4F-16 ANTILOCK BRAKE SYSTEM
Description
lCheck terminals for open or short.
(When connector is removed)
lReplace the hydraulic modulator.
lCheck each valve by using SCANNER's solenoid valve
overriding function.
lCheck connection of connector and terminals in the
ECU hydraulic modulator.
lCheck terminals for open or short.
(When connector is removed)
lReplace the hydraulic modulator
lCheck solenoid internal resistance of the prime(ASV)
valve and pilot valve(USV) : 8.04 - 9.04 W
lCheck each valve by using SCANNER's solenoid valve
overriding function.
lCheck connection of connector and terminals in the
ECU and hydraulic modulator.
lCheck terminals for open or short.
(When connector is removed)
lReplace the hydraulic modulator
lCheck solenoid internal resistance of the prime(ASV)
valve and pilot valve(USV) : 8.04 - 9.04 W
lCheck each valve by using SCANNER's solenoid valve
overriding function.
lCheck connection of connector and terminals in the
ECU and hydraulic modulator.
lCheck terminals for open or short.
(When connector is removed)
lReplace the hydraulic modulator
lCheck each valve by using SCANNER's pump motor
overriding function.
lCheck resistance between pump motor ground ter-
minal and battery negative terminal : total resistance
should be less than 15 mW
lCheck body ground location.
lCheck relay supply voltage : IGN on : 11 - 14 V
lRelay coil internal resistance : 70 - 80 W
lReplace the hydraulic modulator
lCheck by using SCANNER's stop lamp switch diag-
nosing function from sensor value output function.
lCheck connection of ECU connector side stop lamp
switch terminal.
lCheck resistance of the stop lamp, switch.
- Each end resistance value of the switch Application
Rear / Right OUTLET Valve
Function and Response of The
Valve
Function and Response of The
Valve
Motor Relay / Circulation Pump
Stop Lamp Switch
Defect Code
20
21
22
24
27
ANTILOCK BRAKE SYSTEM 4F-17
Application
Power Voltage
Residual Temperature
Measurement (ABD only)
Acceleration Sensor Signal (wire)Defect Code
28
29
42Description
when switch knob (planger) is pressed by 3mm : ¥
- Each ends resistance value of the switch when
switch knob(plunger) is not pressed :
less than 200 mW
lWhen brake is applied :
ECU (ABS:No.14, ABD:No.48) terminal 11 - 14 V
or VBattery.
When brake is released :
ECU (ABS:No.14, ABD:No.48) terminal 0 V
lCheck battery voltage.
lResistance between ECU (ABD:No.28 & 29,
ABS:No.19) pins and battery negative terminal :
less than 20 mW
lResistance between ECU No.1 (ABS:NO.15) pin and
ignition terminal : less than 60 mW
lCheck that normal voltage is applied to ECU
(ABD:No.1, ABS:No.15) pin when ignition switch is
turned to "ON" or "OFF".
lCheck ABS fuses of 15A and 80A.
lReplace the ECU.
lCheck wire (ECU No.50) for open or loose contact.
lCheck connection between connectors.
lCheck relevant wires for open or short.
(When connector is removed)
lCheck voltage between ECU side ground (ABD:No.1,
ABS:No.15 pin) and acceleration sensor side ground
(ABD:No.1, ABS:No.15 pin / ECU side ABD:No.39,
ABS:No.30 pin)
(When connector is installed and power is applied)
- Voltage : less than 0.25 V
lCheck voltage among related terminals.
(When connector is installed and power is applied)
- Voltage between ECU (ABD:No.43, ABS:No.28 pin
and ABD:No.39, ABS:No.30 pin)
: 4.75 - 5.25 V
- Signal voltage between ECU (ABD:No.51,
ABS:No.10) pin and (ABD:No.39, ABS:No.30) pin
: 1.95 V - 3.45 V
(Measure it by laying acceleration sensor horizon-
tally and without external force)
4F-18 ANTILOCK BRAKE SYSTEM
ApplicationDefect CodeDescription
lCheck connection between connectors.
lCheck relevant wires for open or short.
