2001 INFINITI QX4 clutch

ª11º Position=NBAT0012S0406
Forward clutch
Forward one-way clutch
Overrun clutch
Low and reverse brakeAs overrun clutch engages, rear internal gear is locked by the operation of low and
reverse brake.
This is different from that of D
1and 21.
Engine brake Overrun clutch always engages, therefore engine brake can be obtained when decelerat-
ing.
SAT100J
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OVERALL SYSTEM
Shift Mechanism (Cont'd)
AT-19

ªD1º and ª21º Positions=NBAT0012S0402
Forward one-way clutch
Forward clutch
Low one-way clutchRear internal gear is locked to rotate counterclockwise because of the functioning of
these three clutches. (Start-up at D
1)
Overrun clutch
engagement conditions
(Engine brake)D
1: Overdrive control switch in ªOFFº
Throttle opening less than 3/16
2
1: Throttle opening less than 3/16
At D
1and 21positions, engine brake is not activated due to free turning of low one-way
clutch.
SAT096J
OVERALL SYSTEM
Shift Mechanism (Cont'd)
AT-20

ªD2º, ª22º and ª12º Positions=NBAT0012S0403
Forward clutch
Forward one-way clutch
Brake bandRear sun gear drives rear planetary carrier and combined front internal gear. Front inter-
nal gear now rotates around front sun gear accompanying front planetary carrier.
As front planetary carrier transfers the power to rear internal gear through forward clutch
and forward one-way clutch, this rotation of rear internal gear increases the speed of
rear planetary carrier compared with that of the 1st speed.
Overrun clutch
engagement conditionsD
2: Overdrive control switch in ªOFFº
Throttle opening less than 3/16
2
2: Throttle opening less than 3/16
1
2: Always engaged
SAT097J
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LC
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FE
TF
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OVERALL SYSTEM
Shift Mechanism (Cont'd)
AT-21

ªD3º Position=NBAT0012S0404
High clutch
Forward clutch
Forward one-way clutchInput power is transmitted to front planetary carrier through high clutch. And front plan-
etary carrier is connected to rear internal gear by operation of forward clutch and forward
one-way clutch.
This rear internal gear rotation and another input (the rear sun gear) accompany rear
planetary carrier to turn at the same speed.
Overrun clutch
engagement conditionsD
3: Overdrive control switch in ªOFFº
Throttle opening less than 3/16
SAT098J
OVERALL SYSTEM
Shift Mechanism (Cont'd)
AT-22

ªD4º (OD) Position=NBAT0012S0405
High clutch
Brake band
Forward clutch
(Does not affect power transmission)Input power is transmitted to front carrier through high clutch.
This front planetary carrier turns around the sun gear which is fixed by brake band and
makes front internal gear (output) turn faster.
Engine brake At D
4position, there is no one-way clutch in the power transmission line and engine
brake can be obtained when decelerating.
SAT099J
GI
MA
EM
LC
EC
FE
TF
PD
AX
SU
BR
ST
RS
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HA
SC
EL
IDX
OVERALL SYSTEM
Shift Mechanism (Cont'd)
AT-23

ªRº Position=NBAT0012S0407
Reverse clutch
Low and reverse brakeFront planetary carrier is stationary because of the operation of low and reverse brake.
Input power is transmitted to front sun gear through reverse clutch, which drives front
internal gear in the opposite direction.
Engine brake As there is no one-way clutch in the power transmission line, engine brake can be
obtained when decelerating.
SAT101J
OVERALL SYSTEM
Shift Mechanism (Cont'd)
AT-24

Control System=NBAT0013OUTLINENBAT0013S01The automatic transmission senses vehicle operating conditions through various sensors. It always controls
the optimum shift position and reduces shifting and lock-up shocks.
SENSORS
ETCM
EACTUATORS
PNP switch
Throttle position sensor
Closed throttle position switch
Wide open throttle position switch
Engine speed signal
A/T fluid temperature sensor
Revolution sensor
Vehicle speed sensor
Overdrive control switch
ASCD control unit
Stop lamp switch
Turbine revolution sensorShift control
Line pressure control
Lock-up control
Overrun clutch control
Timing control
Fail-safe control
Self-diagnosis
CONSULT-II communication
line
Duet-EU controlShift solenoid valve A
Shift solenoid valve B
Overrun clutch solenoid valve
Torque converter clutch sole-
noid valve
Line pressure solenoid valve
O/D OFF indicator lamp
T/F control unit
CONTROL SYSTEMNBAT0013S02
SAT125K
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FE
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PD
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SU
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OVERALL SYSTEM
Control System
AT-25

TCM FUNCTION=NBAT0013S03The function of the TCM is to:
IReceive input signals sent from various switches and sensors.
IDetermine required line pressure, shifting point, lock-up operation, and engine brake operation.
ISend required output signals to the respective solenoids.
INPUT/OUTPUT SIGNAL OF TCMNBAT0013S04
Sensors and solenoid valves Function
InputPNP switch Detects select lever position and sends a signal to TCM.
Throttle position sensor Detects throttle valve position and sends a signal to TCM.
Closed throttle position switch Detects throttle valve's fully-closed position and sends a signal to TCM.
Wide open throttle position switchDetects a throttle valve position of greater than 1/2 of full throttle and sends
a signal to TCM.
Engine speed signal From ECM.
A/T fluid temperature sensor Detects transmission fluid temperature and sends a signal to TCM.
Revolution sensor Detects output shaft rpm and sends a signal to TCM.
Vehicle speed sensorUsed as an auxiliary vehicle speed sensor. Sends a signal when revolution
sensor (installed on transmission) malfunctions.
Overdrive control switchSends a signal, which prohibits a shift to ªD
4º (overdrive) position, to the
TCM.
ASCD control unitSends the cruise signal and ªD
4º (overdrive) cancellation signal from ASCD
control unit to TCM.
Turbine revolution sensor Sends an input shaft revolution signal.
Stop lamp switch Sends the lock-up release signal to the TCM at time of D
4(lock-up).
OutputShift solenoid valve A/BSelects shifting point suited to driving conditions in relation to a signal sent
from TCM.
Line pressure solenoid valveRegulates (or decreases) line pressure suited to driving conditions in rela-
tion to a signal sent from TCM.
Torque converter clutch solenoid
valveRegulates (or decreases) lock-up pressure suited to driving conditions in
relation to a signal sent from TCM.
Overrun clutch solenoid valveControls an ªengine brakeº effect suited to driving conditions in relation to a
signal sent from TCM.
O/D OFF indicator lamp Shows TCM faults, when A/T control components malfunction.
Control MechanismNBAT0180LINE PRESSURE CONTROLNBAT0180S01TCM has the various line pressure control characteristics to meet
the driving conditions.
An ON-OFF duty signal is sent to the line pressure solenoid valve
based on TCM characteristics.
Hydraulic pressure on the clutch and brake is electronically con-
trolled through the line pressure solenoid valve to accommodate
engine torque. This results in smooth shift operation.
OVERALL SYSTEM
Control System (Cont'd)
AT-26