INFINITI QX4 2005 Factory Service Manual

AT-40
ON BOARD DIAGNOSTIC (OBD) SYSTEM
Revision: October 20052005 QX56
Malfunction Indicator Lamp (MIL)ECS00CE8
DESCRIPTION
The MIL is located on the instrument panel.
1. The MIL will light up when the ignition switch is turned “ON” with-
out the engine running. This is a bulb check.

If the MIL does not light up, refer to DI-30, "WARNING LAMPS" .
2. When the engine is started, the MIL should go off.
If the MIL remains on, the on board diagnostic system has
detected an engine system malfunction.
SEF 2 17 U

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DTC Inspection Priority ChartECS00CE9
If some DTCs are displayed at the same time, perform inspections one by one based on the following priority
chart.
NOTE:
If DTC U1000 is displayed with other DTCs, first perform the trouble diagnosis for DTC U1000. Refer to
AT-9 5
.
Fail-SafeECS00CEA
The TCM has an electrical fail-safe mode. This mode makes it possible to operate even if there is an error in a
main electronic control input/output signal circuit. In fail-safe mode the transmission is fixed in 2nd, 4th or 5th
(depending on the breakdown position), so the customer should feel “slipping” or “poor acceleration”.
Even when the electronic circuits are normal, under special conditions (for example, when slamming on the
brake with the wheels spinning drastically and stopping the tire rotation), the transmission can go into fail-safe
mode. If this happens, switch “OFF” the ignition switch for 10 seconds, then switch it “ON” again to return to
the normal shift pattern. Therefore, the customer's vehicle has returned to normal, so handle according to the
“diagnostics flow” (Refer to AT-44, "
WORK FLOW" ).
FAI L-S AFE FUN CT ION
If any malfunction occurs in a sensor or solenoid, this function controls the A/T to mark driving possible.
Vehicle Speed Sensor

Signals are input from two systems - from vehicle speed sensor A/T (revolution sensor) installed on the
transmission and from combination meter so normal driving is possible even if there is a malfunction in
one of the systems. And if vehicle speed sensor A/T (revolution sensor) has unusual cases, 5th gear is
prohibited.
Accelerator Pedal Position Sensor

If there is a malfunction in one of the systems, the accelerator opening angle is controlled by ECM accord-
ing to a pre-determined accelerator angle to make driving possible. And if there are malfunctions in tow
systems, the engine speed is fixed by ECM to a pre-determined engine speed to make driving possible.
Throttle Position Sensor

If there is a malfunction in one of the systems, the accelerator opening angle is controlled by ECM accord-
ing to a pre-determined accelerator angle to make driving possible. And if there are malfunctions in tow
systems, the accelerator opening angle is controlled by the idle signal sent from the ECM which is based
on input indicating either idle condition or off-idle condition (pre-determined accelerator opening) in order
to make driving possible.
PNP Switch

In the unlikely event that a malfunction signal enters the TCM, the position indicator is switched “OFF”, the
starter relay is switched “OFF” (starter starting is disabled), the back-up lamp relay switched “OFF” (back-
up lamp is OFF) and the position is fixed to the “D” range to make driving possible.
Starter Relay

The starter relay is switched “OFF”. (Starter starting is disabled.)
Priority Detected items (DTC)
1 U1000 CAN communication line
2 Except above

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Revision: October 20052005 QX56
A/T Interlock

If there is an A/T interlock judgment malfunction, the transmission is fixed in 2nd gear to make driving pos-
sible.
NOTE:
When the vehicle is driven fixed in 2nd gear, a turbine revolution sensor malfunction is displayed,
but this is not a turbine revolution sensor malfunction.