(When connector is removed)
lCheck and replace the acceleration sensor.
lReplace the ECU.
lCheck voltage between ECU side ground (ABD:No.1,
ABS:No.15 pin) and acceleration sensor side ground
(ABD:No.1, ABS:No.15 pin / ECU side ABD:No.39,
ABS:No.30 pin)
(When connector is installed and power is applied)
- Voltage : less than 0.25 V
lCheck voltage among related terminals.
(When connector is installed and power is applied)
- Voltage between ECU (ABD:No.51, ABS:No.10
pin and ABD:No39, ABS:No.30) pin
: 4.75 - 5.25 V
- Signal voltage between ECU (ABD:No.51,
ABS:No.10 pin and ABD:No39, ABS:No.30) pin
: 1.95 V - 3.45 V
(Measure it by laying acceleration sensor horizon
tally and without external force) 43Acceleration Sensor Signal (Signal)
ANTILOCK BRAKE SYSTEM 4F-19
MAINTENANCE AND REPAIR
ON-VEHICLE SERVICE
WHEEL SPEED SENSOR
1 Bolt
2 Front Wheel Speed Sensor
3 Knuckle4 Bolt
5 Rear Wheel Speed Sensor
6 Rear Axle
5A-22 AUTOMATIC TRANSMISSION
CONTROL SYSTEMS
GENERAL
There are two control systems associated with the transmission. The electronic control system monitors vehicle
parameters and adjusts the transmission performance. The hydraulic control system implements the electronic control
system commands.
ELECTRONIC CONTROL SYSTEM
The electronic control system is comprised of sensors, a TCU and seven solenoids. The TCU reads the inputs, and
under software control activates the outputs according to values stored in read only memory (ROM).
The TCU controls the hydraulic control system. This control is via the hydraulic valve body, which contains seven
electro-magnetic solenoids. Six of the seven solenoids are used to control the line pressure, operate the shift valves
and the torque converter lock-up clutch, and to turn on and off the two regulator valves (The two regulator valves
control the shift feel.).
The seventh solenoid is the proportional or variable pressure solenoid (VPS) which works with the two regulator
valves to control shift feel.
Figure 3.1 details a typical TCU control system schematic.
The individual component locations, operation and specifications which make up the electronic control subsystem
are covered in this section.
Figure 3.1 - Typical TCU Control System Schematic
5A-24 AUTOMATIC TRANSMISSION
Transmission Control Unit(TCU)
The TCU is an in-vehicle micro-processor based transmission management system. It is usually mounted in the
vehicle cabin, under the instrument panel, under the seat, behind the side kick panels or under the floor in the
footwell on the passenger side. Different control units are supplied for different vehicle applications.
The TCU contains:
lProcessing logic circuits which include a central microcontroller and a back-up memory system.
lInput circuits.
lOutput circuits which control external devices such as the variable pressure solenoid (VPS), on/off solenoid
drivers, a diagnostics output and the driving mode indicator light.
The various items which make up the TCU are discussed below.
Processing Logic
Shift schedule and calibration information is stored in an erasable programmable read only memory (EEPROM).
Throttle input calibration constants and the diagnostics information are stored in electrically erasable programmable
read only memory (EEPROM) that retains the memory even when power to the TCU is disconnected.
In operation the software continuously monitors the input values and uses these, via the shift schedule, to determine
the required gear state, At the same time it monitors, via the solenoid outputs, the current gear state. Whenever the
input conditions change such that the required gear state is different to the current gear state, the TCU initiates a
gear shift to bring the two states back into line.
Once the TCU has determined the type of gear shift required the software accesses the shift logic, estimates the
engine torque output, adjusts the variable pressure solenoid ramp pressure then executes the shift.
The TCU continuously monitors every input and output circuit for short or open circuits and operating range. When
a failure or abnormal operation is detected the TCU records the condition code in the diagnostics memory and
implements a limp mode, The actual limp mode used depends upon the failure detected with the object to maintain
maximum driveability without damaging the transmission. In general input failures are handled by providing a default
value. Output failures, which are capable of damaging the transmission, result in full limp mode giving only third or
fourth gear and reverse. For further details of limp modes and memory retention refer to the Diagnostic Section.
