2005 INFINITI QX4 low oil pressure

DTC P0745 LINE PRESSURE SOLENOID VALVE
AT-119
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Revision: October 20052005 QX56
DTC P0745 LINE PRESSURE SOLENOID VALVEPFP:31940
DescriptionECS00CFZ
The line pressure solenoid valve regulates the oil pump discharge pressure to suit the driving condition in
response to a signal sent from the TCM.
The line pressure duty cycle value is not consistent when the closed throttle position signal is “ON”.
To confirm the line pressure duty cycle at low pressure, the accelerator (throttle) should be open until
the closed throttle position signal is “OFF”.
CONSULT-II Reference ValueECS00CG0
On Board Diagnosis LogicECS00CG1

This is an OBD-II self-diagnostic item.

Diagnostic trouble code “P0745 L/PRESS SOL/CIRC” with CONSULT-II is detected under the following
conditions.
–When TCM detects an improper voltage drop when it tries to operate the solenoid valve.
–When TCM detects as irregular by comparing target value with monitor value.
Possible CauseECS00CG2

Harness or connectors
(The solenoid circuit is open or shorted.)

Line pressure solenoid valve
DTC Confirmation ProcedureECS00CG3
NOTE:
If “DTC Confirmation Procedure” has been previously performed, always turn ignition switch “OFF”
and wait at least 10 seconds before performing the next test.
After the repair, perform the following procedure to confirm the malfunction is eliminated.
WITH CONSULT-II
1. Turn ignition switch “ON” and select “DATA MONITOR” mode for
“ENGINE” with CONSULT-II.
2. Engine start and wait at least 5 second.
3. If DTC is detected, go to AT-120, "
Diagnostic Procedure" .
WITH GST
Follow the procedure “With CONSULT-II”.
Item name Condition Display value (Approx.)
LINE PRES SOL During driving 0.2 - 0.6 A
BCIA0030E

AT-188
TROUBLE DIAGNOSIS FOR SYMPTOMS
Revision: October 20052005 QX56
5. DETECT MALFUNCTIONING ITEM
1. Disassemble A/T. Refer to AT-262, "
Disassembly" .
2. Check the following items:
–Reverse brake. Refer to AT-262, "Disassembly" .
OK or NG
OK >> GO TO 9.
NG >> Repair or replace damaged parts.
6. CHECK LINE PRESSURE
Check the line pressure with the engine idling. Refer to AT- 5 1 , "
LINE
PRESSURE TEST" .
OK or NG
OK >> GO TO 9.
NG - 1 >> Line pressure high. GO TO 7.
NG - 2 >> Line pressure low. GO TO 8.
7. DETECT MALFUNCTIONING ITEM
1. Check control valve with TCM. Refer to AT- 2 3 1 , "
Control Valve With TCM and A/T Fluid Temperature Sen-
sor 2" .
2. Disassemble A/T. Refer to AT-262, "
Disassembly" .
3. Check the following items:
–Oil pump assembly. Refer to AT-280, "Oil Pump" .
OK or NG
OK >> GO TO 9.
NG >> Repair or replace damaged parts.
8. DETECT MALFUNCTIONING ITEM
1. Check control valve with TCM. Refer to AT- 2 3 1 , "
Control Valve With TCM and A/T Fluid Temperature Sen-
sor 2" .
2. Disassemble A/T. Refer to AT-262, "
Disassembly" .
3. Check the following items:
–Oil pump assembly. Refer to AT-280, "Oil Pump" .
–Power train system. Refer to AT-262, "Disassembly" .
–Transmission case. Refer to AT-262, "Disassembly" .
OK or NG
OK >> GO TO 9.
NG >> Repair or replace damaged parts.
SAT4 9 4G

TROUBLE DIAGNOSIS FOR SYMPTOMS
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Revision: October 20052005 QX56
5. CHECK LINE PRESSURE
Check line pressure at idle with selector lever in “D” position. Refer
to AT-51, "
LINE PRESSURE TEST" .
OK or NG
OK >> GO TO 8.
NG - 1 >> Line pressure high. GO TO 6.
NG - 2 >> Line pressure low. GO TO 7.
6. DETECT MALFUNCTIONING ITEM
1. Check control valve with TCM. Refer to AT-231, "
Control Valve With TCM and A/T Fluid Temperature Sen-
sor 2" .
2. Disassemble A/T. Refer to AT- 2 6 2 , "
Disassembly" .
3. Check the following items:
–Oil pump assembly. Refer to AT-280, "Oil Pump" .
OK or NG
OK >> GO TO 8.
NG >> Repair or replace damaged parts.
7. DETECT MALFUNCTIONING ITEM
1. Check control valve with TCM. Refer to AT-231, "
Control Valve With TCM and A/T Fluid Temperature Sen-
sor 2" .
2. Disassemble A/T. Refer to AT- 2 6 2 , "
Disassembly" .
3. Check the following items:
–Oil pump assembly. Refer to AT-280, "Oil Pump" .
–Power train system. Refer to AT- 2 6 2 , "Disassembly" .
–Transmission case. Refer to AT - 2 6 2 , "Disassembly" .
OK or NG
OK >> GO TO 8.
NG >> Repair or replace damaged parts.
8. CHECK A/T FLUID CONDITION
1. Remove oil pan. Refer to AT-231, "
Control Valve With TCM and A/T Fluid Temperature Sensor 2" .
2. Check A/T fluid condition. Refer to AT- 5 0 , "
Fluid Condition
Check" .
OK or NG
OK >> GO TO 9.
NG >> GO TO 12.
SAT4 9 4G
SCIA5199E

