diagram INFINITI QX4 2001 Factory Repair Manual

SEF348N
IWhen measuring ECM signals with a circuit tester, never
allow the two tester probes to contact.
Accidental contact of probes will cause a short circuit and
damage the ECM power transistor.
IDo not use ECM ground terminals when measuring input/
output voltage. Doing so may result in damage to the
ECM's transistor. Use a ground other than the ECM
terminals, such as the ground.
SEF099WB
IRegarding model R50, ª-B1º indicates the right bank and
ª-B2º indicates the left bank as shown in the figure.
IBank 1 includes No. 1 cylinder.
Wiring Diagrams and Trouble DiagnosisNBEC0006When you read Wiring diagrams, refer to the following:
IGI-34, ªHOW TO READ WIRING DIAGRAMSº
IEL-9, ªPOWER SUPPLY ROUTINGº for power distribution circuit
When you perform trouble diagnosis, refer to the following:
IGI-38, ªHOW TO FOLLOW TEST GROUP IN TROUBLE DIAGNOSISº
IGI-34, ªHOW TO PERFORM EFFICIENT DIAGNOSIS FOR AN ELECTRICAL INCIDENTº
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PRECAUTIONS
Precautions (Cont'd)
EC-17

Circuit DiagramNBEC0010
MEC939C
ENGINE AND EMISSION CONTROL OVERALL SYSTEM
Circuit Diagram
EC-24

System DiagramNBEC0011
SEF930Y
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ENGINE AND EMISSION CONTROL OVERALL SYSTEM
System Diagram
EC-25

Vacuum Hose DrawingNBEC0012
SEF931Y
Refer to ªSystem Diagramº, EC-25 for Vacuum Control System.
ENGINE AND EMISSION CONTROL OVERALL SYSTEM
Vacuum Hose Drawing
EC-26

25 CHECK HEATED OXYGEN SENSOR 1 (FRONT) (BANK 1) SIGNAL
With CONSULT-II
1. Stop engine.
2. Replace heated oxygen sensor 1 (front) (bank 1).
3. Start engine and warm it up to normal operating temperature.
4. Run engine at approx. 2,000 rpm for approx. 2 minutes under no-load.
5. See ªHO2S1 MNTR (B1)º in ªDATA MONITORº mode.
6. Maintaining engine at 2,000 rpm under no-load (engine is warmed up to normal operating temperature.), check that the
monitor fluctuates between ªLEANº and ªRICHº more than 5 times during 10 seconds.
1 time: RICH®LEAN®RICH
2 times: RICH®LEAN®RICH®LEAN®RICH
Without CONSULT-II
1. Stop engine.
2. Replace heated oxygen sensor 1 (front) (bank 1).
3. Start engine and warm it up to normal operating temperature.
4. Run engine at approx. 2,000 rpm for approx. 2 minutes under no-load.
5. Set voltmeter probe between ECM terminal 63 and ground.
6. Make sure that the voltage fluctuates between 0 - 0.3V and 0.6 - 1.0V more than 5 times during 10 seconds at 2,000
rpm.
1 time: 0 - 0.3V®0.6 - 1.0V®0 - 0.3V
2 times: 0 - 0.3V®0.6 - 1.0V®0 - 0.3V®0.6 - 1.0V®0 - 0.3V
OK or NG
OK©INSPECTION END
NG©GO TO 26.
26 DETECT MALFUNCTIONING PART
Check the following.
ICheck fuel pressure regulator. Refer to EC-40.
ICheck mass air flow sensor and its circuit. Refer to EC-150.
ICheck injector and its circuit. Refer to EC-616.
Clean or replace if necessary.
ICheck engine coolant temperature sensor and its circuit. Refer to EC-187.
ICheck ECM function by substituting another known-good ECM.
(ECM may be the cause of a problem, but this is rarely the case.)
©GO TO 3.
27 CHECK HEATED OXYGEN SENSOR 1 (FRONT) (BANK 1) HARNESS
1. Turn off engine and disconnect battery ground cable.
2. Disconnect ECM harness connector.
3. Disconnect heated oxygen sensor 1 (front) (bank 1) harness connector.
4. Check harness continuity between ECM terminal 63 and heated oxygen sensor 1 (front) RH harness connector terminal
1.
Refer to Wiring Diagram, EC-196.
Continuity should exist.
OK or NG
OK©GO TO 30.
NG©GO TO 29.
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BASIC SERVICE PROCEDURE
Idle Speed/Ignition Timing/Idle Mixture Ratio Adjustment (Cont'd)
EC-53

