Service Manuals, User Guides, Schematic Diagrams or docs for : . Car Manuals Toyota Celica 1988-1989.1993-1994.2000 Approved Toyota Celica 1993 ANTI_LO2
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ANTI-LOCK BRAKE SYSTEM
1993 Toyota Celica
1993 BRAKES
Toyota Anti-Lock
Celica
DESCRIPTION
The Anti-Lock Brake System (ABS) consists of an ABS
Electronic Control Unit (ECU), control relay, actuator, deceleration
sensor (All-Trac), and 4 speed sensors. See Fig. 1.
An ABS indicator light is located on the instrument panel.
This light comes on for 3 seconds as a bulb test when ignition is
first turned on. A primary check is performed after each engine start,
and initial vehicle speed exceeds 4 MPH. If brake pedal is pressed
before vehicle exceeds 4 MPH, primary check will not occur until brake
pedal is released.
NOTE: For more information on brake system, see BRAKE SYSTEM
article in this section.
OPERATION
Under normal driving conditions, the ABS functions as a
standard brake system. With detection of wheel lock-up, short pedal
pulsations occurring in rapid succession will be felt in brake pedal.
Pedal pulsation will continue until there is no longer a need for ABS
function.
CAUTION: See ANTI-LOCK BRAKE SAFETY PRECAUTIONS in this article.
ANTI-LOCK BRAKE SAFETY PRECAUTIONS
* NEVER open a bleeder valve or loosen a hydraulic line while
ABS is pressurized
* NEVER disconnect or reconnect any electrical connectors while
ignition is on. Damage to ABS control unit may result.
* DO NOT attempt to bleed hydraulic system without first
referring to the appropriate article.
* Only use specially designed brake hoses/lines on ABS-equipped
vehicles.
* DO NOT tap on speed sensor components (sensor, sensor rings).
Speed rings must be pressed, NOT hammered into hubs. Striking
these components can cause demagnetization or a loss of
polarization, affecting the accuracy of the speed signal
returning to the ABS control unit.
* DO NOT mix tire sizes. Increasing the width, as long as tires
remain close to the original diameter, is acceptable. Rolling
diameter must be identical for all 4 tires. Some
manufacturers recommend tires of the same brand, style and
type. Failure to follow this precaution may cause inaccurate
wheel speed readings.
* DO NOT contaminate speed sensor components with grease. Only
use recommended anti-corrosion coating.
* When speed sensor components have been removed, ALWAYS check
sensor-to-ring air gaps when applicable. These specifications
can be found in each appropriate article.
* ONLY use recommended brake fluids. DO NOT use silicone brake
fluids in an ABS-equipped vehicle.
* When installing transmitting devices (CB's, telephones, etc.)
on ABS-equipped vehicles, DO NOT locate the antenna near the
ABS control unit (or any control unit).
* Disconnect all on-board computers, when using electric
welding equipment.
* DO NOT expose the ABS control unit to prolonged periods of
high heat (185 F/85 C for 2 hours is generally considered a
maximum limit).
Fig. 1: Locating ABS Components
Courtesy of Toyota Motor Sales, U.S.A., Inc.
BLEEDING BRAKE SYSTEM
CAUTION: Brake fluid will damage painted surfaces. If brake fluid gets
on a painted surface, wipe off immediately and clean with
alcohol. Use only DOT 3 brake fluid from a sealed container.
Do not mix brake fluid with any other type.
Brake bleeding procedure is same procedure used to bleed non-
ABS systems. If master cylinder was rebuilt or reservoir ran empty,
bleed master cylinder first. Bleed remaining wheels, starting with
brake having longest hydraulic line, working to brake with shortest
hydraulic line.
ADJUSTMENTS
MASTER CYLINDER PUSH ROD
1) Install Adjusting Gauge (09737-00010) onto master
cylinder, with master cylinder gasket in place. Lower gauge pin until
it just touches master cylinder piston. See Fig. 2 (STEP 1). Invert
gauge, then install onto power brake unit (STEP 2).