TROUBLE DIAGNOSIS FOR SYMPTOMS
AT-193
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Revision: October 20052005 QX56
3. CHECK ACCELERATOR PEDAL POSITION (APP) SENSOR
Check accelerator pedal position (APP) sensor. Refer to AT-123, "
DTC P1705 THROTTLE POSITION SEN-
SOR"
OK or NG
OK >> GO TO 4.
NG >> Repair or replace accelerator pedal position (APP) sensor.
4. CHECK A/T FLUID LEVEL
Check A/T fluid level. Refer to AT- 1 3 , "
Checking A/T Fluid" .
OK or NG
OK >> GO TO 5.
NG >> Refill ATF.
5. CHECK LINE PRESSURE
Check line pressure at the engine stall point. Refer to AT-51, "
LINE
PRESSURE TEST" .
OK or NG
OK >> GO TO 8.
NG - 1 >> Line pressure high. GO TO 6.
NG - 2 >> Line pressure low. GO TO 7.
6. DETECT MALFUNCTIONING ITEM
1. Check control valve with TCM. Refer to AT-231, "
Control Valve With TCM and A/T Fluid Temperature Sen-
sor 2" .
2. Disassemble A/T. Refer to AT- 2 6 2 , "
Disassembly" .
3. Check the following items:
–Oil pump assembly. Refer to AT-280, "Oil Pump" .
OK or NG
OK >> GO TO 8.
NG >> Repair or replace damaged parts.
SAT6 3 8A
SAT4 9 4G

AT-198
TROUBLE DIAGNOSIS FOR SYMPTOMS
Revision: October 20052005 QX56
4. CHECK LINE PRESSURE
Check line pressure at the engine stall point. Refer to AT- 5 1 , "
LINE
PRESSURE TEST" .
OK or NG
OK >> GO TO 7.
NG - 1 >> Line pressure high. GO TO 5.
NG - 2 >> Line pressure low. GO TO 6.
5. DETECT MALFUNCTIONING ITEM
1. Check control valve with TCM. Refer to AT- 2 3 1 , "
Control Valve With TCM and A/T Fluid Temperature Sen-
sor 2" .
2. Disassemble A/T. Refer to AT-262, "
Disassembly" .
3. Check the following items:
–Oil pump assembly. Refer to AT-280, "Oil Pump" .
OK or NG
OK >> GO TO 7.
NG >> Repair or replace damaged parts.
6. DETECT MALFUNCTIONING ITEM
1. Check control valve with TCM. Refer to AT- 2 3 1 , "
Control Valve With TCM and A/T Fluid Temperature Sen-
sor 2" .
2. Disassemble A/T. Refer to AT-262, "
Disassembly" .
3. Check the following items:
–Oil pump assembly. Refer to AT-280, "Oil Pump" .
–Power train system. Refer to AT-262, "Disassembly" .
–Transmission case. Refer to AT-262, "Disassembly" .
OK or NG
OK >> GO TO 7.
NG >> Repair or replace damaged parts.
7. CHECK A/T FLUID CONDITION
1. Remove oil pan. Refer to AT-231, "
Control Valve With TCM and A/T Fluid Temperature Sensor 2" .
2. Check A/T fluid condition. Refer to AT- 5 0 , "
Fluid Condition
Check" .
OK or NG
OK >> GO TO 8.
NG >> GO TO 11.
SAT4 9 4G
SCIA5199E

