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EC-302Revision: November 2009
DTC P0172, P0175 FUEL INJECTION SYSTEM FUNCTION
2006 QX56
Specification data are reference values and are measured between each terminal and ground.
Pulse signal is measured by CONSULT-II.
CAUTION:
Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in dam-
age to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.
: Average voltage for pulse signal (Actual pulse signal can be confirmed by oscilloscope.)TER-
MINAL NO. WIRE
COLOR ITEM
CONDITION DATA (DC Voltage)
2 O/B A/F sensor 1 heater
(bank 1) [Engine is running]
Warm-up condition
Idle speed Approximately 5V
16 BR/R A/F sensor 1 (bank 1) [Engine is running]
Warm-up condition
Idle speed Approximately 3.1V
35 BR/G Approximately 2.6V
56 LG/B Approximately 2.3V
75 P/B Approximately 2.3V
21
22
23
44 O/L
BR
GR/W
O
Fuel injector No. 5
Fuel injector No. 3
Fuel injector No. 1
Fuel injector No. 7 [Engine is running]
Warm-up condition
Idle speed
NOTE:
The pulse cycle changes depending on rpm at
idle. BATTERY VOLTAGE
(11 - 14V)
[Engine is running]
Warm-up condition
Engine speed: 2,000 rpm BATTERY VOLTAGE
(11 - 14V)
PBIB1584E
PBIB0042E
PBIB0043E
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DTC P0172, P0175 FUEL INJECTION SYSTEM FUNCTIONEC-303
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BANK 2
BBWA2091E
Page 1515 of 3383

EC-304Revision: November 2009
DTC P0172, P0175 FUEL INJECTION SYSTEM FUNCTION
2006 QX56
Specification data are reference values and are measured between each terminal and ground.
Pulse signal is measured by CONSULT-II.
CAUTION:
Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in dam-
age to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.
: Average voltage for pulse signal (Actual pulse signal can be confirmed by oscilloscope.)TER-
MINAL NO. WIRE
COLOR ITEM
CONDITION DATA (DC Voltage)
40
41
42
63 Y/G
P
L
G Fuel injector No. 6
Fuel injector No. 4
Fuel injector No. 2
Fuel injector No. 8 [Engine is running]
Warm-up condition
Idle speed
NOTE:
The pulse cycle changes depending on rpm at
idle. BATTERY VOLTAGE
(11 - 14V)
[Engine is running]
Warm-up condition
Engine speed: 2,000 rpm BATTERY VOLTAGE
(11 - 14V)
24 BR/W A/F sensor 1 heater
(bank 2) [Engine is running]
Warm-up condition
Idle speed Approximately 5V
57 L/P A/F sensor 1 (bank 2) [Engine is running]
Warm-up condition
Idle speed Approximately 2.6V
58 GR/G Approximately 2.3V
76 G/L Approximately 3.1V
77 BR/B Approximately 2.3V
PBIB0042E
PBIB0043E
PBIB1584E
Page 1516 of 3383
DTC P0172, P0175 FUEL INJECTION SYSTEM FUNCTIONEC-305
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Revision: November 2009 2006 QX56
Diagnostic ProcedureUBS00L0S
1. CHECK EXHAUST GAS LEAK
1. Start engine and run it at idle.
2. Listen for an exhaust gas leak before three way catalyst (manifold).
OK or NG
OK >> GO TO 2.
NG >> Repair or replace.
2. CHECK FOR INTAKE AIR LEAK
Listen for an intake air leak after the mass air flow sensor.
OK or NG
OK >> GO TO 3.
NG >> Repair or replace.
PBIB1216E
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EC-306Revision: November 2009
DTC P0172, P0175 FUEL INJECTION SYSTEM FUNCTION
2006 QX56
3. CHECK A/F SENSOR 1 INPUT SIGNAL CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect corresponding A/F sensor 1 harness connector.
3. Disconnect ECM harness connector.
4. Check harness continuity between the following terminals. Refer to Wiring Diagram.
5. Check harness continuity between the following terminals and ground. Refer to Wiring Diagram.
6. Also check harness for short to power.
OK or NG
OK >> GO TO 4.
NG >> Repair open circuit or short to ground or short to power in harness or connectors.
A/F sensor 1 terminal ECM terminal
Bank 1 11
6
27 5
53 5
65 6
Bank 2 17
6
27 7
55 7
65 8
Continuity should exist.
Bank 1 Bank 2
A/F sensor 1 terminal ECM terminal A/F sensor 1 terminal ECM terminal 11 617 6
27 527 7
53 555 7
65 665 8
Continuity should not exist.
BBIA0376E
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DTC P0172, P0175 FUEL INJECTION SYSTEM FUNCTIONEC-307
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Revision: November 2009 2006 QX56
4. CHECK FUEL PRESSURE
1. Release fuel pressure to zero. Refer to EC-80, "
FUEL PRESSURE RELEASE" .