2) Measure clearance between brake unit push rod and head of
adjusting gauge. Clearance should be zero. If clearance is not zero,
adjust brake unit push rod length until push rod just touches head of
gauge pin.
Fig. 2: Adjusting Master Cylinder Push Rod
Courtesy of Toyota Motor Sales, U.S.A., Inc.
BRAKE PEDAL HEIGHT
1) Measure brake pedal height from face of brake pedal pad to
rib of floor panel. See Fig. 3. Brake pedal height should be 6.7-7.0"
(169-178 mm). To adjust brake pedal height, loosen stoplight switch
and lock nut on brake pedal push rod.
2) Adjust pedal height by rotating push rod. After adjusting
brake pedal height, tighten lock nut. Adjust stoplight switch. See
STOPLIGHT SWITCH. Check and adjust brake pedal free play. See BRAKE
PEDAL FREE PLAY.
Fig. 3: Measuring Brake Pedal Height & Free Play
Courtesy of Toyota Motor Sales, U.S.A., Inc.
BRAKE PEDAL FREE PLAY
1) Brake pedal free play is distance brake pedal travels
(with engine stopped) before encountering resistance. To measure brake
pedal free play, press brake pedal several times to exhaust vacuum
from power brake unit. Press brake pedal and measure travel until
initial resistance occurs.
2) Brake pedal free play should be 0.04-0.24" (1.0-6.0 mm).
If free play is not within specification, adjust by rotating push rod.
See Fig. 3. After adjusting brake pedal free play, check brake pedal
height. See BRAKE PEDAL HEIGHT.
BRAKE PEDAL RESERVE
Measure brake pedal reserve from face of brake pedal pad to
asphalt sheet under carpet, with engine running and force of 110 lbs.
(50 kg) applied to brake pedal. Minimum brake pedal reserve should be
3.54" (90.0 mm). If distance is less than specified, inspect brake
system.
STOPLIGHT SWITCH
Stoplight switch is located above brake pedal. See Fig. 3. To
adjust stoplight switch, loosen stoplight switch lock nuts and rotate
stoplight switch until clearance between pedal stop and threaded end
of switch is 0.02-0.09" (0.5-2.4 mm). Tighten lock nut. Check
stoplight operation.
PARKING BRAKE SHOES
Raise and support vehicle. Remove wheels. Temporarily install
lug nuts to hold brake rotor in place. Remove hole plug to gain access
to adjuster. Turn adjuster to expand shoes until brake rotor locks.
Back off adjuster 8 notches. Install hole plug.
PARKING BRAKE
NOTE: Service brake on rear drum brakes and parking brake shoe
clearance on rear disc brakes must be adjusted before
adjusting parking brake cable.
Parking brake lever stroke should be 4-7 notches (clicks)
with a pull force of 44 lbs. (20 kg). To adjust stroke, remove console
box. Loosen parking brake cable lock nut. Rotate adjuster nut until
parking brake lever travel is as specified. Tighten lock nut. Install
console box.
TROUBLE SHOOTING
ANTI-LOCK WARNING LIGHT
ABS Light Comes On
1) Unplug service connector. See Fig. 4. Connect jumper wire
between Data Link Connector (DLC) terminals Tc and E1. See Fig. 5.
Turn ignition on. If ABS light flashes codes, see DIAGNOSTIC CODES
under DIAGNOSIS & TESTING. If ABS light stays on constantly or flashes
4 times per second, go to next step.
Fig. 4: Locating Service Connector
Courtesy of Toyota Motor Sales, U.S.A., Inc.
Fig. 5: Locating Data Link Connector DLC
Courtesy of Toyota Motor Sales, U.S.A., Inc.
2) Inspect ABS ECU connector for secure attachment and
undamaged terminals. Repair connector as necessary. Turn ignition on.
