A/T CONTROL SYSTEM
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CAN CommunicationUCS005M D
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. For details, refer to LAN-47,
"CAN System Specification Chart" .
Input/Output Signal of TCMUCS005M E
*1: Spare for vehicle speed sensor·A/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-diagnosis 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
functionSelf-diag-
nostics
function
InputAccelerator pedal position signal
(*5)XXXXX(*3) XX
Vehicle speed sensor·A/T
(Revolution sensor)XXXXX(*3) XX
Vehicle speed sensor·MTR (*1) X (*1) X (*1) X (*1) X X
Closed throttle position signal
(*5)(*2) X(*2) XXX(*4) X
Wide open throttle position signal
(*5)(*2) X (*2) X (*4) X
Turbine revolution sensor (Power
train revolution sensor)XX X XX
Engine speed signal X X X X
PNP switch X X X X X (*3) X (*4) X
Stop lamp switch signal
(*5)XX (*4) X
A/T fluid temperature sensors
(*5)XXXX XX
Overdrive control switch signal
(*5)XXXX (*4) X
TCM power supply voltage signal X X X X
Out-
putShift solenoid valve A/B X (*3) X X
Line pressure solenoid X (*3) X X
Torque converter clutch solenoid
valveX(*3) XX
Overrun clutch solenoid valve X X (*3) X X
OD OFF indicator lamp
(*6)XX
A/T CONTROL SYSTEM
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AT LOW FLUID TEMPERATURE
A/T fluid viscosity and frictional characteristics of the clutch facing change with A/T fluid temperature.
Clutch engaging or band-contacting pressure is compensated for, according to A/T fluid temperature, to
stabilize shifting quality.
The line pressure is reduced below 60°C (140°F) to prevent
shifting shock due to high viscosity of A/T fluid when tempera-
ture is low.
Line pressure is increased to a maximum irrespective of the
throttle opening when A/T fluid temperature drops to −10°C
(14°F). This pressure rise is adopted to prevent a delay in clutch
and brake operation due to extreme drop of A/T fluid viscosity at
low temperature.
Shift ControlUCS005MG
The shift is regulated entirely by electronic control to accommodate vehicle speed and varying engine opera-
tions. This is accomplished by electrical signals transmitted by the revolution sensor and the ECM (accelerator
pedal position sensor). This results in improved acceleration performance and fuel economy.
CONTROL OF SHIFT SOLENOID VALVES A AND B
The TCM activates shift solenoid valves A and B according to sig-
nals from the accelerator pedal position sensor and revolution sen-
sor to select the optimum gear position on the basis of the shift
schedule memorized in the TCM.
The shift solenoid valve performs simple ON-OFF operation. When
set to “ON”, the drain circuit closes and pilot pressure is applied to
the shift valve.
RELATION BETWEEN SHIFT SOLENOID VALVES A AND B AND GEAR POSITIONS
SCIA4829E
SCIA4830E
SAT0 0 8J
Gear position 1 2 3 4
Shift solenoid valve A ON (Closed) OFF (Open) OFF (Open) ON (Closed)
Shift solenoid valve B ON (Closed) ON (Closed) OFF (Open) OFF (Open)
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A/T CONTROL SYSTEM
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CONTROL OF SHIFT VALVES A AND B
Pilot pressure generated by the operation of shift solenoid valves A and B is applied to the end face of shift
valves A and B.
The figure above shows the operation of shift valve B. When the shift solenoid valve is “ON”, pilot pressure
applied to the end face of the shift valve overcomes spring force, moving the valve upward.
Lock-up ControlUCS005MH
The torque converter clutch piston in the torque converter is locked to eliminate torque converter slip and to
increase power transmission efficiency. The solenoid valve is controlled by an ON-OFF duty signal sent from
the TCM. The signal is converted to an oil pressure signal which controls the torque converter clutch piston.
CONDITIONS FOR LOCK-UP OPERATION
When vehicle is driven in 3rd and 4th gear positions, vehicle speed and throttle opening are detected. If the
detected values fall within the lock-up zone memorized in the TCM, lock-up is performed.
TORQUE CONVERTER CLUTCH SOLENOID VALVE CONTROL
Lock-up Control System Diagram
SAT0 0 9J
OD ON OFF
Selector lever “D” position
Gear position D
4D3
Vehicle speed sensor More than set value
Accelerator pedal position signal Less than set opening
Closed throttle position signal OFF
A/T fluid temperature sensor More than 40°C (104°F)
SCIA5623E
ON BOARD DIAGNOSTIC (OBD) SYSTEM
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ON BOARD DIAGNOSTIC (OBD) SYSTEMPFP:00028
IntroductionUCS005N3
A/T system has two self-diagnostic systems.
The first is 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 OD OFF 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- 8 2 , "
SELF-DIAGNOSTIC RESULT MODE" .
OBD-II Function for A/T SystemUCS005N4
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 relation
to A/T system parts.
One or Two Trip Detection Logic of OBD-IIUCS005N5
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)UCS005N6
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.
SAT0 1 4K
TROUBLE DIAGNOSIS
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TROUBLE DIAGNOSISPFP:00004
DTC Inspection Priority ChartUCS005ML
If some DTCs are displayed at the same time, perform inspections one by one based on the following priority
chart.
NOTE:
If DTC “CAN COMM CIRCUIT” is displayed with other DTCs, first perform the trouble diagnosis for
DTC “CAN COMM CIRCUIT”. Refer to AT- 9 4
.
Fail-safeUCS005MM
The TCM has an electronic Fail-safe mode. This allows the vehicle to be driven even if a major electrical input/
output device circuit is damaged.
Under Fail-Safe, the vehicle always runs in third gear, even with a shift lever position of “1”, “2” or “D”. The cus-
tomer may complain of sluggish or poor acceleration.
Always follow the “AT - 4 6 , "
WORK FLOW" ”.
The SELF-DIAGNOSIS results will be as follows:
The first SELF-DIAGNOSIS will indicate damage to the vehicle speed sensor or the revolution sensor.
During the next SELF-DIAGNOSIS, performed after checking the sensor, no damages will be indicated.
FAI L-S AFE FUN CT ION
The following fail-safe functions allow vehicles to be driven even when sensor, switch or solenoid malfunction
occurs.
Vehicle Speed Sensor·A/T (Revolution Sensor)
Vehicle speed sensor·MTR signal is input from combination meter.
Accelerator Pedal Position Signal and Throttle Position Signal
TCM controls the throttle opening angle to a predetermined fixed position to enable driving if a malfunctioning
signal is input to TCM.
PNP Switch
When the multiple PNP switch signals are input to TCM, the priority of selector lever position becomes “D”,
“N”, “R”, “2” and “1” in order by internal TCM determination.
The use of 4th gear is inhibited until normal operation resumes. Because the hydraulic circuit of the control
valve is switched by manual valve according to the selector lever position, however, actual operating condition
of vehicle becomes as follows.
Priority Detected items
1 CAN communication line
2 Except above
Actual lever position PNP switch input signal Running status
“P” “P” position and other position signals P
“R” “R” position and other position signals R
“N” “N” position and other position signals N
“D” “D” position and other position signals D
1 ⇔D2 ⇔D3 ⇔D4
“2”“2” position and other position signals (Except “1” position) 21 ⇔22 ⇔23
“2” position and “1” position signals 21 ⇔22
“1”“1” position and other position signals (Except “2” position) 11 ⇔12 ⇔13
“1” position and “2” position signals 11 ⇔12
TROUBLE DIAGNOSIS
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How to Perform Trouble Diagnoses for Quick and Accurate RepairUCS005M N
INTRODUCTION
The TCM receives a signal from the vehicle speed sensor, accelera-
tor pedal 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 sig-
nalsent from sensing elements used with the OBD-related parts of
theA/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 malfunction that occurs intermittently rather than continuously. Most
intermittent malfunctions are caused by poor electric connections or improper wiring. In this case, careful
checking of suspected circuits may help prevent the replacement of good parts.
