U1001 INFINITI QX56 2004 Factory Service Manual

EC-1
ENGINE CONTROL SYSTEM
B ENGINE
CONTENTS
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SECTION EC
A
EC
Revision: August 20072004 QX56 INDEX FOR DTC ........................................................ 8
Alphabetical Index .................................................... 8
DTC No. Index ....................................................... 12
PRECAUTIONS ........................................................ 16
Precautions for Supplemental Restraint System
(SRS) “AIR BAG” and “SEAT BELT PRE-TEN-
SIONER” ................................................................ 16
On Board Diagnostic (OBD) System of Engine and
A/T .......................................................................... 16
Precaution .............................................................. 16
Wiring Diagrams and Trouble Diagnosis ................ 19
PREPARATION ......................................................... 20
Special Service Tools ............................................. 20
Commercial Service Tools ...................................... 22
ENGINE CONTROL SYSTEM .................................. 23
System Diagram ..................................................... 23
Vacuum Hose Drawing ........................................... 24
System Chart ......................................................... 25
Multiport Fuel Injection (MFI) System .................... 26
Electronic Ignition (EI) System ............................... 28
Nissan Torque Demand (NTD) Control System ..... 29
Air Conditioning Cut Control ................................... 30
Fuel Cut Control (at No Load and High Engine
Speed) .................................................................... 30
CAN communication .............................................. 31
BASIC SERVICE PROCEDURE .............................. 32
Idle Speed and Ignition Timing Check .................... 32
Idle Speed/Ignition Timing/Idle Mixture Ratio
Adjustment ............................................................. 33
Accelerator Pedal Released Position Learning ...... 44
Throttle Valve Closed Position Learning ................ 44
Idle Air Volume Learning ........................................ 44
Fuel Pressure Check .............................................. 46
ON BOARD DIAGNOSTIC (OBD) SYSTEM ............ 49
Introduction ............................................................ 49
Two Trip Detection Logic ........................................ 49
Emission-related Diagnostic Information ................ 50
IVIS (Infiniti Vehicle Immobilizer System — NATS) ... 63
Malfunction Indicator Lamp (MIL) ........................... 63
OBD System Operation Chart ................................ 66TROUBLE DIAGNOSIS ............................................ 71
Trouble Diagnosis Introduction ............................... 71
DTC Inspection Priority Chart ................................. 76
Fail-safe Chart ........................................................ 77
Basic Inspection ..................................................... 79
Symptom Matrix Chart ............................................ 84
Engine Control Component Parts Location ............ 88
Circuit Diagram ....................................................... 94
ECM Harness Connector Terminal Layout ............. 96
ECM Terminals and Reference Value ..................... 96
CONSULT-II Function ...........................................103
Generic Scan Tool (GST) Function .......................116
CONSULT-II Reference Value in Data Monitor .....118
Major Sensor Reference Graph in Data Monitor
Mode .....................................................................121
TROUBLE DIAGNOSIS - SPECIFICATION VALUE .123
Description ............................................................123
Testing Condition ..................................................123
Inspection Procedure ............................................123
Diagnostic Procedure ...........................................124
TROUBLE DIAGNOSIS FOR INTERMITTENT INCI-
DENT .......................................................................127
Description ............................................................127
Diagnostic Procedure ...........................................127
POWER SUPPLY AND GROUND CIRCUIT ...........128
Wiring Diagram .....................................................128
Diagnostic Procedure ...........................................129
Ground Inspection ................................................133
DTC U1000, U1001 CAN COMMUNICATION LINE .135
Description ............................................................135
On Board Diagnosis Logic ....................................135
DTC Confirmation Procedure ...............................135
Wiring Diagram .....................................................136
Diagnostic Procedure ...........................................137
DTC P0037, P0038, P0057, P0058 HO2S2 HEATER .138
Description ............................................................138
CONSULT-II Reference Value in Data Monitor Mode
.138
On Board Diagnosis Logic ....................................138
DTC Confirmation Procedure ...............................139