AT-200
TROUBLE DIAGNOSIS FOR SYMPTOMS
Revision: October 20052005 QX56
P1705 THROTTLE POSITION SENSOR" , AT-108, "DTC P0720 VEHICLE SPEED SENSOR A/T
(REVOLUTION SENSOR)" , AT-133, "DTC P1721 VEHICLE SPEED SENSOR MTR" .
NO >> GO TO 3.
3. CHECK A/T FLUID LEVEL
Check A/T fluid level. Refer to AT-13, "
Checking A/T Fluid" .
OK or NG
OK >> GO TO 4.
NG >> Refill ATF.
4. CHECK LINE PRESSURE
Check line pressure at the engine stall point. Refer to AT- 5 1 , "
LINE
PRESSURE TEST" .
OK or NG
OK >> GO TO 7.
NG - 1 >> Line pressure high. GO TO 5.
NG - 2 >> Line pressure low. GO TO 6.
5. DETECT MALFUNCTIONING ITEM
1. Check control valve with TCM. Refer to AT- 2 3 1 , "
Control Valve With TCM and A/T Fluid Temperature Sen-
sor 2" .
2. Disassemble A/T. Refer to AT-262, "
Disassembly" .
3. Check the following items:
–Oil pump assembly. Refer to AT-280, "Oil Pump" .
OK or NG
OK >> GO TO 7.
NG >> Repair or replace damaged parts.
6. DETECT MALFUNCTIONING ITEM
1. Check control valve with TCM. Refer to AT- 2 3 1 , "
Control Valve With TCM and A/T Fluid Temperature Sen-
sor 2" .
2. Disassemble A/T. Refer to AT-262, "
Disassembly" .
3. Check the following items:
–Oil pump assembly. Refer to AT-280, "Oil Pump" .
–Power train system. Refer to AT-262, "Disassembly" .
–Transmission case. Refer to AT-262, "Disassembly" .
OK or NG
OK >> GO TO 7.
NG >> Repair or replace damaged parts.
SAT6 3 8A
SAT4 9 4G

TROUBLE DIAGNOSIS FOR SYMPTOMS
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Revision: October 20052005 QX56
3. CHECK LINE PRESSURE
Check line pressure at the engine stall point. Refer to AT-51, "
LINE
PRESSURE TEST" .
OK or NG
OK >> GO TO 6.
NG - 1 >> Line pressure high. GO TO 4.
NG - 2 >> Line pressure low. GO TO 5.
4. DETECT MALFUNCTIONING ITEM
1. Check control valve with TCM. Refer to AT-231, "
Control Valve With TCM and A/T Fluid Temperature Sen-
sor 2" .
2. Disassemble A/T. Refer to AT- 2 6 2 , "
Disassembly" .
3. Check the following items:
–Oil pump assembly. Refer to AT-280, "Oil Pump" .
OK or NG
OK >> GO TO 7.
NG >> Repair or replace damaged parts.
5. DETECT MALFUNCTIONING ITEM
1. Check control valve with TCM. Refer to AT-231, "
Control Valve With TCM and A/T Fluid Temperature Sen-
sor 2" .
2. Disassemble A/T. Refer to AT- 2 6 2 , "
Disassembly" .
3. Check the following items:
–Oil pump assembly. Refer to AT-280, "Oil Pump" .
–Power train system. Refer to AT- 2 6 2 , "Disassembly" .
–Transmission case. Refer to AT - 2 6 2 , "Disassembly" .
OK or NG
OK >> GO TO 7.
NG >> Repair or replace damaged parts.
6. CHECK A/T FLUID CONDITION
1. Remove oil pan. Refer to AT-231, "
Control Valve With TCM and A/T Fluid Temperature Sensor 2" .
2. Check A/T fluid condition. Refer to AT- 5 0 , "
Fluid Condition
Check" .
OK or NG
OK >> GO TO 7.
NG >> GO TO 10.
SAT4 9 4G
SCIA5199E

ATC-18
REFRIGERATION SYSTEM
Revision: October 20052005 QX56
REFRIGERATION SYSTEMPFP:KA990
Refrigerant CycleEJS003X1
REFRIGERANT FLOW
The refrigerant flows in the standard pattern, that is, through the compressor, the condenser with liquid tank,
through the front and rear evaporators, and back to the compressor. The refrigerant evaporation through the
evaporator coils are controlled by front and rear externally equalized expansion valves, located inside the front
and rear evaporator cases.
Refrigerant System ProtectionEJS003X2
REFRIGERANT PRESSURE SENSOR
The refrigerant system is protected against excessively high or low pressures by the refrigerant pressure sen-
sor, located on the condenser. If the system pressure rises above or falls below the specifications, the refriger-
ant pressure sensor detects the pressure inside the refrigerant line and sends a voltage signal to the ECM.
The ECM de-energizes the A/C relay to disengage the magnetic compressor clutch when pressure on the high
pressure side detected by refrigerant pressure sensor is over about 2,746 kPa (28 kg/cm
2 , 398 psi), or below
about 120 kPa (1.22 kg/cm
2 , 17.4 psi).