Check for battery voltage between ABS ECU connector terminal IG1
(Black/Red wire) and ground. See Fig. 6 or 7. If battery voltage
exists, go to next step. If battery voltage does not exist, repair
faulty Black/Red wire.
3) Turn ignition off. Unplug ABS ECU connector. Turn ignition
on. If ABS light comes on, repair short circuit between 6-pin ABS
control relay connector terminal No. 4 (Green wire) and ABS ECU
connector terminal "W" (Gray wire). If ABS light does not come on,
temporarily substitute known good ABS ECU. Retest system.
Fig. 6: Identifying ABS System Connector Terminals (FWD)
Courtesy of Toyota Motor Sales, U.S.A., Inc.
Fig. 7: Identifying ABS System Connector Terminals (All-Trac)
Courtesy of Toyota Motor Sales, U.S.A., Inc.
ABS Light Does Not Come On For 3 Seconds After Ignition Is
Turned On
1) Unplug service connector. See Fig. 4. Connect service
connector terminal "W" on harness (female) side to ground. Turn
ignition on. If ABS light comes on, go to next step. If ABS light does
not come on, replace ABS bulb, or repair open circuit between ABS
light and service connector terminal "W". See Fig. 6 or 7.
2) Turn ignition off. Unplug ABS ECU connector and ABS
control relay connectors. Connect ABS ECU connector terminal "W" (Gray
wire) on wire harness side to ground. Turn ignition on. If ABS light
comes on, go to next step. If ABS light does not come on, repair open
circuit between ABS ECU connector terminal "W" (Gray wire) and ABS
light.
3) Turn ignition off. Unplug ABS control relay connector.
Check for continuity between 6-pin ABS control relay connector
terminals No. 4 and 5. Transpose ohmmeter leads. Again check for
continuity.
4) If continuity exists with ohmmeter connected only one way,
temporarily substitute known good ABS ECU, then retest system. If
continuity exists with ohmmeter connected both ways, or continuity
does not exist at all, see ABS CONTROL RELAY under COMPONENT TESTING.
5) If short in ABS control relay diode exists, a malfunction
at ABS ECU terminal "W" (Gray wire) will occur. When inspecting
terminal, reconnect ABS wiring. Unplug control relay connectors and
DLC. Turn ignition on. If ABS light comes on, ABS ECU terminal "W"
(Gray wire) is okay.
ABS Light Comes On Intermittently
Inspect for a short in wiring harness between DLC terminals
Tc and E1 or between terminals Ts and E1. See Fig. 5.
SYMPTOM DIAGNOSIS
Symptoms:
* Brakes Pull
* Braking Inefficient
* ABS Operates During Normal Braking
* ABS Operates Just Before Stopping During Normal Braking
* Brake Pedal Pulsates Abnormally With ABS Functioning
Diagnosis
1) Unplug service connector. See Fig. 4. Connect jumper wire
between DLC terminals Tc and E1. See Fig. 5. Turn ignition on. If ABS
light flashes 2 times per second, go to next step. If ABS light does
not flash 2 times per second, refer to DIAGNOSTIC CODES under
DIAGNOSIS & TESTING.
2) On FWD vehicles, go to next step. On All-Trac vehicles,
enter deceleration sensor diagnostics. See DECELERATION SENSOR
DIAGNOSTICS (ALL-TRAC) under DIAGNOSIS & TESTING. If deceleration
sensor operation is okay, go to next step. If deceleration sensor
operation is not as specified, inspect sensor for proper installation.
If sensor is installed properly, replace sensor.
3) Check actuator operation. See ACTUATOR CHECK under
DIAGNOSIS & TESTING. If actuator operation is okay, temporarily
substitute known good ECU. Retest system. See ABS ECU under REMOVAL &
INSTALLATION. If actuator operation is not as specified, replace
faulty actuator.