When the coupling pattern below is detected, the fail-safe action corresponding to the pattern is per-
formed.
A/T INTERLOCK COUPLING PATTERN TABLE

: NG X: OK
A/T 1st Engine Braking

When there is an A/T first gear engine brake judgment malfunction, the low coast brake solenoid is
switched “OFF” to avoid the engine brake operation.
Line Pressure Solenoid

The solenoid is switched “OFF” and the line pressure is set to the maximum hydraulic pressure to make
driving possible.
Torque Converter Clutch Solenoid

The solenoid is switched “OFF” to release the lock-up.
Low Coast Brake Solenoid

When a (electrical or functional) malfunction occurs, in order to make driving possible, the engine brake is
not applied in 1st and 2nd gear.
Input Clutch Solenoid

If a (electrical or functional) malfunction occurs with the solenoid either “ON” or “OFF”, the transmission is
held in 4th gear to make driving possible.
Direct Clutch Solenoid

If a (electrical or functional) malfunction occurs with the solenoid either “ON” or “OFF”, the transmission is
held in 4th gear to make driving possible.
Front Brake Solenoid

If a (electrical or functional) malfunction occurs with the solenoid “ON”, in order to make driving possible,
the A/T is held in 5th gear; if the solenoid is OFF, 4th gear.
High and Low Reverse Clutch Solenoid

If a (electrical or functional) malfunction occurs with the solenoid either “ON” or “OFF”, the transmission is
held in 4th gear to make driving possible.
Turbine Revolution Sensor 1 or 2

The control is the same as if there were no turbine revolution sensors, 5th gear is prohibited.
Gear positionATF pressure switch output
Fail-safe
functionClutch pressure output pattern after fail-safe func-
tion
SW3
(I/C)SW6
(HLR/
C)SW5
(D/C)SW1
(FR/B)SW2
(LC/B)I/C HLR/C D/C FR/B LC/B L/U
A/T inter-
lock cou-
pling pattern3rd – X X –
Held in
2nd gearOFF OFF ON OFF OFF OFF
4th – X X –
Held in
2nd gearOFF OFF ON OFF OFF OFF
5th X X – X
Held in
2nd gearOFF OFF ON OFF OFF OFF

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How To Perform Trouble Diagnosis For Quick and Accurate RepairECS00CEB
INTRODUCTION
The TCM receives a signal from the vehicle speed sensor, accelerator pedal position sensor (throttle position
sensor) or PNP switch and provides shift control or lock-up control via A/T solenoid valves.
The TCM also communicates with the ECM by means of a signal
sent from sensing elements used with the OBD-related parts of the
A/T system for malfunction-diagnostic purposes. The TCM is capa-
ble of diagnosing malfunctioning parts while the ECM can store mal-
functions in its memory.
Input and output signals must always be correct and stable in the
operation of the A/T system. The A/T system must be in good oper-
ating condition and be free of valve seizure, solenoid valve malfunc-
tion, etc.
It is much more difficult to diagnose a error that occurs intermittently
rather than continuously. Most intermittent errors are caused by poor
electric connections or improper wiring. In this case, careful check-
ing of suspected circuits may help prevent the replacement of good
parts.
A visual check only may not find the cause of the errors. A road test
with CONSULT-II (or GST) or a circuit tester connected should be
performed. Follow the AT-44, "
WORK FLOW" .
Before undertaking actual checks, take a few minutes to talk with a
customer who approaches with a driveability complaint. The cus-
tomer can supply good information about such errors, especially
intermittent ones. Find out what symptoms are present and under
what conditions they occur. A “Diagnostic Worksheet” as shown on
the example (Refer to AT- 4 5
) should be used.
Start your diagnosis by looking for “conventional” errors first. This will
help troubleshoot driveability errors on an electronically controlled
engine vehicle.
Also check related Service bulletins.
SAT6 3 1IB
SAT6 3 2I
SEF 2 34 G

