A/T CONTROL SYSTEM
AT-33
< SERVICE INFORMATION >
D
E
F
G
H
I
J
K
L
MA
B
AT
N
O
P
OVERRUN CLUTCH OPERATING CONDITIONS
OVERRUN CLUTCH SOLENOID VALVE CONTROL
The overrun clutch solenoid valve is operated by an ON-OFF signal
transmitted by the TCM to provide overrun clutch control (engine
brake control).
When this solenoid valve is “ON”, the pilot pressure drain port
closes. When it is “OFF”, the drain port opens.
During the solenoid valve “ON” pilot pressure is applied to the end
face of the overrun clutch control valve.
OVERRUN CLUTCH CONTROL VALVE OPERATION
When the solenoid valve is “ON”, pilot pressure is applied to the
overrun clutch control valve. This pushes up the overrun clutch con-
trol valve. The line pressure is then shut off so that the clutch does
not engage. Only in “1” position, however, 1 range pressure is
applied to overrun clutch control valve, resulting in valve moving
downward and clutch engaged.
When the solenoid valve is “OFF”, pilot pressure is not generated. At
this point, the overrun clutch control valve moves downward by
spring force. As a result, overrun clutch operation pressure is pro-
vided by the overrun clutch reducing valve. At overrun clutch reduc-
ing valve in “D” position, the hydraulic pressure is reduced to a level
that balances the spring force. This is sent to overrun clutch control
valve and becomes the operating pressure of overrun clutch which is
engaged at all times. In “2” position and “1” position, overrun clutch
reducing valve is pushed down by 2 range pressure. Line pressure is
directly sent to overrun clutch control valve and becomes the operat-
ing pressure of overrun clutch which is engaged at all times.
SCIA7186E
SAT015J
SCIA7172E
AT-34
< SERVICE INFORMATION >
A/T CONTROL SYSTEM
Control Valve
INFOID:0000000001703170
FUNCTION OF CONTROL VALVES
Centrifugal Cancel MechanismINFOID:0000000001703171
FUNCTION
The centrifugal cancel mechanism is a mechanism to cancel the centrifugal hydraulic pressure instead of the
conventional check balls. It cancels the centrifugal hydraulic pressure which is generated as high clutch drum
rotates, and it allows for preventing high clutch from dragging and for providing stable high clutch piston press-
ing force in all revolution speeds.
STRUCTURE/OPERATION
Valve name Function
Pressure regulator valve, plug and sleeve
plugRegulates oil discharged from the oil pump to provide optimum line pressure for all driving
conditions.
Pressure modifier valve and sleeve Used as a signal supplementary valve to the pressure regulator valve. Regulates pres-
sure-modifier pressure (signal pressure) which controls optimum line pressure for all driv-
ing conditions.
Pilot valve Regulates line pressure to maintain a constant pilot pressure level which controls lock-up
mechanism, overrun clutch, shift timing.
Accumulator control valve Regulates accumulator back-pressure to pressure suited to driving conditions.
Manual valve Directs line pressure to oil circuits corresponding to select positions.
Hydraulic pressure drains when the shift lever is in Neutral.
Shift valve A Simultaneously switches three oil circuits using output pressure of shift solenoid valve A
to meet driving conditions (vehicle speed, throttle opening, etc.).
Provides automatic downshifting and upshifting (1st → 2nd → 3rd → 4th gears/4th → 3rd
→ 2nd → 1st gears) in combination with shift valve B.
Shift valve B Simultaneously switches two oil circuits using output pressure of shift solenoid valve B in
relation to driving conditions (vehicle speed, throttle opening, etc.).
Provides automatic downshifting and upshifting (1st → 2nd → 3rd → 4th gears/4th → 3rd
→ 2nd → 1st gears) in combination with shift valve A.
Overrun clutch control valve Switches hydraulic circuits to prevent engagement of the overrun clutch simultaneously
with application of the brake band in D
4. (Interlocking occurs if the overrun clutch engages
during D
4.)
1st reducing valve Reduces low & reverse brake pressure to dampen engine-brake shock when downshift-
ing from the 1st position 1
2 to 11.
Overrun clutch reducing valve Reduces oil pressure directed to the overrun clutch and prevents engine-brake shock.
In the 1st and 2nd positions, line pressure acts on the overrun clutch reducing valve to
increase the pressure-regulating point, with resultant engine brake capability.
Torque converter relief valve Prevents an excessive rise in torque converter pressure.
Torque converter clutch control valve, plug
and sleeveActivates or inactivates the lock-up function.
Also provides smooth lock-up through transient application and release of the lock-up
system.
1-2 accumulator valve and piston Lessens the shock find when the 2nd gear band servo contracts, and provides smooth
shifting.
3-2 timing valve Switches the pace that oil pressure is released depending on vehicle speed; maximizes
the high clutch release timing, and allows for soft downshifting.
Shuttle valve Determines if the overrun clutch solenoid valve should control the 3-2 timing valve or the
overrun clutch control valve and switches between the two.
