Description
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14-3
The automatic transmission is a combination of a 3-element torque converter and triple-shalt electronically controlled
automatic transmission which provides 4 speeds forward and 1 speed reverse. The entire unit is positioned in line with
the engrne.
Torque Converter, Gears, and Clutches
The torque converter consists of a pump, turbine, and stator, assembled in sigle unit. The torque converter is connected to
the engine crankshaft so they turn torether as a unit as the engine turns. Around the outside of the torque convener is a
ring gear which meshes with the starter pinion when the engine is being started. The entire torque converter assembly
serves as a flywheel while transmitting power to the transmission mainshaft.
The transmission has three parallel shafts; the mainshaft. the countershaft, and the sub shaft. The mainshaft is in-line with
the engine crankshaft.
The mainshaft includes the 1st, and 2ndl4th clutches,and gear for 3rd, 2nd, 4th, reverse, and 1st. (3rd gear is integral with
the mainshaft, while reverse gear is integral with the 4th gear.)
The countershaft includes the 3rd clutch and gears for 3rd,2nd, 4th, reverse, 1st, and parking. Reverse and 4th gears can
be loched to the countershaft at its center,providing 4th gear or reverse, depending on which way the selector is moved.
The sub-shaft includes the 1st-hold clutch and gears fo 1st and 4th.
The gears on the mainshaft are in constant mesh with those on the countersahft and sub-shaft.When certain combinations
of gears in the transmission are engaged by clutches. power in transmitted from the mainshaft to the countershaft via the
sub-shaft to orovude oil, lo'1. E, E. and E.
Electronic Control
The electronic control svstem consists of the Transmission Control Module (TCM), sensors, and four solenoid valves.
Shilting and lock-up are electronically controlled for comfortable driving under all conditions.
The TCM is located below the dashboard, behind the lelt side kick panel on the driver's side.
Hydraulic Control
The valve bodies include the main valve body, the secondary valve body, the regulator valve body, the serbvo body, and
the lock-up valve body, through the respective separator plates, They are bolted to the torque converter housing,
The main valve body contains the manual valve, the 1-2 shift valve, the 2-3 shitt valve, the Clutch Pressure Control
lCPC) valve, the 4th exhaust valve, the reliel valve, and the ATF pump gears.
The secondary valve body contains the 4-3 kick-down valve, the 3-2 kick-down valve, the 2-3 orifice control valve, the
3-4 shift valve, the orilice control valve, the modulator valve, and the servo control valve.
The regulator valve body contains the pressure regulator valve, the lock-up control valve, the torque converter check
valve, and the cooler check valve.
The servo body contains the servo valve, which is integrated with shift fork shaft, the throttle valve B, and the accumula-
tors.
The lock-up valve body contains the lock-up shift valve and the lock-up timing B valve, and is bolted to the regulator valve
ooqy.
Fluid from the regulator passes through the manual valve to the various control valves.
Shift Control Mechanism
Input to the TCM from various sensors located throughout the car determines which shift control solenoid valve should
be activated. Activating a shitt control solenoid valve changes modulator pressure, causing a shift valve to move. This
pressurizes a line to one ol the clutches, engaging that clutch and its corresponding gear.
Lock-uD Mechanism
In @ position, in 2nd, 3rd and 4th, and @ position in 3rd, pressurized fluid can be drained lrom the back oI the tor-
que converter through a fluid passage, causing the lock-up piston to be held against the torque converter cover. As this
takes place, the mainshaft rotates at the same speed as the engine crankshaft. Together with hydraulic control, the TCM
optimizes the timing of the lock-up mechanism.
The lock-up valves controlthe range of lock-up according to lock-up control solenoid valves A and B, and throttle valve B.
When lock-up control solenoid valves A and B activate, modulator pressure changes. Lock-up control solenoid valves
A and B are mounted on the torque converter housing, and are controlled by the TCM.
(cont'd)
Lock-uD Control
From sensor input signals, the TCM determines whether to turn the lock-up ON or OFF and activates lock-up control
solenoid valve A and/or B accordingiy. The combination oI driving signals to lock up control solenoid valves A and B
is shown in the table below.
ShiIt Contlol
The TCM instantaneously determines which gear should be selected by various signals sent from sensors, and actuates
the shift control solenoid valves A and B control shifting. Also, a Grade Logic Control System has been adopted to control
shifting in @ position while the vehicle is ascending or descending a slope, or reducing speed.
w"'u"
Lock-up condition
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Lock'up OFFOFFOFF
Lock-up, slightONOFF
Lock-up, halfONON
Lock up, fullONON
LOCK-Upduring decelerationONDuty operationOFF-ON
Shift control solenoid valve
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B
tc!t' tcll
{1st)OFFON
(2nd )ONON
(3rd)ONOFF
{4th)OFFOFF
e {2nd)ONON
tr (1st)ONOFF
tr (Reverse)ONOFF
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(cont'd)
14-19
Description
Elestronic Control System (cont'd)
. GRADE LOGIC CONTROL SYSTEM
How it works:
The TCM compares actual driving conditions with driving conditions memorized in the TCM. based on th€ input from the
vehicle speed sensor, throttle position sensor, engine coolant temperature sensor, barometric pressure sensor, bral(e
switch signal and shift lever position signal, to control shifting while a vehicle is ascending or descending a slope, or
reducing speed.
SIGNALS DETECTED
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Driving ResistanceJudgement of Controlling Aroa
. Ascending mode(Fuzzy logicl. Gl.dual Ascending mode' Steop Asconding mode' oesconding mode. Gradu.l D$conding modo. Slecp D$conding modo
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THROTTLErcsm0NSENSOR
ENGINECOOLANTTEMPERATURESENSOR
WHT/BLKBLK/RED
820424
OBNREO/BLK
84
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MAINSHAFI COUNTERSHAFISPEED SENSOR SPfED SENSOR
I SHIFT CONTROL I LOCK -UP CONTBOL
+135Eil,?1o'uo'u' 4i85El,o''P'uo'u'
TCM T6nninal locations
TCM -B l22P)Conn€ctor
VREF IATCHK IBASOSS IAFSA IAFSB IFAS ISCS
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+.. | +.., I + ,+
l+ | J l/vt-l .i{-'1M-l L-{-lr^/t-lt't'/!-?
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r--rr!\.1 -r!\./ rartsurssrot coNTFoL M'DULE tTcMr
ltEltn r' -rrt= t= t? t=
NMSG INC INCSG ISH A ISH B ILC A ILC B
576I101112578I10
151617,/1,/20251214,/1,/171920,/1,/J
TCM -A (26P1 Connector
14-47