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Revision: October 20052005 QX56
WORK FLOW
A good understanding of the malfunction conditions can make troubleshooting faster and more accurate.
In general, each customer feels differently about a malfunction. It is important to fully understand the symp-
toms or conditions for a customer complaint.
Make good use of the two sheets provided, “Information From Customer” (Refer to AT- 4 5
) and “Diagnostic
Worksheet” (Refer to AT- 4 5
), to perform the best troubleshooting possible.
Work Flow Chart
*1.AT-4 5*2.AT- 4 5*3.AT- 4 1
*4.AT-5 0*5.AT- 5 0, AT - 5 1*6.AT- 5 3
*7.AT-8 3*8.AT- 3 7*9.AT- 9 5
*10.AT-174*11.AT- 1 7 7*12.AT- 2 1 9
*13.AT-6 0*14.AT- 3 8*15.AT- 1 6 6
*16.EC-49
WCIA0251E

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DIAGNOSTIC WORKSHEET
Information From Customer
KEY POINTS

WHAT..... Vehicle & A/T model

WHEN..... Date, Frequencies

WHERE..... Road conditions

HOW..... Operating conditions, Symptoms
Diagnostic Worksheet Chart
Customer name MR/MS Model & Year VIN
Trans. Model Engine Mileage
Malfunction Date Manuf. Date In Service Date
Frequency❏ Continuous❏ Intermittent ( times a day)
Symptoms❏ Vehicle does not move. (❏ Any position❏ Particular position)
❏ No up-shift (❏ 1st → 2nd❏ 2nd → 3rd❏ 3rd → 4th ❏ 4th → 5th)
❏ No down-shift (❏ 5th → 4th ❏ 4th → 3rd❏ 3rd → 2nd❏ 2nd → 1st)
❏ Lock-up malfunction
❏ Shift point too high or too low.
❏ Shift shock or slip (❏ N → D❏ Lock-up❏ Any drive position)
❏ Noise or vibration
❏ No kick down
❏ No pattern select
❏ Others
()
Malfunction indicator lamp (MIL)❏ Continuously lit❏ Not lit
1❏ Read the item on cautions concerning fail-safe and understand the customer's complaint.AT- 4 1
2❏ ATF inspection
AT- 5 0❏ Leak (Repair leak location.)
❏ Sta te
❏ Amount
3❏ Stall test and line pressure test
AT- 5 0
, AT-
51
❏ Stall test
❏ Torque converter one-way clutch
❏ Front brake
❏ High and low reverse clutch
❏ Low coast brake
❏ Forward brake
❏ Reverse brake
❏ Forward one-way clutch❏ 1st one-way clutch
❏ 3rd one-way clutch
❏ Engine
❏ Line pressure low
❏ Except for input clutch and direct
clutch, clutches and brakes OK
❏ Line pressure inspection - Suspected part:

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4❏ Perform all road tests and enter checks in required inspection items.AT-5 3
4-1.Check before engine is started
AT-5 4
❏ AT-180, "A/T CHECK Indicator Lamp Does Not Come On" .
❏ Perform self-diagnostics Enter checks for detected items. AT- 8 5
❏ AT- 9 5 , "DTC U1000 CAN COMMUNICATION LINE"
❏ AT- 9 9 , "DTC P0615 START SIGNAL CIRCUIT"
❏ AT- 1 0 3 , "DTC P0700 TCM"
❏ AT- 1 0 4 , "DTC P0705 PARK/NEUTRAL POSITION SWITCH"
❏ AT- 1 0 8 , "DTC P0720 VEHICLE SPEED SENSOR A/T (REVOLUTION SENSOR)"
❏ AT- 11 3 , "DTC P0725 ENGINE SPEED SIGNAL"
❏ AT- 11 5 , "DTC P0740 TORQUE CONVERTER CLUTCH SOLENOID VALVE"
❏ AT- 11 7 , "DTC P0744 A/T TCC S/V FUNCTION (LOCK-UP)"
❏ AT- 11 9 , "DTC P0745 LINE PRESSURE SOLENOID VALVE"
❏ AT- 1 2 1 , "DTC P1702 TRANSMISSION CONTROL MODULE (RAM)"
❏ AT- 1 2 2 , "DTC P1703 TRANSMISSION CONTROL MODULE (ROM)"
❏ AT- 1 2 3 , "DTC P1705 THROTTLE POSITION SENSOR"
❏ AT- 1 2 6 , "DTC P1710 A/T FLUID TEMPERATURE SENSOR CIRCUIT"
❏ AT- 1 3 1 , "DTC P1716 TURBINE REVOLUTION SENSOR"
❏ AT- 1 3 3 , "DTC P1721 VEHICLE SPEED SENSOR MTR"
❏ AT- 1 3 5 , "DTC P1730 A/T INTERLOCK"
❏ AT- 1 3 8 , "DTC P1731 A/T 1ST ENGINE BRAKING"
❏ AT- 1 4 0 , "DTC P1752 INPUT CLUTCH SOLENOID VALVE"
❏ AT- 1 4 2 , "DTC P1754 INPUT CLUTCH SOLENOID VALVE FUNCTION"
❏ AT- 1 4 4 , "DTC P1757 FRONT BRAKE SOLENOID VALVE"
❏ AT- 1 4 6 , "DTC P1759 FRONT BRAKE SOLENOID VALVE FUNCTION"
❏ AT- 1 4 8 , "DTC P1762 DIRECT CLUTCH SOLENOID VALVE"
❏ AT- 1 5 0 , "DTC P1764 DIRECT CLUTCH SOLENOID VALVE FUNCTION"
❏ AT- 1 5 2 , "DTC P1767 HIGH AND LOW REVERSE CLUTCH SOLENOID VALVE"
❏ AT- 1 5 4 , "DTC P1769 HIGH AND LOW REVERSE CLUTCH SOLENOID VALVE
FUNCTION"
❏ AT- 1 5 6 , "DTC P1772 LOW COAST BRAKE SOLENOID VALVE"
❏ AT- 1 5 8 , "DTC P1774 LOW COAST BRAKE SOLENOID VALVE FUNCTION"
❏ AT- 1 6 0 , "DTC P1841 ATF PRESSURE SWITCH 1"
❏ AT- 1 6 2 , "DTC P1843 ATF PRESSURE SWITCH 3"
❏ AT- 1 6 4 , "DTC P1845 ATF PRESSURE SWITCH 5"
❏ AT- 1 6 6 , "DTC P1846 ATF PRESSURE SWITCH 6"
4-2.Idle inspection
AT-5 4
❏ AT-180, "Engine Cannot Be Started In “P” or “N” Position"
❏ AT-181, "In “P” Position, Vehicle Moves When Pushed"
❏ AT-182, "In “N” Position, Vehicle Moves"
❏ AT-183, "Large Shock (“N” to “D” Position)"
❏ AT-187, "Vehicle Does Not Creep Backward In “R” Position"
❏ AT-190, "Vehicle Does Not Creep Forward In “D” Position"
4-3.Driving tests
AT-5 5
Part 1
❏ AT-192, "
Vehicle Cannot Be Started From D1"
❏ AT-195, "A/T Does Not Shift: D1 → D2"
❏ AT-197, "A/T Does Not Shift: D2 → D3"
❏ AT-199, "A/T Does Not Shift: D3 → D4"
❏ AT-202, "A/T Does Not Shift: D4 → D5"
❏ AT-204, "A/T Does Not Perform Lock-up"
❏ AT-206, "A/T Does Not Hold Lock-up Condition"
❏ AT-208, "Lock-up Is Not Released"
❏ AT-209, "Engine Speed Does Not Return to Idle"