4) Enter speed sensor diagnostics. See SPEED SENSOR
DIAGNOSTICS under DIAGNOSIS & TESTING. If speed sensor signal level is
okay, go to next step. If speed sensor signal level is not okay,
inspect sensor and sensor rotor. Replace as necessary.
5) Inspect all speed sensors for proper installation, and
repair as necessary. Clean all foreign material and metal chips from
speed sensor tip.
6) Turn ignition off. Unplug ABS ECU connector. Ensure
continuity exists between each speed sensor connector and ABS ECU
connector. If continuity readings change when wiring harness is
twisted or moved, repair faulty wiring harness between speed sensor
and ABS ECU connector.
Symptom:
* ABS Works Inefficiently
Diagnosis
1) Unplug service connector. See Fig. 4. Connect jumper wire
between DLC terminals Tc and E1. See Fig. 5. Turn ignition on. If ABS
light flashes 2 times per second, go to next step. If ABS light does
not flash 2 times per second, refer to DIAGNOSTIC CODES under
DIAGNOSIS & TESTING.
2) Check for battery voltage between ABS ECU connector
terminal STP (Green/White wire) and ground when brake pedal is
pressed. If battery voltage does not exist, repair open circuit in
stoplight switch or wiring harness. Check actuator operation. See
ACTUATOR CHECK under DIAGNOSIS & TESTING.
DIAGNOSIS & TESTING
NOTE: DO NOT start engine when retrieving diagnostic codes.
RETRIEVING CODES
1) Ensure battery voltage is about 12 volts. Turn ignition
on. ABS light should come on, then go out after 3 seconds. If warning
light does not come on, check fuse, bulb, and wiring harness.
2) With ignition on, unplug DLC. See Fig. 4. Connect jumper
wire between DLC terminals Tc and E1. See Fig. 5. If a malfunction is
detected, 4 seconds will elapse, then ABS light will begin to flash a
2-digit code. First series of flashes indicates first digit of code.
After a 1.5-second pause, second series of flashes indicates second
digit of code.
3) If 2 or more codes are stored, there will be a 2.5-second
pause between each code. After all codes are displayed, a 4-second
pause will occur, then all codes will repeat. If ABS system is
functioning properly, ABS light will flash 2 times every second. For
code interpretation, see DIAGNOSTIC CODES.
4) After replacing or repairing malfunctioning components,
clear diagnostic codes. If a battery cable was disconnected during
repairs, all codes will be erased. If battery cable was not
disconnected during repairs, see CLEARING CODES.
DIAGNOSTIC CODES
Check suspect components in order given. Checks consist
mainly of a visual inspection and continuity tests.
Code 11
Open in solenoid relay circuit. Check actuator wiring
harness, ABS control relay (solenoid relay), solenoid relay wiring
harness, and solenoid relay connector. See ABS CONTROL RELAY under
COMPONENT TESTING.
Code 12
Short in solenoid relay circuit. Check actuator wiring
harness, ABS control relay (solenoid relay), solenoid relay wiring
harness, and solenoid relay connector. See ABS CONTROL RELAY under
COMPONENT TESTING.
Code 13
Open in pump motor relay circuit. Check actuator wiring
harness, ABS control relay (pump motor relay), pump motor relay wiring
harness, and pump motor relay connector. See ABS CONTROL RELAY under
COMPONENT TESTING.
Code 14
Short in pump motor relay circuit. Check actuator wiring
harness, ABS control relay (pump motor relay), pump motor relay wiring
harness, and pump motor relay connector. See ABS CONTROL RELAY under
COMPONENT TESTING.
Code 21
Open or short circuit in solenoid for right front wheel.
Check actuator solenoid, wiring harness, and connector. See ACTUATOR
CHECK under DIAGNOSIS & TESTING.
Code 22
Open or short circuit in solenoid for left front wheel. Check
actuator solenoid, wiring harness, and connector. See ACTUATOR CHECK
under DIAGNOSIS & TESTING.
