TOYOTA SUPRA 1995 Service Repair Manual

Check TRAC motor relay.
Remove TRAC solenoid relay from R/B No. 5.
Check continuity between each terminal of TRAC
solenoid relay shown below.
Terminals 1 and 2
Open
Continuity
(Reference value 62)Terminals 3 and 4
Terminals 1 and 2
Continuity
1. Apply battery voltage between terminals
3 and 4.
2. Check continuity between terminal shown
below.
Replace TRAC solenoid relay.
Repair or replace harness or connector.
Check for open and short in harness and connector between TRAC motor
relay and ABS & TRAC ECU (See page
IN±30).
If the same code is still output after the diagnostic trouble code is deleted, check the contact
condition of each connection.
If the connections are normal, the ECU may be defective. BR±82
± BRAKE SYSTEMANTI±LOCK BRAKE SYSTEM (ABS)

DTC 21 22 23 24 ABS Actuator Solenoid Circuit
CIRCUIT DESCRIPTION
This solenoid goes on when signals are received from the ECU and controls the fluid pressure acting on the
brake cylinders, thus controlling the braking force.
 DTC No. Diagnostic Trouble Code Detecting Condition Trouble area
 







21






 
Conditions (1) through (3) continue for 0.05
sec. or more:
(1) ABS solenoid relay terminal (SR)
voltage: Battery positive voltage
(2) Voltage of ABS (& TRAC) ECU terminal
AST: Battery positive voltage
(3) When power transistor of ECU is ON,
voltage of terminal SFR is 0 V or battery
positive voltage. 
 
 
 
 
 
 

ABS actuator

Open or short in SFR circuit.

ECU
 







22






 
Conditions (1) through (3) continue for 0.05
sec. or more:
(1) ABS solenoid relay terminal (SR)
voltage: Battery positive voltage
(2) Voltage of ABS (& TRAC) ECU terminal
AST: Battery positive voltage
(3) When power transistor of ECU is ON,
voltage of terminal SFL is 0 V or battery
positive voltage. 
 
 
 
 
 
 

ABS actuator

Open or short in SFL circuit.

ECU
 








23







 
Conditions (1) through (3) continue for 0.05
sec. or more:
(1) ABS solenoid relay terminal (SR)
voltage: Battery positive voltage
(2) Voltage of ABS (& TRAC) ECU terminal
AST: Battery positive voltage
(3) When power transistor of ECU is ON,
voltage of terminal SRR is 0 V or battery
positive voltage.
 
 
 
 
 
 
 
 

ABS actuator

Open or short in SRR circuit.

ECU
 







24






 
Conditions (1) through (3) continue for 0.05
sec. or more:
(1) ABS solenoid relay terminal (SR)
voltage: Battery positive voltage
(2) Voltage of ABS (& TRAC) ECU terminal
AST: Battery positive voltage
(3) When power transistor of ECU is ON,
voltage of terminal SRL is 0 V or battery
positive voltage. 
 
 
 
 
 
 

ABS actuator

Open or short in SRL circuit.

ECU
Fail safe function: If trouble occurs in the actuator solenoid circuit, the ECU cuts off current to the solenoid relay
and prohibits ABS control.
± BRAKE SYSTEMANTI±LOCK BRAKE SYSTEM (ABS)BR±83

BR±84± BRAKE SYSTEMANTI±LOCK BRAKE SYSTEM (ABS)

Check ABS actuator solenoid.
Check continuity between terminal (A6) 4 and (A7)
1, 3, 4, 6 of the ABS actuator connector.
Continuity
Replace ABS actuator.
Check for open and short in harness and connector between ABS (& TRAC)
ECU and actuator (See page
IN±30).
HINT: Resistance of each solenoid coil is 1.1
.
Repair or replace harness or connector.
If the same code is still output after the diagnostic trouble code is deleted, check the contact
condition of each connection.
If the connections are normal, the ECU may be defective.
± BRAKE SYSTEMANTI±LOCK BRAKE SYSTEM (ABS)BR±85

DTC 25 27 TRAC Actuator Solenoid Circuit
CIRCUIT DESCRIPTION
The TRAC actuator solenoid operates in accordance with signals from the ECU and raises the fluid pressure
in and releases it from the brake cylinders.
 DTC No. Diagnostic Trouble Code Detecting Condition Trouble area 
 
 
 
 
25
 
 
 
 
 
Conditions (1) and (2) continue for 0.05 sec.
or more:
(1) TRAC solenoid relay terminal (TSR)
voltage: Battery positive voltage
(2) Voltage oS & TRAC ECU terminal AB
SMC: 0 V
 
 
 
 
 

TRAC actuator

Open or short in SMC circuit

ECU
 
 
 
 
 
 
27
 
 
 
 
 
 
Conditions (1) and (2) continue for 0.05 sec.
or more:
(1) TRAC solenoid relay terminal (TSR)
voltage: Battery positive voltage
(2) Voltage of ABS & TRAC ECU terminal
SRC: 0V
 