EC-8Revision: August 2007
INDEX FOR DTC
2004 QX56
INDEX FOR DTCPFP:00024
Alphabetical IndexUBS00GZ3
NOTE:
If DTC U1000 or U1001 is displayed with other DTC, first perform the trouble diagnosis for DTC U1000,
U1001. Refer to EC-135, "
DTC U1000, U1001 CAN COMMUNICATION LINE" .
×:Applicable —: Not applicable
Items
(CONSULT-II screen terms)DTC*
1
TripMIL lighting
upReference page
CONSULT-II
GST*
2ECM*3
A/F SEN1 (B1) P1271 1271 2×EC-429
A/F SEN1 (B1) P1272 1272 2×EC-437
A/F SEN1 (B1) P1273 1273 2×EC-445
A/F SEN1 (B1) P1274 1274 2×EC-454
A/F SEN1 (B1) P1276 1276 2×EC-463
A/F SEN1 (B1) P1278 1278 2×EC-472
A/F SEN1 (B1) P1279 1279 2×EC-484
A/F SEN1 (B2) P1281 1281 2×EC-429
A/F SEN1 (B2) P1282 1282 2×EC-437
A/F SEN1 (B2) P1283 1283 2×EC-445
A/F SEN1 (B2) P1284 1284 2×EC-454
A/F SEN1 (B2) P1286 1286 2×EC-463
A/F SEN1 (B2) P1288 1288 2×EC-472
A/F SEN1 (B2) P1289 1289 2×EC-484
A/F SEN1 HTR (B1) P1031 1031 2×EC-354
A/F SEN1 HTR (B1) P1032 1032 2×EC-354
A/F SEN1 HTR (B2) P1051 1051 2×EC-354
A/F SEN1 HTR (B2) P1052 1052 2×EC-354
ACC COMMAND VALUE*7P1568 1568 1 —EC-524
A/T INTERLOCK P1730 1730 1×AT-139
A/T TCC S/V FNCTN P0744 0744 2×AT-121
APP SEN 1/CIRC P2122 2122 1×EC-556
APP SEN 1/CIRC P2123 2123 1×EC-556
APP SEN 2/CIRC P2127 2127 1×EC-562
APP SEN 2/CIRC P2128 2128 1×EC-562
APP SENSOR P2138 2138 1×EC-576
ASCD BRAKE SW P1572 1572 1 —EC-525, EC-534
ASCD SW P1564 1564 1 —EC-510, EC-517
ASCD VHL SPD SEN*6P1574 1574 1 —EC-542, EC-544
ATF TEMP SEN/CIRC P0710 0710 2×AT-131
BRAKE SW/CIRCUIT P1805 1805 2 —EC-551
CAN COMM CIRCUIT U1000
1000*41×EC-135
CAN COMM CIRCUIT U1001
1001*42—EC-135
CKP SEN/CIRCUIT P0335 0335 2×EC-255
CLOSED LOOP-B1 P1148 1148 1×EC-407
CLOSED LOOP-B2 P1168 1168 1×EC-407