Code 23
Open or short circuit in solenoid for right rear wheel. Check
actuator solenoid, wiring harness, and connector. See ACTUATOR CHECK
under DIAGNOSIS & TESTING.
Code 24
Open or short circuit in solenoid for left rear wheel. Check
actuator solenoid, wiring harness, and connector. See ACTUATOR CHECK
under DIAGNOSIS & TESTING.
Code 31
Malfunction of right front wheel speed sensor signal. Check
speed sensor, sensor rotor, wiring harness, and connector. See SPEED
SENSOR DIAGNOSTICS under DIAGNOSIS & TESTING.
Code 32
Malfunction of left front wheel speed sensor signal. Check
speed sensor, sensor rotor, wiring harness, and connector. See SPEED
SENSOR DIAGNOSTICS under DIAGNOSIS & TESTING.
Code 33
Malfunction of right rear wheel speed sensor signal. Check
speed sensor, sensor rotor, wiring harness, and connector. See SPEED
SENSOR DIAGNOSTICS under DIAGNOSIS & TESTING.
Code 34
Malfunction of left rear wheel speed sensor signal. Check
speed sensor, sensor rotor, wiring harness, and connector. See SPEED
SENSOR DIAGNOSTICS under DIAGNOSIS & TESTING.
Code 35
Open in left front or right rear wheel speed sensor circuit.
Check speed sensor, sensor rotor, wiring harness, and connector. See
SPEED SENSOR DIAGNOSTICS under DIAGNOSIS & TESTING.
Code 36
Open in right front or left rear wheel speed sensor circuit.
Check speed sensor, sensor rotor, wiring harness, and connector. See
SPEED SENSOR DIAGNOSTICS under DIAGNOSIS & TESTING.
Code 37 (FWD)
Wrong rear axle hubs on both sides. Check rear sensor rotors.
Code 41
Battery voltage is less than 9.5 volts or more than 16.2
volts. Check battery and voltage regulator.
Code 43 (All-Trac)
Deceleration sensor malfunction. Check deceleration sensor,
deceleration sensor installation, wiring harness, and connector. See
DECELERATION SENSOR DIAGNOSTICS (ALL-TRAC) under DIAGNOSIS & TESTING.
Code 44 (All-Trac)
Open or short circuit in deceleration sensor. Check
deceleration sensor, deceleration sensor installation, wiring harness,
and connector. See DECELERATION SENSOR DIAGNOSTICS (ALL-TRAC) under
DIAGNOSIS & TESTING.
Code 51
Actuator pump motor is locked or pump motor circuit open.
Check pump motor, ABS control relay (pump motor relay), vehicle
battery, actuator wiring harness, connectors, actuator pump motor
circuit, and actuator ground bolt. See ACTUATOR CHECK under DIAGNOSIS
& TESTING. See ABS CONTROL RELAY under COMPONENT TESTING.
ABS Light Always On
Malfunction of ABS ECU. Inspect ABS ECU connector for proper
installation and undamaged terminals. Repair as necessary. If
connector is okay, temporarily substitute known good ABS ECU. Retest
system.
CLEARING CODES
Turn ignition on. Connect jumper wire between DLC terminals
Tc and E1. See Fig. 5. With vehicle stopped, press brake pedal 8 or
more times within 3 seconds. Codes will be erased. Turn ignition on.
Verify ABS light goes out after 3 seconds. Verify ABS light flashes a
normal code. See RETRIEVING CODES under DIAGNOSIS & TESTING.
ACTUATOR CHECK
1) Turn ignition off. Unplug actuator and control relay
electrical connectors. See Fig. 6 or 7. Connect Test Harness (09990-
00200) and Actuator Checker (09990-00150) to vehicle according to
manufacturer's instructions.
2) Place Sheet "A" (09990-00163) onto actuator checker. Start
and idle engine. Set SELECTOR switch to FRONT RH position. Press and
hold MOTOR switch for a few seconds. Press and hold brake pedal.