The TCU is designed to operate at ambient temperatures between -40 and 85°C . It is also protected against
electrical noise and voltage spikes, however all the usual precautions should be observed, for example when arc
welding or jump starting.
TCU Inputs
To function correctly, the TCU requires engine speed, road speed, transmission sump temperature, throttle position
and gear position inputs to determine the variable pressure solenoid current ramp and on/off solenoid states. This
ensures the correct gear selection and shift feel for all driving conditions.
The inputs required by the TCU are as follows:
lEngine Speed
The engine speed signal is derived from the tachometer signal line, a dedicated sensor or a Controlled Area
Network (CAN).
lRoad Speed
4WD (Diesel) - The shaft speed signal is derived from the speedo sensor located on the transfer case. This signal
is transmitted directly to the TCU.
4WD (Gasoline) - The speedo sensor sends the shaft speed signal to the engine control module (ECM). The
information is then transferred to the TCU via the CAN.
lTransmission Sump Temperature
The transmission sump temperature sensor is a thermistor located in the solenoid wiring loom within the transmission.
This sensor is a typical NTC resistor with low temperatures producing a high resistance and high temperatures
AUTOMATIC TRANSMISSION 5A-25
producing a low resistance.
Temperature/Resistance characteristics and location within the solenoid wiring loom are given in tables 3-1 and 3-
2, and figures 3.2 and 3.3.
If the transmission sump temperature exceeds 135°C, the TCU will impose converter lock-up at lower vehicle
speeds and in some vehicles flashes the mode indicator lamp. This results in maximum oil flow through the
external oil cooler and eliminates slippage in the torque converter. Both these actions combine to reduce the oil
temperature in the transmission.
Connects To
Solenoid 1
Solenoid 2
Solenoid 3
Solenoid 4
Solenoid 5
Solenoid 6
Solenoid 7
Solenoid 5
Temp Sensor
Temp SensorWire Color
Red
Blue
Yellow
Orange
Green
Violet
Brown
Green
White
WhitePin No.
1
2
3
4
5
6
7
8
9
10
Table 3.2 - Pin No. Codes for Temperature Sensor Location In Solenoid Loom
Figure 3.3 - Temperature Sensor Location in Solenoid Loom
5A-26 AUTOMATIC TRANSMISSION
Inhibitor
Switch Throttle Position Sensor
The throttle position sensor(TPS) is a resistance potentiometer
mounted on the throttle body of the engine.
It transmits a signal to the TCU proportional to the throttle plate
opening.
The potentiometer is connected to the TCU by three wires:
5 volts positive supply, earth and variable wiper voltage.
Throttle voltage adjustments are as follows:
lClosed throttle voltage is 0.2V to 1.0V.
lWide open throttle voltage is 3V -4.7V.
These measurements are taken between pins 29 and 27 of
the TCU.
Maintaining good shift feel through the transmission life span
is dependant on having an accurate measure of
the engine throttle position. To achieve this the TCU
continuously monitors the maximum and minimum throttle
potentiometer voltages and, if a change occurs, stores the new
voltage values.
However these limits will be lost and will require relearning
should a new TCU be installed, or the throttle calibration data
is cleared by the execution of a particular sequence, This last
instance depends on the installation, and reference should be
made to the Diagnostics Section of this manual. The relearning
will happen automaticallyNotice
Above figure of T.P.S. is for the diesel engine
which is installed on the injection pump.
Gear Position Sensor
The gear position sensor is incorporated in the inhibitor switch
mounted on the side of the transmission case.
(Refer to figure 3.5.) The gear position sensor is a multi-function
switch providing three functions:
lInhibit starting of the vehicle when the shift lever is in a
position other than Park or Neutral
lIlluminate the reversing lamps when Reverse is
selected indicate to the TCU which lever position has
been selected by way of a varying resistance (Refer to
table 3.3.)
Figure 3.5 - Inhibitor Switch