2006 INFINITI FX35 engine control system

A/T CONTROL SYSTEM AT-37
D E
F
G H
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M A
B
AT
Revision: 2006 December 2006 FX35/FX45
Lock-up ControlNCS001B4
The torque converter clutch piston in the torque converter is engaged to eliminate torque converter slip to
increase power transmission efficiency.
The torque converter clutch control valve operation is controlled by the torque converter clutch solenoid valve,
which is controlled by a signal from TCM, and the torque converter clutch control valve engages or releases
the torque converter clutch piston.
Lock-up Operation Condition Table
TORQUE CONVERTER CLUTCH CONTROL VALVE CONTROL
Lock-up Control System Diagram
Lock-up Released
In the lock-up released state, the torque converter clutch control valve is set into the unlocked state by the
torque converter clutch solenoid and the lock-up apply pressure is drained.
In this way, the torque converter clutch piston is not coupled.
Lock-up Applied
In the lock-up applied state, the torque converter clutch control valve is set into the locked state by the torque
converter clutch solenoid and lock-up apply pressure is generated.
In this way, the torque converter clutch piston is pressed and coupled.
SMOOTH LOCK-UP CONTROL
When shifting from the lock-up released state to the lock-up applied state, the current output to the torque con-
verter clutch solenoid is controlled with the TCM. In this way, when shifting to the lock-up applied state, the
torque converter clutch is temporarily set to the half-clutched state to reduce the shock.
Half-clutched State
The current output from the TCM to the torque converter clutch solenoid is varied to gradually increase the
torque converter clutch solenoid pressure.
In this way, the lock-up apply pressure gradually rises and while the torque converter clutch piston is put into
half-clutched status, the torque converter clutch piston operating pressure is increased and the coupling is
completed smoothly.
Slip Lock-up Control
In the slip region, the torque converter clutch solenoid current is controlled with the TCM to put it into the half-
clutched state. This absorbs the engine torque fluctuation and lock-up operates from low speed.
selector lever D position M5 position M4 position M3 position
Gear position 54543
Lock-up ×–×××
Slip lock-up ××–––
PCIA0014E

AT-38
A/T CONTROL SYSTEM
Revision: 2006 December 2006 FX35/FX45
Engine Brake ControlNCS001B5

The forward one-way clutch transmits the drive force from the engine to the rear wheels. But the reverse
drive from the rear wheels is not transmitted to the engine because the one-way clutch is idling.
Therefore, the low coast brake solenoid is operated to prevent the forward one-way clutch from idling and
the engine brake is operated in the same manner as conventionally.

The operation of the low coast brake solenoid switches the low coast brake switching valve and controls
the coupling and releasing of the low coast brake.
The low coast brake reducing valve controls the low coast brake coupling force.
Control ValveNCS001B6
FUNCTION OF CONTROL VALVE
SCIA1520E
Name Function
Torque converter regulator valve In order to prevent the pressure supplied to the torque converter from being excessive,
the line pressure is adjusted to the optimum pressure (torque converter operating pres-
sure).
Pressure regulator valve
Pressure regulator plug
Pressure regulator sleeve Adjusts the oil discharged from the oil pump to the optimum pressure (line pressure) for
the driving state.
Front brake control valve When the front brake is coupled, adjusts the line pressure to the optimum pressure
(front brake pressure) and supplies it to the front brake. (In 1st, 2nd, 3rd, and 5th gears,
adjusts the clutch pressure.)
Accumulator control valve Adjusts the pressure (accumulator control pressure) acting on the accumulator piston
and low coast reducing valve to the pressure appropriate to the driving state.
Pilot valve A Adjusts the line pressure and produces the constant pressure (pilot pressure) required
for line pressure control, shift change control, and lock-up control.
Pilot valve B Adjusts the line pressure and produces the constant pressure (pilot pressure) required
for shift change control.
Low coast brake switching valve During engine braking, supplies the line pressure to the low coast brake reducing valve.
Low coast brake reducing valve When the low coast brake is coupled, adjusts the line pressure to the optimum pressure
(low coast brake pressure) and supplies it to the low coast brake.
N-R accumulator Produces the stabilizing pressure for when N-R is selected.
Direct clutch piston switching valve Operates in 4th gear and switches the direct clutch coupling capacity.
High and low reverse clutch control valve When the high and low reverse clutch is coupled, adjusts the line pressure to the opti-
mum pressure (high and low reverse clutch pressure) and supplies it to the high and low
reverse clutch. (In 1st, 3rd, 4th and 5th gears, adjusts the clutch pressure.)