NOTE: DO NOT press POWER switch for longer than 10 seconds.
3) Press POWER switch. When POWER switch is pressed, brake
pedal should not go down. Release POWER switch. Brake pedal should go
down. Press and hold MOTOR switch for a few seconds. Brake pedal
should return. Release MOTOR switch. Release brake pedal.
4) Press and hold MOTOR switch for a few seconds. Release
MOTOR switch. Press and hold brake pedal for about 15 seconds. As
brake pedal is held, press MOTOR switch for a few seconds. Brake pedal
should not pulsate.
5) Repeat steps 2) through 4) for FRONT LH, REAR RH, and REAR
LH by setting SELECTOR switch to appropriate positions. When checking
REAR LH position, press REAR LH switch instead of POWER switch.
6) After checking remaining wheels, press and hold MOTOR
switch for a few seconds. Remove test harnesses and actuator checker.
7) If any actuator solenoid does not operate as specified,
measure actuator solenoid resistance. Measure resistance of each
actuator solenoid between 6-pin connector terminal No. 4 (White wire)
and appropriate actuator solenoid connector. Resistance should be 1.2
ohms.
8) Replace actuator if resistance of any actuator solenoid is
not as specified. Reconnect wiring harnesses to actuator and control
relay. Clear diagnostic codes. See CLEARING CODES.
SPEED SENSOR DIAGNOSTICS
NOTE: While diagnosing speed sensors, brake system functions as a
conventional system.
1) Ensure battery voltage is about 12 volts. Turn ignition
on. ABS light should come on, then go out after about 3 seconds. If
ABS light does not come on, check fuse, bulb, and wiring harness.
2) Turn ignition off. DO NOT remove short pin from DLC.
Connect DLC terminals Ts and E1. See Fig. 5. Engage parking brake.
Start engine. Verify ABS light flashes 4 times per second.
3) Drive vehicle straight ahead at speed greater than 50 MPH.
Verify ABS light flashes while vehicle is traveling at less than 28
MPH. ABS light will stop flashing at more than 28 MPH, and will then
flash once at 50 MPH. If ABS light flashes as described, check is
complete. If ABS light does not flash as indicated, stop vehicle.
4) Connect jumper between DLC terminals Tc and E1. See
Fig. 5. If a malfunction is detected, 4 seconds will elapse, then ABS
light will begin to flash a 2-digit code. First series of flashes
indicates first digit of code. After a 1.5 second pause, second series
of flashes indicates second digit of code.
5) If 2 or more codes are stored, there will be a 2.5-second
pause between each code. After all codes are flashed, there will be a
4-second pause, then all codes will repeat.
6) Record diagnostic codes. Turn ignition off. Repair as
necessary. See SPEED SENSOR DIAGNOSTIC CODES. Remove jumper wire from
DLC. Clear diagnostic codes. See CLEARING CODES.
SPEED SENSOR DIAGNOSTIC CODES
Code 71
Low voltage of right front speed sensor signal. Check right
front speed sensor and sensor installation.
Code 72
Low voltage of left front speed sensor signal. Check left
front speed sensor and sensor installation.
Code 73
Low voltage of right rear speed sensor signal. Check right
rear speed sensor and sensor installation.
Code 74
Low voltage of left rear speed sensor signal. Check left rear
speed sensor and sensor installation.
Code 75
Abnormal signal from right front speed sensor. Check right
front sensor rotor.
Code 76
Abnormal signal from left front speed sensor. Check right
front sensor rotor.
Code 77
Abnormal signal from right rear speed sensor. Check right
rear sensor rotor.
Code 78
Abnormal signal from left rear speed sensor. Check left rear
sensor rotor.
ABS Light Blinks 4 Times A Second
All speed sensors and sensor rotors are normal.