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44-3Part 2
AT- 5 7
❏ AT-192, "Vehicle Cannot Be Started From D1"
❏ AT-195, "A/T Does Not Shift: D1 → D2"
❏ AT-197, "A/T Does Not Shift: D2 → D3"
❏ AT-199, "A/T Does Not Shift: D3 → D4"
Part 3
AT- 5 8
❏ AT-210, "A/T Does Not Shift: 5th gear → 4th gear"
❏ AT-213, "A/T Does Not Shift: 4th gear → 3rd gear"
❏ AT-214, "A/T Does Not Shift: 3rd gear → 2nd gear"
❏ AT-216, "A/T Does Not Shift: 2nd gear → 1st gear"
❏ AT-219, "Vehicle Does Not Decelerate By Engine Brake"
❏ Perform self-diagnostics Enter checks for detected items. AT- 8 5
❏ AT-95, "DTC U1000 CAN COMMUNICATION LINE"
❏ AT-99, "DTC P0615 START SIGNAL CIRCUIT"
❏ AT-103, "DTC P0700 TCM"
❏ AT-104, "DTC P0705 PARK/NEUTRAL POSITION SWITCH"
❏ AT-108, "DTC P0720 VEHICLE SPEED SENSOR A/T (REVOLUTION SENSOR)"
❏ AT-113, "DTC P0725 ENGINE SPEED SIGNAL"
❏ AT-115, "DTC P0740 TORQUE CONVERTER CLUTCH SOLENOID VALVE"
❏ AT-117, "DTC P0744 A/T TCC S/V FUNCTION (LOCK-UP)"
❏ AT-119, "DTC P0745 LINE PRESSURE SOLENOID VALVE"
❏ AT-121, "DTC P1702 TRANSMISSION CONTROL MODULE (RAM)"
❏ AT-122, "DTC P1703 TRANSMISSION CONTROL MODULE (ROM)"
❏ AT-123, "DTC P1705 THROTTLE POSITION SENSOR"
❏ AT-126, "DTC P1710 A/T FLUID TEMPERATURE SENSOR CIRCUIT"
❏ AT-131, "DTC P1716 TURBINE REVOLUTION SENSOR"
❏ AT-133, "DTC P1721 VEHICLE SPEED SENSOR MTR"
❏ AT-135, "DTC P1730 A/T INTERLOCK"
❏ AT-138, "DTC P1731 A/T 1ST ENGINE BRAKING"
❏ AT-140, "DTC P1752 INPUT CLUTCH SOLENOID VALVE"
❏ AT-142, "DTC P1754 INPUT CLUTCH SOLENOID VALVE FUNCTION"
❏ AT-144, "DTC P1757 FRONT BRAKE SOLENOID VALVE"
❏ AT-146, "DTC P1759 FRONT BRAKE SOLENOID VALVE FUNCTION"
❏ AT-148, "DTC P1762 DIRECT CLUTCH SOLENOID VALVE"
❏ AT-150, "DTC P1764 DIRECT CLUTCH SOLENOID VALVE FUNCTION"
❏ AT-152, "DTC P1767 HIGH AND LOW REVERSE CLUTCH SOLENOID VALVE"
❏ AT-154, "DTC P1769 HIGH AND LOW REVERSE CLUTCH SOLENOID VALVE
FUNCTION"
❏ AT-156, "DTC P1772 LOW COAST BRAKE SOLENOID VALVE"
❏ AT-158, "DTC P1774 LOW COAST BRAKE SOLENOID VALVE FUNCTION"
❏ AT-160, "DTC P1841 ATF PRESSURE SWITCH 1"
❏ AT-162, "DTC P1843 ATF PRESSURE SWITCH 3"
❏ AT-164, "DTC P1845 ATF PRESSURE SWITCH 5"
❏ AT-166, "DTC P1846 ATF PRESSURE SWITCH 6"
5❏ Inspect each system for items found to be NG in the self-diagnostics and repair or replace the malfunction
parts.
6❏ Perform all road tests and enter the checks again for the required items.AT- 5 3
7❏ For any remaining NG items, perform the “diagnostics procedure” and repair or replace the malfunction parts.
See the chart for diagnostics by symptoms. (This chart also contains other symptoms and inspection proce-
dures.)AT- 6 0
8❏ Erase the results of the self-diagnostics from the TCM.AT- 3 8

AT-48
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A/T Electrical Parts LocationECS00CEC
WCIA0515E

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Circuit DiagramECS00CED
BCWA0409E