Cooler check valve At low speeds and with a small load when a little heat is generated, saves the volume of
cooler flow, and stores the oil pressure for lock-up.
AT-36
< SERVICE INFORMATION >
ON BOARD DIAGNOSTIC (OBD) SYSTEM
ON BOARD DIAGNOSTIC (OBD) SYSTEM
IntroductionINFOID:0000000001703172
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-73, "
CONSULT-III Function (A/T)" .
OBD-II Function for A/T SystemINFOID:0000000001703173
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-IIINFOID:0000000001703174
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)INFOID:0000000001703175
HOW TO READ DTC AND 1ST TRIP DTC
DTC and 1st trip DTC can be read by the following methods.
( with CONSULT-III or GST) CONSULT-III or GST (Generic Scan Tool) Examples: P0705, P0720 etc.
These DTC are prescribed by SAE J2012.
(CONSULT-III 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-III can identify them as shown below, therefore, CONSULT-III (if available) is recom-
mended.
DTC or 1st trip DTC of a malfunction is displayed in SELF-DIAGNOSTIC RESULTS mode for “ENGINE” with
CONSULT-III. Time data indicates how many times the vehicle was driven after the last detection of a DTC.
If the DTC is being detected currently, the time data will be “0”.
If a 1st trip DTC is stored in the ECM, the time data will be “1t”.
Freeze Frame Data and 1st Trip Freeze Frame Data
The ECM has a memory function, which stores the driving condition such as fuel system status, calculated
load value, engine coolant temperature, short term fuel trim, long term fuel trim, engine speed and vehicle
speed at the moment the ECM detects a malfunction.
ON BOARD DIAGNOSTIC (OBD) SYSTEM
AT-37
< SERVICE INFORMATION >
D
E
F
G
H
I
J
K
L
MA
B
AT
N
O
P
Data which are stored in the ECM memory, along with the 1st trip DTC, are called 1st trip freeze frame data,
and the data, stored together with the DTC data, are called freeze frame data and displayed on CONSULT-III
or GST. The 1st trip freeze frame data can only be displayed on the CONSULT-III screen, not on the GST. For
detail, refer to EC-109, "
CONSULT-II Function (ENGINE)" .
Only one set of freeze frame data (either 1st trip freeze frame data of freeze frame data) can be stored in the
ECM. 1st trip freeze frame data is stored in the ECM memory along with the 1st trip DTC. There is no priority
for 1st trip freeze frame data and it is updated each time a different 1st trip DTC is detected. However, once
freeze frame data (2nd trip detection/MIL on) is stored in the ECM memory, 1st trip freeze frame data is no
longer stored. Remember, only one set of freeze frame data can be stored in the ECM. The ECM has the fol-
lowing priorities to update the data.
Both 1st trip freeze frame data and freeze frame data (along with the DTC) are cleared when the ECM mem-
ory is erased.
HOW TO ERASE DTC
The diagnostic trouble code can be erased by CONSULT-III, GST or ECM DIAGNOSTIC TEST MODE as
described following.
•If the battery cable is disconnected, the diagnostic trouble code will be cleared within 24 hours.
•When you erase the DTC, using CONSULT-III or GST is easier and quicker than switching the mode
selector on the ECM.
The following emission-related diagnostic information is cleared from the ECM memory when erasing DTC
related to OBD-II. For details, refer to EC-47, "
Emission-related Diagnostic Information" .
•Diagnostic trouble codes (DTC)
•1st trip diagnostic trouble codes (1st trip DTC)
•Freeze frame data
•1st trip freeze frame data
•System readiness test (SRT) codes
•Test values
HOW TO ERASE DTC (WITH CONSULT-III)
•If a DTC is displayed for both ECM and TCM, it is necessary to be erased for both ECM and TCM.
1. If the ignition switch stays ON after repair work, be sure to turn ignition switch OFF once. Wait at least 10
seconds and then turn it ON (engine stopped) again.
2. Turn CONSULT-III “ON” and touch “A/T”.
3. Touch “SELF-DIAG RESULTS”.
4. Touch “ERASE”. (The DTC in the TCM will be erased.) Then touch “BACK” twice.
5. Touch “ENGINE”.
6. Touch “SELF-DIAG RESULTS”.
7. Touch “ERASE”. (The DTC in the ECM will be erased.)
HOW TO ERASE DTC (WITH GST)
1. If the ignition switch stays ON after repair work, be sure to turn ignition switch OFF once. Wait at least 10
seconds and then turn it ON (engine stopped) again.
2. Perform “TCM SELF-DIAGNOSTIC PROCEDURE (No Tools)”. Refer to AT-78, "
Diagnosis Procedure
without CONSULT-III" . (The engine warm-up step can be skipped when performing the diagnosis only to
erase the DTC.)
3. Select Mode 4 with Generic Scan Tool (GST). For details, refer to EC-119, "
Generic Scan Tool (GST)
Function" .
HOW TO ERASE DTC (NO TOOLS)
The OD OFF indicator lamp is located on the combination meter.