DECELERATION SENSOR DIAGNOSTICS (ALL-TRAC)
NOTE: While diagnosing deceleration sensor, brake system functions
as a conventional system.
System Inspection
1) Ensure battery voltage is about 12 volts. Turn ignition
on. ABS light should come on, then go out after 3 seconds. If ABS
light does not come on, check fuse, bulb, and wiring harness.
2) Turn ignition off. Connect jumper wire between DLC
terminals E1 and Ts. See Fig. 5. Engage parking brake. Start engine.
DO NOT press brake pedal.
3) If ABS flashes 4 times per second, inspect sensor
detection point and sensor operation. If ABS light does not flash,
inspect parking brake switch, stoplight switch, DLC Ts terminal,
deceleration sensor installation, and ABS ECU.
Sensor Detection Point
1) Raise rear of vehicle 26-28", measured from bottom of rear
bumper to ground. Verify ABS light is off. Completely lower rear of
vehicle. As vehicle is lowered, ABS light will start flashing. Raise
front of vehicle 21-24", measured from lower body or spoiler edge of
vehicle to ground.
2) Verify ABS light is off. As vehicle is lowered, ABS light
will start flashing. If ABS light stays on steadily, inspect
deceleration sensor installation. If sensor installation is okay,
replace deceleration sensor.
Sensor Operation
1) Drive vehicle straight ahead at speed greater than 50 MPH.
Verify ABS light flashes while vehicle is traveling at less than 28
MPH. ABS light will stop flashing at more than 28 MPH, and then will
flash once at 50 MPH. If ABS light flashes as described, check is
complete. If ABS light does not flash as indicated, stop vehicle.
2) Connect jumper between DLC terminals Tc and E1 (do not
disconnect Ts and E1) of DLC. See Fig. 5. If a malfunction is
detected, 4 seconds will elapse, then ABS light will begin to flash a
2-digit code. First series of flashes indicates first digit of code.
After a 1.5-second pause, second series of flashes indicates second
digit of code.
3) If 2 or more codes are stored, there will be a 2.5-second
pause between each code. After all codes are flashed, there will be a
4-second pause, then all codes will repeat.
4) Record diagnostic codes. Turn ignition off. Repair as
necessary. See DIAGNOSTIC CODES. Remove jumper wires from DLC. Clear
diagnostic codes. See CLEARING CODES.
COMPONENT TESTING
ABS ECU Wiring Harness
1) Remove ABS ECU, leaving connectors attached. See ABS ECU
under REMOVAL & INSTALLATION. Backprobe each terminal to measure
voltage or resistance at each terminal, as specified in table. See
STEP 1
See Fig. 8 or 9 and 10. If circuit values are not as
specified, check and repair or replace indicated component.
2) Unplug ABS ECU connectors. Measure resistance on wire
harness side of ABS ECU connector terminals, as specified in table.
See STEP 2
See Fig. 8 or 10. If circuit values are not as specified,
check and repair or replace indicated component.
Fig. 8: Testing Specifications Table For ABS ECU Wiring Harness - FWD
Courtesy of Toyota Motor Sales, U.S.A., Inc.
Fig. 9: Testing Specs Table For ABS ECU Wir Harness All-Trac (1 Of 2)
Courtesy of Toyota Motor Sales, U.S.A., Inc.
Fig. 10: Testing Specs Table For ABS ECU Wir Harness All-Trac(2 Of 2)
Courtesy of Toyota Motor Sales, U.S.A., Inc.
ABS Control Relay
1) Remove ABS control relay. See Fig. 1. Using ohmmeter
capable of testing diodes, check for continuity between ABS control
relay connector terminals A3 and A4. See Fig. 11. Transpose ohmmeter
leads. Repeat measurement.
2) If continuity exists or circuit is open for both
measurements, actuator diode is defective. Repair or replace relay,
then go to next step. If continuity exists for only one measurement,
temporarily substitute known good ABS ECU. Retest system.
