2007 INFINITI FX35 engine control

AT-36
A/T CONTROL SYSTEM
Revision: 2006 July 2007 FX35/FX45
Shift Change System Diagram
*1: Full phase real-time feedback control monitors movement of gear ratio at gear change, and controls oil
pressure at real-time to achieve the best gear ratio.
BLIPPING CONTROL
This system makes transmission clutch engage readily by controlling (synchronizing) engine revolution
according to the (calculation of) engine revolution after shifting down.

“BLIPPING CONTROL” functions.
–When downshifting by accelerator pedal depression at “D” position.
–When downshifting under the manual mode.

TCM selects “BLIPPING CONTROL” or “NORMAL SHIFT CONTROL” according to the gear position, the
select lever position, the engine torque and the speed when accelerating by accelerator pedal depression.

Revolution control demand signal is transmitted from TCM to ECM under “BLIPPING CONTROL”.

TCM synchronizes engine revolution according to the revolution control demand signal.
Shift Change System Diagram
PCIA0013E
SCIA6483E

A/T CONTROL SYSTEM AT-37
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Revision: 2006 July 2007 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 July 2007 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 July 2007 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 6
).
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

TROUBLE DIAGNOSIS AT-45
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Revision: 2006 July 2007 FX35/FX45
A/T Interlock

If there is an A/T interlock judgment malfunction, the A/T is fixed in 2nd gear to make driving possible.
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 malfunction (electrical or functional) occurs, in order to make driving possible, if the solenoid is ON,
the transmission is held in 2nd gear; if the solenoid is OFF, the A/T is held in 4th gear. (Engine brake is not
applied in 1st and 2nd gear.)
Input Clutch Solenoid
If a malfunction (electrical or functional) occurs with the solenoid either ON or OFF, the A/T is held in 4th gear
to make driving possible.
Direct Clutch Solenoid
If a malfunction (electrical or functional) occurs with the solenoid either ON or OFF, the A/T is held in 4th gear
to make driving possible.
Front Brake Solenoid
If a malfunction (electrical or functional) 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 malfunction (electrical or functional) occurs with the solenoid either ON or OFF, the A/T 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 and manual mode are prohib-
ited.
Gear position ATF pressure switch output
Fail-safe function Clutch 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 pattern 3rd – X X –

Held in
2nd gear OFF OFF ON OFF OFF OFF
4th – X X –
Held in
2nd gear OFF OFF ON OFF OFF OFF
5th X X – X
Held in
2nd gear OFF OFF ON OFF OFF OFF

AT-46
TROUBLE DIAGNOSIS
Revision: 2006 July 2007 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 6 , "
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.
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 7
) and “DIAGNOSTIC
WORKSHEET” (Refer to AT- 4 8
), to perform the best troubleshooting possible.
SAT631IB
SAT632I
SEF234G

AT-64
TROUBLE DIAGNOSIS
Revision: 2006 July 2007 FX35/FX45
Symptom ChartNCS001BP

The diagnostics item numbers show the sequence for inspection. Check in order from item 1.

Overhaul and check inside the A/T only if A/T fluid condition is NG. Refer to AT- 5 3 , "A/T Fluid Condition
Check" .
No. Items Symptom Condition Diagnostic Item Reference
page
1 Shift
Shock Large shock. (“N”
→
“D” position)
Refer to AT-193,
"Large Shock (“N” to
“D” Position)" . ON vehicle 1. Engine idle speed
EC-81
(for
VQ35DE)
or EC-743

(for
VK45DE)
2. Engine speed signal AT- 1 2 3
3. Accelerator pedal position sensorAT- 1 3 1
4. A/T positionAT- 2 3 1
5. A/T fluid temperature sensorAT- 1 3 4
6. ATF pressure switch 1 and front brake solenoid valve AT- 1 7 1,
AT- 1 5 0
7. CAN communication line AT- 1 0 4
8. A/T fluid level and state AT- 5 3
9. Line pressure testAT- 5 4
10. Control valve with TCMAT- 2 3 9
OFF vehicle 11. 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
2
Shock is too large
when changing D1 →
D
2 or M1 → M2 . ON vehicle 1. Accelerator pedal position sensor
AT- 1 3 1
2. A/T positionAT- 2 3 1
3. ATF pressure switch 5 and direct clutch solenoid valve AT- 1 7 5,
AT- 1 5 4
4. CAN communication line AT- 1 0 4
5. Engine speed signalAT- 1 2 3
6. Turbine revolution sensor AT- 11 6
7. Vehicle speed sensor A/T and vehicle speed sensor MTR AT- 11 8,
AT- 1 3 9
8. A/T fluid level and state AT- 5 3
9. Control valve with TCMAT- 2 3 9
OFF vehicle 10. Direct clutch AT- 3 3 2

TROUBLE DIAGNOSIS AT-65
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Revision: 2006 July 2007 FX35/FX45
3
Shift
Shock Shock is too large
when changing D2 →
D
3 or M2 → M3 . ON vehicle 1. Accelerator pedal position sensor
AT-131
2. A/T positionAT-231
3. ATF pressure switch 6, high and low reverse clutch sole-
noid valve AT-177,
AT-158
4. CAN communication line AT-104
5. Engine speed signalAT-123
6. Turbine revolution sensor AT- 11 6
7. Vehicle speed sensor A/T and vehicle speed sensor MTR AT- 11 8,
AT-139
8. A/T fluid level and state AT- 5 3
9. Control valve with TCMAT-239
OFF vehicle 10. High and low reverse clutch AT-329
4 Shock is too large
when changing D3 →
D
4 or M3 → M4 . ON vehicle 1. Accelerator pedal position sensor
AT-131
2. A/T positionAT-231
3. ATF pressure switch 3 and input clutch solenoid valve AT-173,
AT-146
4. CAN communication line AT-104
5. Engine speed signalAT-123
6. Turbine revolution sensor AT- 11 6
7. Vehicle speed sensor A/T and vehicle speed sensor MTR AT- 11 8,
AT-139
8. A/T fluid level and state AT- 5 3
9. Control valve with TCMAT-239
OFF vehicle 10. Input clutch AT-317
5 Shock is too large
when changing D4 →
D
5 or M4 → M5 . ON vehicle 1. Accelerator pedal position sensor
AT-131
2. A/T positionAT-231
3. ATF pressure switch 1 and front brake solenoid valve AT-171,
AT-150

4. CAN communication line AT-104
5. Engine speed signalAT-123
6. Turbine revolution sensor AT- 11 6
7. Vehicle speed sensor A/T and vehicle speed sensor MTR AT- 11 8,
AT-139
8. A/T fluid level and state AT- 5 3
9. Control valve with TCMAT-239
OFF vehicle 10. Front brake (brake band)
AT-27411. Input clutchAT-317
No. Items Symptom Condition Diagnostic Item Reference
page