Priority Items
1
Freeze frame dataMisfire — DTC: P0300 - P0306
Fuel Injection System Function — DTC: P0171, P0172, P0174, P0175
2 Except the above items (Includes A/T related items)
3 1st trip freeze frame data
AT-38
< SERVICE INFORMATION >
ON BOARD DIAGNOSTIC (OBD) SYSTEM
1. If the ignition switch stays ON after repair work, be sure to turn ignition switch OFF once. Wait at least 10
seconds and then turn it ON (engine stopped) again.
2. Perform “TCM SELF-DIAGNOSTIC PROCEDURE (No Tools)”. Refer to AT-78, "
Diagnosis Procedure
without CONSULT-III" . (The engine warm-up step can be skipped when performing the diagnosis only to
erase the DTC.)
3. Perform “OBD-II SELF-DIAGNOSTIC PROCEDURE (No tools)”. Refer to EC-47, "
Emission-related Diag-
nostic Information" .
Malfunction Indicator Lamp (MIL)INFOID:0000000001703176
DESCRIPTION
The MIL is located on the instrument panel.
1. The MIL will light up when the ignition switch is turned ON with-
out the engine running. This is a bulb check.
• If the MIL does not light up, refer to DI-21
, or see EC-546 .
2. When the engine is started, the MIL should go off.
• If the MIL remains on, the on board diagnostic system has
detected an engine system malfunction.
SEF217U
AT-40
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
●: Solenoid ON
×: Solenoid OFF
–: Non-standard condition
Line Pressure Solenoid Valve
If non-standard solenoid signal is sent to TCM, line pressure solenoid valve is turned OFF to achieve maxi-
mum oil pressure.
Torque Converter Clutch Solenoid Valve
If non-standard solenoid signal is sent to TCM, torque converter clutch solenoid valve is turned OFF to release
lock-up.
Overrun Clutch Solenoid Valve
If non-standard solenoid signal is sent to TCM, overrun clutch solenoid valve is turned OFF to engage overrun
clutch. This will result in more effective engine brake during deceleration.
How to Perform Trouble Diagnosis for Quick and Accurate RepairINFOID:0000000001703179
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 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 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.
Shift positionNormalMalfunction in solenoid
valve AMalfunction in solenoid
valve BMalfunction in solenoid
valves A and B
A B Gear A B Gear A B Gear A B Gear
“D” position●●1st –●→×
3rd ●→×–
3rd ––
3rd ×●2nd –●→× ×–––
××3rd – x×–––
●×4th – x●→×–––
“2” position●●1st –●→×●→×–––
×●2nd –●→× ×–––
××3rd – x×–––
“1” position●●1st –●→×●→×–––
×●2nd –●→× ×–––
××3rd – x×–––
SAT631IA
TROUBLE DIAGNOSIS
AT-41
< SERVICE INFORMATION >
D
E
F
G
H
I
J
K
L
MA
B
AT
N
O
P
A visual check only, may not find the cause of the malfunctions. A
road test with CONSULT-III or a circuit tester connected should be
performed. Follow the "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 ("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.
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 symptoms
or conditions for a customer complaint.
Make good use of the two sheets provided, "Information from customer" and "Diagnostic Worksheet Chart" ,
to perform the best troubleshooting possible.
Work Flow Chart
SAT632I
SEF234G
TROUBLE DIAGNOSIS
AT-43
< SERVICE INFORMATION >
D
E
F
G
H
I
J
K
L
MA
B
AT
N
O
P Diagnostic Worksheet Chart
Customer name MR./MS Model & Year VIN
Trans. model Engine Mileage
Incident Date Manuf. Date In Service Date
Frequency❏ Continuous❏ Intermittent ( times a day)
Symptoms❏ Vehicle does not move. (❏ Any position❏ Particular position)
❏ No up-shift (❏ 1st → 2nd❏ 2nd → 3rd❏ 3rd → 4th)
❏ No down-shift (❏ 4th → 3rd❏ 3rd → 2nd❏ 2nd → 1st)
❏ Lock-up malfunction
❏ Shift point too high or too low.
❏ Shift shock or slip (❏ N → D❏ Lock-up❏ Any drive position)
❏ Noise or vibration
❏ No kick down
❏ No pattern select
❏ Others
()
Malfunction indicator lamp (MIL)❏ Continuously lit❏ Not lit
1.❏ Read the Fail-safe and listen to customer complaints.AT- 3 9,
"Information
from custom-
er"
2.❏ Check A/T fluidMA-22
❏ Leakage (Follow specified procedure)
❏ Fluid condition
❏ Fluid level
3.❏ Perform “STALL TEST” and “LINE PRESSURE TEST”.AT- 4 8
,
AT- 4 8
❏“STALL TEST”— Mark possible damaged components/others.
❏ Torque converter one-way clutch
❏ Reverse clutch
❏ Forward clutch
❏ Overrun clutch
❏ Forward one-way clutch❏ Low & reverse brake
❏ Low one-way clutch
❏ Engine
❏ Line pressure is low
❏ Clutches and brakes except high clutch and
brake band are OK
❏“LINE PRESSURE TEST”— Suspected parts: