A/T CONTROL SYSTEM
AT-31
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Revision: 2006 January2006 M35/M45
TCM FunctionNCS001JP
The function of the TCM is to:
Receive input signals sent from various switches and sensors.
Determine required line pressure, shifting point, lock-up operation, and engine brake operation.
Send required output signals to the respective solenoids.
CONTROL SYSTEM OUTLINE
The A/T senses vehicle operating conditions through various sensors or signals. It always controls the opti-
mum shift position and reduces shifting and lock-up shocks.
CONTROL SYSTEM DIAGRAM
SENSORS (or SIGNAL)TCMACTUATORS
PNP switch
Accelerator pedal position signal
Closed throttle position signal
Wide open throttle position signal
Engine speed signal
A/T fluid temperature sensor
Revolution sensor
Vehicle speed signal
Manual mode switch signal
Stop lamp switch signal
Turbine revolution sensor
ATF pressure switchShift control
Line pressure control
Lock-up control
Engine brake control
Timing control
Fail-safe control
Self-diagnosis
CONSULT-II communication line
Duet-EA control
CAN systemInput clutch solenoid valve
Direct clutch solenoid valve
Front brake solenoid valve
High and low reverse clutch
solenoid valve
Low coast brake solenoid valve
Torque converter clutch solenoid
valve
Line pressure solenoid valve
A/T CHECK indicator lamp
Back-up lamp relay
Sta r te r re l a y
SCIA5325E
AT-32
A/T CONTROL SYSTEM
Revision: 2006 January2006 M35/M45
CAN CommunicationNCS001JQ
SYSTEM DESCRIPTION
CAN (Controller Area Network) is a serial communication line for real time application. It is an on-vehicle mul-
tiplex communication line with high data communication speed and excellent error detection ability. Many elec-
tronic control units are equipped onto a vehicle, and each control unit shares information and links with other
control units during operation (not independent). In CAN communication, control units are connected with 2
communication lines (CAN H line, CAN L line) allowing a high rate of information transmission with less wiring.
Each control unit transmits/receives data but selectively reads required data only. Refer to LAN-34, "
CAN
Communication Unit" .
Input/Output Signal of TCMNCS001JR
*1: Spare for vehicle speed sensorꞏA/T (revolution sensor)
*2: Spare for accelerator pedal position signal
*3: If these input and output signals are different, the TCM triggers the fail-safe function.
*4: Used as a condition for starting self-diagnostics; if self-diagnostics are not started, it is judged that there is some kind of error.
*5: Input by CAN communications.
*6: Output by CAN communications.Control itemLine
pressure
controlVehicle
speed
controlShift
controlLock-up
controlEngine
brake
controlFail-safe
function
(*3)Self-diag-
nostics
function
InputAccelerator pedal position signal
(*5)XXXXXXX
Vehicle speed sensor A/T
(revolution sensor)XXXXXXX
Vehicle speed sensor MTR
(*1) (*5)X
Closed throttle position signal
(*5)X(*2) X X X X(*4)
Wide open throttle position signal
(*5)XX(*4)
Turbine revolution sensor 1 X X X X X
Turbine revolution sensor 2
(for 4th speed only)X XXXX
Engine speed signals
(*5)XXXXXXX
Stop lamp switch signal
(*5)XXX X(*4)
A/T fluid temperature sensors 1, 2XXXX XX
ASCD or ICC
sensor inte-
grated unitOperation signal
(*5)XXX
Overdrive cancel
signal
(*5)X
Out-
putDirect clutch solenoid
(ATF pressure switch 5)XX XX
Input clutch solenoid
(ATF pressure switch 3)XX XX
High and low reverse clutch solenoid
(ATF pressure switch 6)XX XX
Front brake solenoid
(ATF pressure switch 1)XX XX
Low coast brake solenoid
(ATF pressure switch 2)XX XXX
Line pressure solenoidXXXXXXX
TCC solenoid X X X
Self-diagnostics table
(*6)X
Starter relayXX
AT-34
A/T CONTROL SYSTEM
Revision: 2006 January2006 M35/M45
During Shift Change
The necessary and adequate line pressure for shift change is set.
For this reason, line pressure pattern setting corresponds to input
torque and gearshift selection. Also, line pressure characteristic is
according to engine speed, during engine brake operation.
At Low Fluid Temperature
When the A/T fluid temperature drops below the prescribed tempera-
ture, in order to speed up the action of each friction element, the line
pressure is set higher than the normal line pressure characteristic.
Shift ControlNCS001JT
The clutch pressure control solenoid is controlled by the signals from the switches and sensors. Thus, the
clutch pressure is adjusted to be appropriate to the engine load state and vehicle driving state. It becomes
possible to finely control the clutch hydraulic pressure with high precision and a smoother shift change charac-
teristic is attained.
PCIA0010E
PCIA0011E
PCIA0012E
AT-36
A/T CONTROL SYSTEM
Revision: 2006 January2006 M35/M45
Shift Change System Diagram
ASC (ADOPTIVE SHIFT CONTROL)
ASC automatically shifts or hold at the 3rd or 4th gear on certain roads (up/down slope and curve) and driving
condition.