AT-44
TROUBLE DIAGNOSIS
Revision: 2006 December 2006 FX35/FX45
TROUBLE DIAGNOSISPFP:00004
DTC Inspection Priority ChartNCS001BC
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 CAN
COMMUNICATION. Refer to AT- 1 0 4
.
Fail-safeNCS001BD
The TCM has an electrical fail-safe mode. This mode makes it possible to operate even if there is a an error in
a main electronic control input/output signal circuit.
In fail-safe mode, even if the selector lever is “D” or “M” 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
“WORK FLOW” (Refer to AT- 4 7
).
FAIL-SAFE FUNCTION
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 trans-
mission 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 and manual mode
are prohibited.
Accelerator Pedal Position Sensor
If there is a malfunction in one of the systems, the accelerator opening angle is controlled by ECM according
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 according
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 indi-
cating 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” position 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

AT-46
TROUBLE DIAGNOSIS
Revision: 2006 December 2006 FX35/FX45
How to Perform Trouble Diagnosis for Quick and Accurate RepairNCS001BE
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- 4 7 , "
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 8
) 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.
SAT631IB
SAT632I
SEF234G

AT-72
TROUBLE DIAGNOSIS
Revision: 2006 December 2006 FX35/FX45
23 Slips/Will
Not
Engage Vehicle cannot be
started from D
1 .
Refer to AT-201,
"Vehicle Cannot Be
Started From D1" . ON vehicle
1. A/T fluid level and state
AT- 5 3
2. Accelerator pedal position sensorAT- 1 3 1
3. Line pressure test AT- 5 4
4. CAN communication lineAT- 1 0 4
5. Control valve with TCMAT- 2 3 9
OFF vehicle 6. Torque converter
AT- 2 9 4
7. Oil pump assemblyAT- 3 1 2
8. 3rd one-way clutchAT- 3 1 5
9. 1st one-way clutch AT- 3 2 3
10. Gear systemAT- 2 7 4
11. Reverse brakeAT- 2 9 4
12. Forward one-way clutch (Parts behind drum support is
impossible to perform inspection by disassembly. Refer to
AT-18, "
Cross-sectional View (2WD Models)" , AT- 1 9 ,
"Cross-sectional View (VQ35DE Models for AWD)" or AT-
20, "Cross-sectional View (VK45DE Models for AWD)" ) AT- 2 9 4
13. Forward brake (Parts behind drum support is impossible
to perform inspection by disassembly. Refer to AT-18,
"Cross-sectional View (2WD Models)" , AT-19, "Cross-sec-
tional View (VQ35DE Models for AWD)" or AT- 2 0 , "Cross-
sectional View (VK45DE Models for AWD)" ) AT- 2 9 4
24
Does not lock-up.
Refer to AT-213, "A/T
Does Not Lock-up" . ON vehicle 1. A/T fluid level and state
AT- 5 3
2. Line pressure testAT- 5 4
3. Engine speed signalAT- 1 2 3
4. Turbine revolution sensor AT- 11 6
5. Torque converter clutch solenoid valveAT- 1 2 5
6. CAN communication lineAT- 1 0 4
7. Control valve with TCMAT- 2 3 9
OFF vehicle 8. Torque converter
AT- 2 9 49. Oil pump assemblyAT- 3 1 2
25 Does not hold lock-up
condition.
Refer to AT-215, "A/T
Does Not Hold Lock-
up Condition" . ON vehicle 1. A/T fluid level and state
AT- 5 3
2. Line pressure testAT- 5 4
3. Engine speed signalAT- 1 2 3
4. Turbine revolution sensor AT- 11 6
5. Torque converter clutch solenoid valveAT- 1 2 5
6. CAN communication lineAT- 1 0 4
7. Control valve with TCMAT- 2 3 9
OFF vehicle 8. Torque converter
AT- 2 9 49. Oil pump assemblyAT- 3 1 2
No. Items Symptom Condition Diagnostic Item Reference
page

TROUBLE DIAGNOSIS AT-73
D E
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G H
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K L
M A
B
AT
Revision: 2006 December 2006 FX35/FX4526 Slips/Will
Not
Engage Lock-up is not
released.
Refer to AT-217,
"Lock-up Is Not
Released" . ON vehicle 1. A/T fluid level and state
AT- 5 3
2. Line pressure testAT- 5 4
3. Engine speed signalAT-123
4. Turbine revolution sensor AT- 11 6
5. Torque converter clutch solenoid valveAT-125
6. CAN communication lineAT-104
7. Control valve with TCMAT-239
OFF vehicle 8. Torque converter
AT-2949. Oil pump assemblyAT-312
27 No shock at all or the
clutch slips when
vehicle changes
speed D
1 → D2 or
M
1 → M2 . ON vehicle
1. A/T fluid level and state
AT- 5 3
2. Vehicle speed sensor A/T and vehicle speed sensor MTR AT- 11 8,
AT-139
3. ATF pressure switch 5 and direct clutch solenoid valve AT-175,
AT-154
4. CAN communication line AT-104
5. Line pressure test AT- 5 4
6. Control valve with TCMAT-239
OFF vehicle 7. Torque converter
AT-294
8. Oil pump assemblyAT-312
9. 3rd one-way clutchAT-315
10. Gear systemAT-274
11. Direct clutchAT-332
12. Forward brake (Parts behind drum support is impossible
to perform inspection by disassembly. Refer to AT-18,
"Cross-sectional View (2WD Models)" , AT- 1 9 , "Cross-sec-
tional View (VQ35DE Models for AWD)" or AT-20, "Cross-
sectional View (VK45DE Models for AWD)" ) AT-294
No. Items Symptom Condition Diagnostic Item
Reference
page