A visual check only, may not find the cause of the malfunctions. A
road test with CONSULT-II or a circuit tester connected should be
performed. Follow the AT-46, "
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 malfunctions, espe-
cially intermittent ones. Find out what symptoms are present and
under what conditions they occur. A “DIAGNOSTIC WORKSHEET”
like the example (AT- 4 7 , "
DIAGNOSTIC WORKSHEET" ) should be
used.
Start your diagnosis by looking for “conventional” malfunctions first.
This will help troubleshoot driveability malfunctions on an electroni-
cally controlled engine vehicle.
Also check related Service bulletins for information.
SAT6 3 1IA
SAT6 3 2I
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AT-48
TROUBLE DIAGNOSIS
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4.❏ Perform “Road Test”.AT- 5 8
4-1. “Check Before Engine is Started”AT- 5 8
❏ AT-198, "OD OFF Indicator Lamp Does Not Come On"
❏ Perform self-diagnosis. Enter checks for detected items. AT- 8 2 , AT- 9 0 .
❏ AT- 9 4 , "
DTC U1000 CAN COMMUNICATION LINE" .
❏ AT- 9 7 , "
DTC P0705 PARK/NEUTRAL POSITION (PNP) SWITCH" .
❏ AT-102, "
DTC P0710 A/T FLUID TEMPERATURE SENSOR CIRCUIT" .
❏ AT-107, "
DTC P0720 VEHICLE SPEED SENSOR·A/T (REVOLUTION SENSOR)" .
❏ AT- 11 3 , "
DTC P0725 ENGINE SPEED SIGNAL" .
❏ AT- 11 7 , "
DTC P0731 A/T 1ST GEAR FUNCTION"
❏ AT-121, "DTC P0732 A/T 2ND GEAR FUNCTION" .
❏ AT-124, "
DTC P0733 A/T 3RD GEAR FUNCTION" .
❏ AT-128, "
DTC P0734 A/T 4TH GEAR FUNCTION" .
❏ AT-134, "
DTC P0740 TORQUE CONVERTER CLUTCH SOLENOID VALVE" .
❏ AT-139, "
DTC P0744 A/T TCC S/V FUNCTION (LOCK-UP)" .
❏ AT-145, "
DTC P0745 LINE PRESSURE SOLENOID VALVE" .
❏ AT-151, "
DTC P0750 SHIFT SOLENOID VALVE A" .
❏ AT-156, "
DTC P0755 SHIFT SOLENOID VALVE B" .
❏ AT-161, "
DTC P1760 OVERRUN CLUTCH SOLENOID VALVE" .
❏ AT-166, "
DTC VEHICLE SPEED SENSOR MTR" .
❏ AT-170, "
DTC BATT/FLUID TEMP SEN (A/T FLUID TEMP SENSOR CIRCUIT AND TCM
POWER SOURCE)" .
❏ AT-176, "
DTC TURBINE REVOLUTION SENSOR" .
❏ AT-182, "
CONTROL UNIT (RAM), CONTROL UNIT (ROM)" .
❏ AT-183, "
MAIN POWER SUPPLY AND GROUND CIRCUIT" .
4-2. “Check at Idle”AT- 5 9
❏ AT-200, "Engine Cannot Be Started in “P” and “N” Position" .
❏ AT-201, "
In “P” Position, Vehicle Moves Forward or Backward When Pushed" .
❏ AT-201, "
In “N” Position, Vehicle Moves" .
❏ AT-202, "
Large Shock “N” → “R” Position" .
❏ AT-203, "
Vehicle Does Not Creep Backward in “R” Position" .
❏ AT-205, "
Vehicle Does Not Creep Forward in “D”, “2” or “1” Position" .
TROUBLE DIAGNOSIS
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4. 4-3. “Cruise Test”AT-6 1
Part 1
❏ AT-206, "
Vehicle Cannot Be Started from D1" .
❏ AT-208, "
A/T Does Not Shift: D1 → D2 or Does Not Kickdown: D4 → D2" .