2. Install fuel pressure gauge and check fuel pressure. Refer to EC-82, "
FUEL PRESSURE CHECK" .
OK or NG
OK >> GO TO 6.
NG >> GO TO 5.
5. DETECT MALFUNCTIONING PART
Check the following.
Fuel pump and circuit (Refer to EC-604, "FUEL PUMP" .)
Fuel pressure regulator (Refer to EC-82, "FUEL PRESSURE CHECK" .)
>> Repair or replace.
6. CHECK MASS AIR FLOW SENSOR
With CONSULT-II
1. Install all removed parts.
2. Check “MASS AIR FLOW ” in “DATA MONITOR” mode with CONSULT-II.
With GST
1. Install all removed parts.
2. Check mass air flow sensor signal in Service $01 with GST.
OK or NG
OK >> GO TO 7.
NG >> Check connectors for rusted terminals or loose connections in the mass air flow sensor circuit or grounds. Refer to EC-171, "
DTC P0101 MAF SENSOR" .
At idling: Approximately 350 kPa (3.57 kg/cm
2 , 51 psi)
3.0 - 9.0 g·m/sec: at idling
9.0 - 28.0 g·m/sec: at 2,500 rpm
3.0 - 9.0 g·m/sec: at idling
9.0 - 28.0 g·m/sec: at 2,500 rpm
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EC-308Revision: November 2009
DTC P0172, P0175 FUEL INJECTION SYSTEM FUNCTION
2006 QX56
7. CHECK FUNCTION OF FUEL INJECTOR
With CONSULT-II
1. Start engine.
2. Perform “POWER BALANCE ” in “ACTIVE TEST” mode with
CONSULT-II.
3. Make sure that each circuit produces a momentary engine speed drop.
Without CONSULT-II
1. Start engine.
2. Listen to each fuel injector operating sound.
OK or NG
OK >> GO TO 8.
NG >> Perform trouble diagnosis for FUEL INJECTOR, refer to EC-598, "
FUEL INJECTOR" .
8. CHECK FUEL INJECTOR
1. Remove fuel injector assembly. Refer to EM-31, "
FUEL INJECTOR AND FUEL TUBE" .
Keep fuel hose and all fuel injectors connected to fuel injector gallery.
2. Confirm that the engine is cooled down and there are no fire hazards near the vehicle.
3. Disconnect all fuel injector harness connectors.
4. Disconnect all ignition coil harness connectors.
5. Prepare pans or saucers under each fuel injectors.
6. Crank engine for about 3 seconds. Make sure fuel does not drip from fuel injector.
OK or NG
OK (Does not drip.)>>GO TO 9.
NG (Drips.)>>Replace the fuel injectors from which fuel is dripping. Always replace O-ring with new one.
9. CHECK INTERMITTENT INCIDENT
Refer to EC-144, "
TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT" .
>> INSPECTION END
PBIB0133E
Clicking noise should be heard.
PBIB1986E
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DTC P0181 FTT SENSOREC-309
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Revision: November 2009 2006 QX56
DTC P0181 FTT SENSORPFP:22630
Component DescriptionUBS00H34
The fuel tank temperature sensor is used to detect the fuel tempera-
ture inside the fuel tank. The sensor modifies a voltage signal from
the ECM. The modified signal returns to the ECM as the fuel temper-
ature input. The sensor uses a thermistor which is sensitive to the
change in temperature. The electrical resistance of the thermistor
decreases as temperature increases.
*: This data is reference value and is measured between ECM terminal 107 (Fuel
tank temperature sensor) and ground.
CAUTION:
Do 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 ECM terminals, such as the ground.
On Board Diagnosis LogicUBS00H35
DTC Confirmation ProcedureUBS00H36
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. Wait at least 10 seconds. If the result is NG, go to EC-312, "
Diagnostic Procedure" .
If the result is OK, go to following step.
4. Check “COOLAN TEMP/S ” value.
If “COOLAN TEMP/S ” is less than 60°C (140 °F), the result will
be OK.
If “COOLAN TEMP/S ” is above 60°C (140°F), go to the following
step.
5. Cool engine down until “COOLAN TEMP/S” is less than 60° C
(140 °F).
6. Wait at least 10 seconds.
7. If 1st trip DTC is detected, go to EC-312, "
Diagnostic Procedure" .
BBIA0583E
Fluid temperature
°C (°F) Voltage*
V Resistance
kΩ
20 (68) 3.52.3 - 2.7
50 (122) 2.20.79 - 0.90
SEF012P
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0181
0181 Fuel tank temperature
sensor circuit range/
performance Rationally incorrect voltage from the sensor is
sent to ECM, compared with the voltage sig-
nals from engine coolant temperature sensor
and intake air temperature sensor.
Harness or connectors
(The sensor circuit is open or shorted)
Fuel tank temperature sensor
SEF174Y