 
 
 
 
 

TRAC actuator

Open or short in SRC circuit

ECU
Fail safe function: If trouble occurs in this solenoid circuit, the ECU cuts off current to the ABS and TRAC solenoid
relays and prohibits ABS and TRAC control.
BR±86± BRAKE SYSTEMANTI±LOCK BRAKE SYSTEM (ABS)

If the same code is still output after the diagnostic trouble code is deleted, check the contact
condition of each connection.
If the connections are normal, the ECU may be defective.
Check TRAC actuator solenoid.
Disconnect TRAC actuator connector.
Check continuity between each terminal of TRAC
solenoid relay shown below.
Open
Continuity
(Reference value  )Terminals 2 and 4
Terminals 1 and 2
Repair or replace harness or connector.
Check for short in harness and connector between SMC and SRC terminals
with TRAC actuator and ECU connectors are disconnected.
Terminals 1 and 3
Repair or replace harness or connector.
Replace TRAC actuator.
Check for open and short in harness and connector between solenoid relay
and ECU (See page
IN±30).
`
± BRAKE SYSTEMANTI±LOCK BRAKE SYSTEM (ABS)BR±87

CIRCUIT DESCRIPTION
The speed sensor detects the wheel speed and sends the ap-
propriate signals to the ECU. These signals are used to control
both the ABS and TRAC control systems. The front and rear ro-
tors each have 48 serrations. When the rotors rotate, the mag-
netic field emitted by the permanent magnet in the speed sensor
generates an AC voltage. Since the frequency of this AC volt-
age changes in the direct proportion to the speed of the rotor,
the frequency is used by the ECU to detect the speed of each
wheel.
31, 32
33, 34
35
36
Detection of any of conditions (1) through (3):
(1) At vehicle speed of 10 km/h (6 mph) or
more, pulses are not input for 5 sec.
(2) Momentary interruption of he vehicle
speed sensor signal occurs at least 7
times in the time between switching the
ignition switch ON and switching it OFF.
(3) Abnormal fluctuation of speed sensor sig±
nals with the vehicle speed 20 km/H (12
mph) or more.
Speed sensor signal is not input for about 1
sec. while the left front and right rear speed
sensor signals are being checked with the IG
switch ON.
Speed sensor signal is not input for about 1
sec. while the right front and left rear speed
sensor signals are being checked with the IG
switch ON.

Right front, left front, right rear and left rear
speed sensor.

Open or short in each speed sensor circuit.

ECU

Open in left front, right rear speed sensor
circuit.

ECU

Open in right front, left rear speed sensor
circuit.

ECU
HINT: DTC No.31 is for the right front speed sensor.
DTC No. 32 is for the left front speed sensor.
DTC No.33 is for the right rear speed sensor.
DTC No.34 is for the left rear speed sensor.
Fail safe function: If trouble occurs in the speed sensor circuit, the ECU cuts off current to the ABS
solenoid relay and prohibits ABS control.
DTC 31 32 33 34 35 36 Speed Sensor Circuit
BR±88± BRAKE SYSTEMANTI±LOCK BRAKE SYSTEM (ABS)

± BRAKE SYSTEMANTI±LOCK BRAKE SYSTEM (ABS)BR±89

Check speed sensor.
Replace speed sensor.
Repair or replace harness or connector.
Check for open and short in harness and connector between each speed sen-
sor and ECU (See page
IN±30).
NOTICE: Check the speed sensor signal last (See page BR±62).
Front
Rear
1. Remove front fender splash shield.
2. Disconnect speed sensor connector.
Measure resistance between terminals 1 and 2 of
speed sensor connector.
Resistance : 0.7 Ð 1.7 k
Measure resistance between terminals 1 and 2 of
speed sensor connector and body ground.
Resistance : 1 Mor higher
1. Remove rear set cushion, seat back and
quarter trim panel.
2. Disconnect speed sensor connector.
Measure resistance between terminals 1 and 2 of
speed sensor connector.
Resistance : 0.7 Ð 1.7 k
Measure resistance between terminals 1 and 2 of
speed sensor connector and body ground.
Resistance : 1 Mor higher BR±90
± BRAKE SYSTEMANTI±LOCK BRAKE SYSTEM (ABS)

Check sensor rotor and sensor installation.
Replace speed sensor or rotor.
Remove front speed sensor rotor (See page
SA±15).
Check sensor rotor serrations.
No scratches or missing teeth.
Check the front speed sensor installation.
The installation bolt is tightened properly.
Remove the drive shaft (See page BR±45).
Check sensor rotor serrations.
No scratches or missing teeth.
Check and replace ABS (& TRAC) ECU.
NOTICE: Check the speed sensor signal last (See page BR±62).
Check the rear speed sensor installation.
The installation bolt is tightened properly and
there is no clearance between the sensor and
rear axle carrier.
± BRAKE SYSTEMANTI±LOCK BRAKE SYSTEM (ABS)BR±91