When Driving on an Up/down Slope
ASC judges up/down slope according to the angle of accelerator pedal and vehicle speed. Holding gear at
the 3rd or 4th on an up-slope prevents shift hunting and controls the vehicle to gain maximum driving
force. On a down-slope, automatic shift-down to the 3rd or 4th gear controls to gain maximum engine
brake.
When Driving on a Curve
TCM receives side G sensor signal from ABS actuator and electric unit (control unit). Holding gear at the
3rd or 4th based on the signal prevents shift-up and kick-down and controls to drive smoothly.
SCIA6483E
SCIA6469E
AT-40
ON BOARD DIAGNOSTIC (OBD) SYSTEM
Revision: 2006 January2006 M35/M45
ON BOARD DIAGNOSTIC (OBD) SYSTEMPFP:00028
IntroductionNCS001JX
The A/T system has two self-diagnostic systems.
The first is the emission-related on board diagnostic system (OBD-II) performed by the TCM in combination
with the ECM. The malfunction is indicated by the MIL (malfunction indicator lamp) and is stored as a DTC in
the ECM memory but not the TCM memory.
The second is the TCM original self-diagnosis indicated by the A/T CHECK indicator lamp. The malfunction is
stored in the TCM memory. The detected items are overlapped with OBD-II self-diagnostic items. For detail,
refer to AT- 9 2 , "
Display Items List" .
OBD-II Function for A/T SystemNCS001JY
The ECM provides emission-related on board diagnostic (OBD-II) functions for the A/T system. One function
is to receive a signal from the TCM used with OBD-related parts of the A/T system. The signal is sent to the
ECM when a malfunction occurs in the corresponding OBD-related part. The other function is to indicate a
diagnostic result by means of the MIL (malfunction indicator lamp) on the instrument panel. Sensors, switches
and solenoid valves are used as sensing elements.
The MIL automatically illuminates in “One or Two Trip Detection Logic” when a malfunction is sensed in rela-
tion to A/T system parts.
One or Two Trip Detection Logic of OBD-IINCS001JZ
ONE TRIP DETECTION LOGIC
If a malfunction is sensed during the first test drive, the MIL will illuminate and the malfunction will be stored in
the ECM memory as a DTC. The TCM is not provided with such a memory function.
TWO TRIP DETECTION LOGIC
When a malfunction is sensed during the first test drive, it is stored in the ECM memory as a 1st trip DTC
(diagnostic trouble code) or 1st trip freeze frame data. At this point, the MIL will not illuminate. — 1st trip
If the same malfunction as that experienced during the first test drive is sensed during the second test drive,
the MIL will illuminate. — 2nd trip
The “Trip” in the “One or Two Trip Detection Logic” means a driving mode in which self-diagnosis is performed
during vehicle operation.
OBD-II Diagnostic Trouble Code (DTC)NCS001K0
HOW TO READ DTC AND 1ST TRIP DTC
DTC and 1st trip DTC can be read by the following methods.
( with CONSULT-II or GST) CONSULT-II or GST (Generic Scan Tool) Examples: P0705, P0720 etc.
These DTC are prescribed by SAE J2012.
(CONSULT-II also displays the malfunctioning component or system.)
1st trip DTC No. is the same as DTC No.
Output of the diagnostic trouble code indicates that the indicated circuit has a malfunction. How-
ever, in case of the Mode II and GST, they do not indicate whether the malfunction is still occurring
or occurred in the past and returned to normal.
CONSULT-II can identify them as shown below, therefore, CONSULT-II (if available) is recom-
mended.
A sample of CONSULT-II display for DTC and 1st trip DTC is shown
on the next page. DTC or 1st trip DTC of a malfunction is displayed
in SELF-DIAGNOSTIC RESULTS mode for “ENGINE” with CON-
SULT-II. Time data indicates how many times the vehicle was driven
after the last detection of a DTC.
BCIA0030E
AT-44
TROUBLE DIAGNOSIS
Revision: 2006 January2006 M35/M45
TROUBLE DIAGNOSISPFP:00004
DTC Inspection Priority ChartNCS001K2
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 DTC, first perform the trouble diagnosis for “DTC U1000 CAN
COMMUNICATION LINE”. Refer to AT- 1 0 5
.
Fail-safeNCS001K3
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, even if the selector lever is “D” or “M” mode, the A/T is fixed in 2nd, 4th and 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 A/T 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 A/
T 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 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” 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
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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 A/T 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, the A/T is 4th gear.
High and Low Reverse Clutch Solenoid
If a (electrical or functional) malfunction 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 pro-
hibited.
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
AT-46
TROUBLE DIAGNOSIS
Revision: 2006 January2006 M35/M45
How to Perform Trouble Diagnosis for Quick and Accurate RepairNCS001K4
INTRODUCTION
The TCM receives a signal from the vehicle speed sensor, accelera-
tor 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