TROUBLE DIAGNOSIS AT-75
D E
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G H
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K L
M A
B
AT
Revision: 2006 December 2006 FX35/FX45
30 Slips/Will
Not
Engage No shock at all or the
clutch slips when
vehicle changes
speed D
4 → D5 or
M
4 → M5 . ON vehicle
1. A/T fluid level and state
AT- 5 3
2. Vehicle speed sensor A/T and vehicle speed sensor MTR AT- 11 8,
AT-139
3. ATF pressure switch 1 and front brake solenoid valve AT-171,
AT-150
4. ATF pressure switch 5 and direct clutch solenoid valve AT-175,
AT-154
5. CAN communication line AT-104
6. Line pressure test AT- 5 4
7. Control valve with TCMAT-239
OFF vehicle 8. Torque converter
AT-294
9. Oil pump assemblyAT-312
10. Front brake (brake band)AT-294
11. Input clutchAT-317
12. Gear systemAT-274
13. High and low reverse clutchAT-329
31 When you press the
accelerator pedal and
shift speed D5 → D4
or M
5 → M4 the
engine idles or the A/
T slips. ON vehicle
1. A/T fluid level and state
AT- 5 3
2. Vehicle speed sensor A/T and vehicle speed sensor MTR AT- 11 8,
AT-139
3. ATF pressure switch 1 and front brake solenoid valve AT-171,
AT-150
4. ATF pressure switch 5 and direct clutch solenoid valve AT-175,
AT-154
5. CAN communication line AT-104
6. Line pressure test AT- 5 4
7. Control valve with TCMAT-239
OFF vehicle 8. Torque converter
AT-294
9. Oil pump assemblyAT-312
10. Input clutchAT-317
11. Gear systemAT-274
12. High and low reverse clutchAT-329
13. Direct clutchAT-332
No. Items Symptom Condition Diagnostic Item Reference
page

AT-76
TROUBLE DIAGNOSIS
Revision: 2006 December 2006 FX35/FX45
32 Slips/Will
Not
Engage When pressing the
accelerator pedal and
shifting speed D4 →
D
3 or M4 → M3 the
engine idles or the A/
T slips. ON vehicle
1. A/T fluid level and state
AT- 5 3
2. Vehicle speed sensor A/T and vehicle speed sensor MTR AT- 11 8,
AT- 1 3 9
3. ATF pressure switch 3 and input clutch solenoid valve AT- 1 7 3,
AT- 1 4 6
4. ATF pressure switch 1 and front brake solenoid valve AT- 1 7 1,
AT- 1 5 0
5. CAN communication line AT- 1 0 4
6. Line pressure test AT- 5 4
7. Control valve with TCMAT- 2 3 9
OFF vehicle 8. Torque converter
AT- 2 9 4
9. Oil pump assemblyAT- 3 1 2
10. 3rd one-way clutchAT- 3 1 5
11. Gear systemAT- 2 7 4
12. High and low reverse clutchAT- 3 2 9
13. Forward one-way clutch (Parts behind drum support is
impossible to perform inspection by disassembly. Refer to
AT-18, "
Cross-sectional View (2WD Models)" , AT- 1 9 ,
"Cross-sectional View (VQ35DE Models for AWD)" or AT-
20, "Cross-sectional View (VK45DE Models for AWD)" ) AT- 2 9 4
14. Forward brake (Parts behind drum support is impossible
to perform inspection by disassembly. Refer to AT-18,
"Cross-sectional View (2WD Models)" , AT-19, "Cross-sec-
tional View (VQ35DE Models for AWD)" or AT- 2 0 , "Cross-
sectional View (VK45DE Models for AWD)" ) AT- 2 9 4
33 When pressing the
accelerator pedal and
shifting speed D3 →
D
2 or M3 → M2 the
engine idles or the A/
T slips. ON vehicle
1. A/T fluid level and state
AT- 5 3
2. Vehicle speed sensor A/T and vehicle speed sensor MTR AT- 11 8,
AT- 1 3 9
3. ATF pressure switch 6, high and low reverse clutch sole-
noid valve AT- 1 7 7,
AT- 1 5 8
4. ATF pressure switch 5 and direct clutch solenoid valve AT- 1 7 5,
AT- 1 5 4
5. CAN communication line AT- 1 0 4
6. Line pressure test AT- 5 4
7. Control valve with TCMAT- 2 3 9
OFF vehicle 8. Torque converter
AT- 2 9 4
9. Oil pump assemblyAT- 3 1 2
10. 3rd one-way clutch AT- 3 1 5
11. Gear systemAT- 2 7 4
12. Direct clutchAT- 3 3 2
13. Forward brake (Parts behind drum support is impossible
to perform inspection by disassembly. Refer to AT-18,
"Cross-sectional View (2WD Models)" , AT-19, "Cross-sec-
tional View (VQ35DE Models for AWD)" or AT- 2 0 , "Cross-
sectional View (VK45DE Models for AWD)" ) AT- 2 9 4
No. Items Symptom Condition Diagnostic Item
Reference
page