EC-12Revision: August 2007
INDEX FOR DTC
2004 QX56
DTC No. IndexUBS00GZ4
NOTE:
If DTC U1000 or U1001 is displayed with other DTC, first perform the trouble diagnosis for DTC U1000,
U1001. Refer to EC-135, "
DTC U1000, U1001 CAN COMMUNICATION LINE" .
×:Applicable —: Not applicable
DTC*
1
Items
(CONSULT-II screen terms)TripMIL lighting
upReference page
CONSULT-II
GST*
2ECM*3
U1000
1000*4CAN COMM CIRCUIT 1×EC-135
U1001
1001*4CAN COMM CIRCUIT 2 —EC-135
P0000 0000NO DTC IS DETECTED.
FURTHER TESTING
MAY BE REQUIRED.———
P0037 0037 HO2S2 HTR (B1) 2×EC-138
P0038 0038 HO2S2 HTR (B1) 2×EC-138
P0057 0057 HO2S2 HTR (B2) 2×EC-138
P0058 0058 HO2S2 HTR (B2) 2×EC-138
P0101 0101 MAF SEN/CIRCUIT 1×EC-146
P0102 0102 MAF SEN/CIRCUIT 1×EC-154
P0103 0103 MAF SEN/CIRCUIT 1×EC-154
P 0 11 2 0 11 2 I AT S E N /C I R C U I T 2×EC-161
P 0 11 3 0 11 3 I AT S E N /C I R C U I T 2×EC-161
P0117 0117 ECT SEN/CIRCUIT 1×EC-165
P0118 0118 ECT SEN/CIRCUIT 1×EC-165
P0122 0122 TP SEN 2/CIRC 1×EC-171
P0123 0123 TP SEN 2/CIRC 1×EC-171
P0125 0125 ECT SENSOR 1×EC-178
P0127 0127 IAT SENSOR 2×EC-181
P0128 0128 THERMSTAT FNCTN 2×EC-184
P0138 0138 HO2S2 (B1) 2×EC-186
P0139 0139 HO2S2 (B1) 2×EC-196
P0158 0158 HO2S2 (B2) 2×EC-186
P0159 0159 HO2S2 (B2) 2×EC-196
P0171 0171 FUEL SYS-LEAN-B1 2×EC-208
P0172 0172 FUEL SYS-RICH-B1 2×EC-217
P0174 0174 FUEL SYS-LEAN-B2 2×EC-208
P0175 0175 FUEL SYS-RICH-B2 2×EC-217
P0181 0181 FTT SENSOR 2×EC-225
P0182 0182 FTT SEN/CIRCUIT 2×EC-231
P0183 0183 FTT SEN/CIRCUIT 2×EC-231
P0222 0222 TP SEN 1/CIRC 1×EC-236
P0223 0223 TP SEN 1/CIRC 1×EC-236
P0300 0300 MULTI CYL MISFIRE 2×EC-243
P0301 0301 CYL 1 MISFIRE 2×EC-243
P0302 0302 CYL 2 MISFIRE 2×EC-243
P0303 0303 CYL 3 MISFIRE 2×EC-243

EC-50Revision: August 2007
ON BOARD DIAGNOSTIC (OBD) SYSTEM
2004 QX56
The fail-safe function also operates when above diagnoses except MIL circuit are detected, and demands the
driver to repair the malfunction.
Emission-related Diagnostic InformationUBS00GZS
EMISSION-RELATED DIAGNOSTIC INFORMATION ITEMS
×: Applicable —: Not applicable Engine operating condition in fail-safe mode Engine speed will not rise more than 2,500 rpm due to the fuel cut
Items
(CONSULT-II screen terms)DTC*
1
SRT codeTest value/
Test limit
(GST only)1st trip DTCReference
page CONSULT-II
GST*
2ECM*3
CAN COMM CIRCUIT U1000
1000*5———EC-135
CAN COMM CIRCUIT U1001
1001*5——×EC-135
NO DTC IS DETECTED.
FURTHER TESTING
MAY BE REQUIRED.P0000 0000————
HO2S2 HTR (B1) P0037 0037×××EC-138
HO2S2 HTR (B1) P0038 0038×××EC-138
HO2S2 HTR (B2) P0057 0057×××EC-138
HO2S2 HTR (B2) P0058 0058×××EC-138
MAF SEN/CIRCUIT P0101 0101 — — —EC-146
MAF SEN/CIRCUIT P0102 0102 — — —EC-154
MAF SEN/CIRCUIT P0103 0103 — — —EC-154
IAT SEN/CIRCUIT P0112 0112 — —×EC-161
IAT SEN/CIRCUIT P0113 0113 — —×EC-161
ECT SEN/CIRCUIT P0117 0117 — — —EC-165
ECT SEN/CIRCUIT P0118 0118 — — —EC-165
TP SEN 2/CIRC P0122 0122 — — —EC-171
TP SEN 2/CIRC P0123 0123 — — —EC-171
ECT SENSOR P0125 0125 — — —EC-178
IAT SENSOR P0127 0127 — —×EC-181
THERMSTAT FNCTN P0128 0128 — —×EC-184
HO2S2 (B1) P0138 0138 —××EC-186
HO2S2 (B1) P0139 0139×××EC-196
HO2S2 (B2) P0158 0158 —××EC-186
HO2S2 (B2) P0159 0159×××EC-196
FUEL SYS-LEAN-B1 P0171 0171 — —×EC-208
FUEL SYS-RICH-B1 P0172 0172 — —×EC-217
FUEL SYS-LEAN-B2 P0174 0174 — —×EC-208
FUEL SYS-RICH-B2 P0175 0175 — —×EC-217
FTT SENSOR P0181 0181 — —×EC-225
FTT SEN/CIRCUIT P0182 0182 — —×EC-231
FTT SEN/CIRCUIT P0183 0183 — —×EC-231
TP SEN 1/CIRC P0222 0222 — — —EC-236
TP SEN 1/CIRC P0223 0223 — — —EC-236
MULTI CYL MISFIRE P0300 0300 — —×EC-243
CYL 1 MISFIRE P0301 0301 — —×EC-243
CYL 2 MISFIRE P0302 0302 — —×EC-243

