/Red wire) and radiator fan relay No. 2 harness connector No. 6 (White/Red wire). Check continuity between radiator fan relay No. 2 and No. 3 harness connector terminal No. 7 (Black wire) and ground. (Scheme 49)- (Scheme 51). 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 in appropriate wire or connector.
5. Disconnect ECM harness connector. ECM is located under center of instrument panel (connector is on passenger's side). Check continuity between ECM harness connector terminal No. 10 (Light Green wire) and radiator fan relays No. 2 and No. 3 harness connector terminal No. 2 (Light Green wire). see scheme 1and (Scheme 49) -19. Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair open in Light Green wire or connectors between ECM and relays.
6. Check radiator fan relays No. 2 and No. 3. See «RELAYS»(ref-17477-S28305195042000122900000) under RELAYS & SOLENOIDS. Replace relay(s) as necessary. If relays are okay, check fan motor(s). See RADIATOR FAN MOTOR TEST. Replace motor(s) as necessary. If fan motors are okay, check ECM and ECM harness connector for damage, corrosion or improper connection. Repair as necessary.

Scheme 49

Scheme 50

Scheme 51

Radiator Fan Motor Test

Disconnect fan motor harness connector(s). Apply battery across fan motor terminals and observe motor operation. see scheme 2 See FAN MOTOR OPERATION TEST table. If motor does not operate as indicated, replace motor.

FAN MOTOR OPERATION TEST

Scheme 52

Wiring Diagram (2.4L - 1 Of 2). Scheme 53

Wiring Diagram (2.4L - 2 Of 2). Scheme 54

See also:
• PIN VOLTAGE CHARTS