28 CHECK HEATED OXYGEN SENSOR 1 (FRONT) (BANK 2) HARNESS
1. Turn off engine and disconnect battery ground cable.
2. Disconnect ECM harness connector.
3. Disconnect heated oxygen sensor 1 (front) (bank 2) harness connector.
4. Check harness continuity between ECM terminal 62 and front heated oxygen sensor LH harness connector terminal 1.
Refer to Wiring Diagram, EC-197.
Continuity should exist.
OK or NG
OK©GO TO 30.
NG©GO TO 29.
29 REPAIR OR REPLACE
Repair or replace harness between ECM and heated oxygen sensor 1 (front).
©GO TO 3.
30 PREPARATION FOR ªCOº % CHECK
With CONSULT-II
1. Reconnect ECM harness connector.
2. Turn ignition switch ªONº.
3. Select ªENG COOLANT TEMPº in ªACTIVE TESTº mode.
4. Set ªENG COOLANT TEMPº to 5ÉC (41ÉF) by touching ªDOWNº and ªQdº.
SEF172Y
Without CONSULT-II
1. Disconnect ECM harness connector.
2. Disconnect engine coolant temperature sensor harness connector.
3. Connect a resistor (4.4 kW) between terminals of engine coolant temperature sensor harness connector.
SEF982UA
©GO TO 31.
BASIC SERVICE PROCEDURE
Idle Speed/Ignition Timing/Idle Mixture Ratio Adjustment (Cont'd)
EC-54

Main Power Supply and Ground Circuit
WIRING DIAGRAMNBEC0047
MEC940C
TROUBLE DIAGNOSIS FOR POWER SUPPLY
Main Power Supply and Ground Circuit
EC-142

DIAGNOSTIC PROCEDURENBEC0049
1 INSPECTION START
Start engine.
Is engine running?
YesorNo
Ye s©GO TO 9.
No©GO TO 2.
2 CHECK ECM POWER SUPPLY CIRCUIT-I
1. Turn ignition switch ªOFFº and then ªONº.
2. Check voltage between ECM terminal 43 and ground with CONSULT-II or tester.
SEF291X
OK or NG
OK©GO TO 4.
NG©GO TO 3.
3 DETECT MALFUNCTIONING PART
Check the following.
I10A fuses
IHarness connectors M33, F22
IHarness for open or short between ECM and ignition switch
©Repair harness or connectors.
4 CHECK ECM GROUND CIRCUIT FOR OPEN AND SHORT-I
1. Turn ignition switch ªOFFº.
2. Disconnect ECM harness connector.
3. Check harness continuity between ECM terminals 48, 57, 106, 108 and engine ground.
Refer to WIRING DIAGRAM.
Continuity should exist.
4. Also check harness for short to ground and short to power.
OK or NG
OK©GO TO 5.
NG©Repair open circuit or short to ground or short to power in harness or connectors.
TROUBLE DIAGNOSIS FOR POWER SUPPLY
Main Power Supply and Ground Circuit (Cont'd)
EC-144

15 DETECT MALFUNCTIONING PART
Check the following.
IHarness connectors E1, M1
IHarness connectors M94, F27
I10A fuse
©Repair harness or connectors.
16 CHECK HARNESS CONTINUITY BETWEEN ECM RELAY AND ECM FOR OPEN AND SHORT
1. Check harness continuity between ECM terminals 110, 112 and ECM relay terminal 6.
Refer to WIRING DIAGRAM.
Continuity should exist.
2. Also check harness for short to ground and short to power.
OK or NG
OK©GO TO 18.
NG©GO TO 17.
17 DETECT MALFUNCTIONING PART
Check the following.
IHarness connectors E1, M1 and M32, F23
IHarness for open or short between ECM and ECM relay
©Repair open circuit or short to ground or short to power in harness or connectors.
18 CHECK ECM RELAY
1. Apply 12V direct current between ECM relay terminals 1 and 2.
2. Check continuity between relay terminals 3 and 5, 6 and 7.
SEF296X
OK or NG
OK©GO TO 19.
NG©Replace ECM relay.
19 CHECK ECM GROUND CIRCUIT FOR OPEN AND SHORT-II
1. Turn ignition switch ªOFFº.
2. Disconnect ECM harness connector.
3. Check harness continuity between ECM terminals 48, 57, 106, 108 and engine ground.
Refer to WIRING DIAGRAM.
Continuity should exist.
4. Also check harness for short to ground and short to power.
OK or NG
OK©GO TO 20.
NG©Repair open circuit or short to ground or short to power in harness or connectors.
TROUBLE DIAGNOSIS FOR POWER SUPPLY
Main Power Supply and Ground Circuit (Cont'd)
EC-148

Wiring DiagramNBEC0056
MEC942C
DTC P0100 MASS AIR FLOW SENSOR (MAFS)
Wiring Diagram
EC-154