EC-76Revision: August 2007
TROUBLE DIAGNOSIS
2004 QX56
DTC Inspection Priority ChartUBS00GZX
If some DTCs are displayed at the same time, perform inspections one by one based on the following priority
chart.
NOTE:
If DTC U1000 and/or U1001 is displayed with other DTC, first perform the trouble diagnosis for DTC
U1000, U1001. Refer to EC-135, "
DTC U1000, U1001 CAN COMMUNICATION LINE" .
Priority Detected items (DTC)
1

U1000 U1001 CAN communication line

P0101 P0102 P0103 Mass air flow sensor

P0112 P0113 P0127 Intake air temperature sensor

P0117 P0118 P0125 Engine coolant temperature sensor

P0122 P0123 P0222 P0223 P1225 P1226 P2135 Throttle position sensor

P0128 Thermostat function

P0181 P0182 P0183 Fuel tank temperature sensor

P0327 P0328 P0332 P0333 Knock sensor

P0335 Crankshaft position sensor (POS)

P0340 Camshaft position sensor (PHASE)

P0460 P0461 P0462 P0463 Fuel level sensor

P0500 Vehicle speed sensor

P0605 ECM

P0705 Park/Neutral position (PNP) switch

P1229 Sensor power supply

P1610 - P1615 NATS

P1706 Park/Neutral position (PNP) switch

P2122 P2123 P2127 P2128 P2138 Accelerator pedal position sensor

DTC U1000, U1001 CAN COMMUNICATION LINE
EC-135
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EC
Revision: August 20072004 QX56
DTC U1000, U1001 CAN COMMUNICATION LINEPFP:23710
DescriptionUBS00H0I
CAN (Controller Area Network) is a serial communication line for real time application. It is an on-vehicle mul-
tiplex communication line with high data communication speed and excellent error detection ability. Many elec-
tronic control units are equipped onto a vehicle, and each control unit shares information and links with other
control units during operation (not independent). In CAN communication, control units are connected with 2
communication lines (CAN H line, CAN L line) allowing a high rate of information transmission with less wiring.
Each control unit transmits/receives data but selectively reads required data only.
On Board Diagnosis LogicUBS00H0J
*1: This self-diagnosis has the one trip detection logic.
*2: The MIL will not light up for this diagnosis.
DTC Confirmation ProcedureUBS00H0K
1. Turn ignition switch ON and wait at least 3 seconds.
2. Select “DATA MONITOR” mode with CONSULT-II.
3. If 1st trip DTC is detected, go to EC-137, "
Diagnostic Procedure" .
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
U1000*
1
1000*1
CAN communication line

ECM cannot communicate to other control
units.

ECM cannot communicate for more than the
specified time.

Harness or connectors
(CAN communication line is open or
shorted) U1001*
2
1001*2

EC-136Revision: August 2007
DTC U1000, U1001 CAN COMMUNICATION LINE
2004 QX56
Wiring DiagramUBS00H0L
BBWA0873E

DTC U1000, U1001 CAN COMMUNICATION LINE
EC-137
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EC
Revision: August 20072004 QX56
Diagnostic ProcedureUBS00H0M
Go to LAN-3, "Precautions When Using CONSULT-II" .