❏ AT-210, "
A/T Does Not Shift: D2 → D3" .
❏ AT-212, "
A/T Does Not Shift: D3 → D4" .
❏ AT-214, "
A/T Does Not Perform Lock-up" .
❏ AT-215, "
A/T Does Not Hold Lock-up Condition" .
❏ AT-216, "
Lock-up Is Not Released" .
❏ AT-217, "
Engine Speed Does Not Return to Idle (Light Braking D4 → D3 )" .
Part 2AT-6 4
❏ AT-206, "Vehicle Cannot Be Started from D1" .
❏ AT-208, "
A/T Does Not Shift: D1 → D2 or Does Not Kickdown: D4 → D2" .
❏ AT-210, "
A/T Does Not Shift: D2 → D3" .
❏ AT-212, "
A/T Does Not Shift: D3 → D4" .
Part 3AT-6 5
❏ AT-218, "A/T Does Not Shift: D4 → D3 , When OD OFF" .
❏ AT-219, "
A/T Does Not Shift: D3 → 22 , When Selector Lever “D” → “2” Position" .
❏ AT-221, "
A/T Does Not Shift: 22 → 11 , When Selector Lever “2” → “1” Position" .
❏ AT-223, "
Vehicle Does Not Decelerate by Engine Brake" .
❏ Perform self-diagnosis. Enter checks for detected items. AT-8 2
, AT-9 0 .
❏ AT - 9 4 , "
DTC U1000 CAN COMMUNICATION LINE" .
❏ AT - 9 7 , "
DTC P0705 PARK/NEUTRAL POSITION (PNP) SWITCH" .
❏ AT-102, "
DTC P0710 A/T FLUID TEMPERATURE SENSOR CIRCUIT" .
❏ AT-107, "
DTC P0720 VEHICLE SPEED SENSOR·A/T (REVOLUTION SENSOR)" .
❏ AT - 11 3 , "
DTC P0725 ENGINE SPEED SIGNAL" .
❏ AT - 11 7 , "
DTC P0731 A/T 1ST GEAR FUNCTION"
❏ AT-121, "DTC P0732 A/T 2ND GEAR FUNCTION" .
❏ AT-124, "
DTC P0733 A/T 3RD GEAR FUNCTION" .
❏ AT-128, "
DTC P0734 A/T 4TH GEAR FUNCTION" .
❏ AT-134, "
DTC P0740 TORQUE CONVERTER CLUTCH SOLENOID VALVE" .
❏ AT-139, "
DTC P0744 A/T TCC S/V FUNCTION (LOCK-UP)" .
❏ AT-145, "
DTC P0745 LINE PRESSURE SOLENOID VALVE" .
❏ AT-151, "
DTC P0750 SHIFT SOLENOID VALVE A" .
❏ AT-156, "
DTC P0755 SHIFT SOLENOID VALVE B" .
❏ AT-161, "
DTC P1760 OVERRUN CLUTCH SOLENOID VALVE" .
❏ AT-166, "
DTC VEHICLE SPEED SENSOR MTR" .
❏ AT-170, "
DTC BATT/FLUID TEMP SEN (A/T FLUID TEMP SENSOR CIRCUIT AND TCM
POWER SOURCE)" .
❏ AT-176, "
DTC TURBINE REVOLUTION SENSOR" .
❏ AT-182, "
CONTROL UNIT (RAM), CONTROL UNIT (ROM)" .
❏ AT-183, "
MAIN POWER SUPPLY AND GROUND CIRCUIT" .
5.❏ For self-diagnosis NG items, inspect each component. Repair or replace the damaged parts.AT-8 2
,
AT-9 1
6.❏ Perform “Road Test”.AT-5 8
7.❏ Perform the Diagnostic Procedures for all remaining items marked NG. Repair or replace the damaged parts.
Refer to the Symptom Chart when you perform the procedures. (The chart also shows some other possible
symptoms and the component inspection orders.)AT-6 8
8.❏ Erase DTC from TCM and ECM memories.AT-8 3,
AT-9 3