3) Continuity should exist between terminals A3 and A6,
between terminals A3 and A5, and between terminals A5 and A6.
4) Continuity should not exist between terminals A2 and A3,
or between terminals B1 and B2.
5) Using fused jumper wire, connect positive battery terminal
to terminal B3. Connect negative battery terminal to terminal B4.
Continuity should not exist between terminals B1 and B2.
6) Using fused jumper wire, connect positive battery terminal
to terminal B3. Connect negative battery terminal to terminal A1.
Continuity should exist between terminals A2 and A5. Continuity should
not exist between terminals A3 and A5. Replace relay if operation is
not as specified.
Fig. 11: Identifying ABS Control Relay Terminals
Courtesy of Toyota Motor Sales, U.S.A., Inc.
Front Speed Sensors
1) Remove harness connector clamp. Unplug connector from
front wheel speed sensor. Measure resistance between speed sensor
terminals. Resistance should be 800-1300 ohms.
2) Measure insulation resistance between each sensor terminal
and sensor body. Continuity should not exist. If resistance and
continuity are not as specified, replace speed sensor.
Rear Speed Sensors
1) Remove rear seat cushion. Unplug wheel speed sensor
connector. Measure resistance between speed sensor terminals. On All-
Trac models, resistance should be 800-1500 ohms. On FWD models,
resistance should be 1100-1700 ohms.
2) Measure insulation resistance between each sensor terminal
and sensor body. Continuity should not exist. If resistance and
continuity are not as specified, replace speed sensor.
Sensor Rotors
Visually inspect sensor rotor serrations for scratches,
cracks, missing teeth, or warping. Replace front drive shaft or rear
hub as necessary if rotor is damaged.
REMOVAL & INSTALLATION
WARNING: Hydraulic system may be under high pressure. Use caution when
opening hydraulic system.
ABS ECU
Removal & Installation
1) Turn ignition off. Disconnect negative battery cable. ABS
ECU is located on right side of luggage compartment (left side on
convertible models). Remove screws attaching ABS ECU to vehicle.
2) Remove wire harness from ECU bracket clamp. Unplug ABS ECU
connector. Remove ABS ECU from vehicle. To install, reverse removal
procedure.
ABS CONTROL RELAY
Removal & Installation
Remove connector from wire harness clamp. Remove relay bolt.
Remove relay from vehicle. See Fig. 1. To install, reverse removal
procedure.
ACTUATOR
Removal & Installation
Turn ignition off. Remove actuator cover. Unplug electrical
connectors. Remove cover bracket and bolt. Disconnect brake lines.
Remove actuator from bracket. To install, reverse removal procedure.
Bleed brake system. See BLEEDING BRAKE SYSTEM.
FRONT SENSOR ROTOR
Front speed sensor rotor is an integral part of outboard CV
joint. See appropriate DRIVE AXLES article in the POWERTRAIN section.
FRONT WHEEL SPEED SENSORS
See Fig. 12.
Fig. 12: Removing & Installing Front Speed Sensor
Courtesy of Toyota Motor Sales, U.S.A., Inc.
REAR SENSOR ROTOR (ALL TRAC)
Rear speed sensor rotor is an integral part of outboard CV
joint. See appropriate DRIVE AXLES article in the POWERTRAIN section.
REAR SENSOR ROTOR (FWD)
Removal & Installation
Rear speed sensor rotor is an integral part of rear hub.
Remove rear hub. See SUSPENSION - REAR article in the SUSPENSION
section.
REAR WHEEL SPEED SENSORS
See Fig. 13.
Fig. 13: Removing & Installing Rear Speed Sensor
Courtesy of Toyota Motor Sales, U.S.A., Inc.
OVERHAUL
DO NOT attempt to overhaul or disassemble actuator assembly.
If actuator is defective, replace entire assembly.
TORQUE SPECIFICATIONS
TORQUE SPECIFICATIONS TABLE
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