EC-334Revision: August 2007
DTC P0460 FUEL LEVEL SENSOR
2004 QX56
DTC P0460 FUEL LEVEL SENSORPFP:25060
Component DescriptionUBS00H5X
The fuel level sensor is mounted in the fuel level sensor unit. The
sensor detects a fuel level in the fuel tank and transmits a signal to
the combination meter. The combination meter sends the fuel level
sensor signal to the ECM through CAN communication line.
It consists of two parts, one is mechanical float and the other is vari-
able resistor. Fuel level sensor output voltage changes depending on
the movement of the fuel mechanical float.
On Board Diagnosis LogicUBS00H5Y
NOTE:
If DTC P0460 is displayed with DTC U1000 or U1001, first perform the trouble diagnosis for DTC U1000,
U1001. Refer to EC-135, "
DTC U1000, U1001 CAN COMMUNICATION LINE" .
When the vehicle is parked, naturally the fuel level in the fuel tank is stable. It means that output signal of the
fuel level sensor does not change. If ECM senses sloshing signal from the sensor, fuel level sensor malfunc-
tion is detected.
DTC Confirmation ProcedureUBS00H5Z
NOTE:
If DTC Confirmation Procedure has been previously conducted, always turn ignition switch OFF and wait at
least 10 seconds before conducting the next test.
WITH CONSULT-II
1. Turn ignition switch ON.
2. Select “DATA MONITOR” mode with CONSULT-II.
3. Start engine and wait maximum of 2 consecutive minutes.
4. If 1st trip DTC is detected, go to EC-335, "
Diagnostic Procedure"
.
WITH GST
Follow the procedure “WITH CONSULT-II” above.
BBIA0402E
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0460
0460Fuel level sensor circuit
noiseEven though the vehicle is parked, a signal
being varied is sent from the fuel level sensor
to ECM.

Harness or connectors
(The CAN communication line is open or
shorted)

Harness or connectors
(The sensor circuit is open or shorted)

Combination meter

Fuel level sensor
SEF 1 95 Y

EC-336Revision: August 2007
DTC P0461 FUEL LEVEL SENSOR
2004 QX56
DTC P0461 FUEL LEVEL SENSORPFP:25060
Component DescriptionUBS00H62
The fuel level sensor is mounted in the fuel level sensor unit. The
sensor detects a fuel level in the fuel tank and transmits a signal to
the combination meter. The combination meter sends the fuel level
sensor signal to the ECM through CAN communication line.
It consists of two parts, one is mechanical float and the other is vari-
able resistor. Fuel level sensor output voltage changes depending on
the movement of the fuel mechanical float.
On Board Diagnosis LogicUBS00H63
NOTE:
If DTC P0461 is displayed with DTC U1000 or U1001, first perform the trouble diagnosis for DTC U1000,
U1001. Refer to EC-135, "
DTC U1000, U1001 CAN COMMUNICATION LINE" .
Driving long distances naturally affect fuel gauge level.
This diagnosis detects the fuel gauge malfunction of the gauge not moving even after a long distance has
been driven.
Overall Function CheckUBS00H64
Use this procedure to check the overall function of the fuel level sensor function. During this check, a 1st trip
DTC might not be confirmed.
WAR NIN G:
When performing following procedure, be sure to observe the handling of the fuel. Refer to FL-9,
"FUEL TANK" .
TESTING CONDITION:
Before starting overall function check, preparation of draining fuel and refilling fuel is required.
WITH CONSULT-II
NOTE:
Start from step 10, if it is possible to confirm that the fuel cannot be drained by 30 (7-7/8 US gal, 6-5/
8 Imp gal) in advance.
1. Prepare a fuel container and a spare hose.
2. Release fuel pressure from fuel line, refer to EC-46, "
FUEL PRESSURE RELEASE" .
3. Remove the fuel feed hose on the fuel level sensor unit.
4. Connect a spare fuel hose where the fuel feed hose was removed.
5. Turn ignition switch OFF and wait at least 10 seconds then turn ON.
6. Select “FUEL LEVEL SE” in “DATA MONITOR” mode with CONSULT-II.
BBIA0402E
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0461
0461Fuel level sensor circuit
range/performanceThe output signal of the fuel level sensor
does not change within the specified range
even though the vehicle has been driven a
long distance.

Harness or connectors
(The CAN communication line is open or
shorted)

Harness or connectors
(The sensor circuit is open or shorted)

Combination meter

Fuel level sensor