TOYOTA SUPRA 1995 Service Repair Manual

SPEED SENSOR SIGNAL CHECK
1. Turn the ignition switch OFF
2. Using SST, connect terminals Ts and E1 of DLC1.
SST 09843±18020
3. Start the engine.
4. Check that the ABS warning light blinks.
HINT:
wIf the ABS warning light does not blink, inspect the ABS
warning light circuit (See page BR±107).
wIf the ABS warning light is always on, inspect and repair
the IG1 terminal of lateral acceleration sensor.
5. Drive the vehicle faster than 45 km/h (28 mph) for several
seconds.
6. Stop the vehicle.
7. Using SST, connect terminals Tc and E1 of DLC1.
SST 09843±18020
8. Read the number of blinks of the ABS warning light.
HINT: See the list of diagnostic trouble codes shown on the
next page.
If every sensor is normal, a normal code is output (A cycle of
0.25 sec. ON and 0.25 sec. OFF is repeated).
If 2 or more malfunctions are indicated at the same time, the
lowest numbered code will be displayed first.
9. After doing the check, disconnect terminals Ts and E1, Tc and
E1 of DLC1, and turn ignition switch OFF. BR±62
± BRAKE SYSTEMANTI±LOCK BRAKE SYSTEM (ABS)

ECU DATA MONITOR USING TOYOTA
HAND±HELD TESTER
1. Hook up the TOYOTA hand±held tester to the DLC2.
2. Monitor the ECU data by following the prompts on the tester
screen.
HINT: TOYOTA hand±held tester has a ºSnapshotº function
which records the monitored data.
Please refer to the TOYOTA hand±held tester operator's
manual for further details.
Diagnostic Trouble Code of Speed Sensor Check Function
 Code No. Diagnosis Trouble Area
 
 71
 
 Low output voltage of right front speed sensor
 
 

Right front speed sensor

Sensor installation
 
 72
 
 Low output voltage of left front speed sensor
 
 

Left front speed sensor

Sensor installation
 
 73
 
 Low output voltage of right rear speed sensor
 
 

Right rear speed sensor

Sensor installation
 
 74
 
 Low output voltage of left rear speed sensor
 
 

Left rear speed sensor

Sensor installation
 
 75
 
 
Abnormal change in output voltage of right front speed
sensor 
 
Right front speed sensor rotor
 
 76
 
 
Abnormal change in output voltage of left front speed
sensor 
 
Left front speed sensor rotor
 
 77
 
 
Abnormal change in output voltage of right rear speed
sensor 
 
Right rear speed sensor rotor
 
 78
 
 
Abnormal change in output voltage of left rear speed
sensor 
 
Left rear speed sensor rotor
± BRAKE SYSTEMANTI±LOCK BRAKE SYSTEM (ABS)BR±63

PROBLEM SYMPTOMS CHART
If a normal code is displayed during the diagnostic trouble code check but the problem still occurs, check the
circuits for each problem symptom in the order given in the table below and proceed to the relevant troubleshoot-
ing page.
 
 Symptoms
 
 Inspection Circuit
 
 See page
 
 
 
 
 
 
 
 
 
ABS does not
operate.
 
 
 
 
 
 
 
 
 
Only when 1. ~ 4. are all normal and the problem is still occurring,
replace the ABS (& TRAC) ECU.
1. Check the diagnostic trouble code, reconfirming that the normal
code is output.
2. IG power source circuit.
3. Speed sensor circuit.
4. Check the ABS actuator with a checker.
If abnormal, check the hydraulic circuit for leakage (See page
BR±115). 
 
 
 
 
 
 
 
 
BR±54
BR±92
BR±88
BR±44
 
 
 
 
 
 
 
 
ABS does not
operate efficiently
 
 
 
 
 
 
 
 
Only when 1. ~ 4. Are all normal and the problem is still occurring,
replace the ABS (& TRAC) ECU.
1. Check the diagnostic trouble code, reconfirming that the normal
code is output.
2. Speed sensor circuit.
3. Stop light switch circuit.
4. Check the ABS actuator with a checker.
If abnormal, check the hydraulic circuit for leakage (See page
BR±115). 
 
 
 
 
 
 
 
BR±54
BR±88
BR±105
BR±44
 
 
 
ABS warning
light abnormal
 
 
 
1. ABS warning light circuit.
2. ABS (& TRAC) ECU.
 
 
 
BR±107
 
 
 
 
Diagnostic trouble
code check cannot
be performed
 
 
 
 
Only when 1 and 2 are all normal and the problem is still occurring,
replace the ABS (& TRAC) ECU.
1. ABS warning light circuit.
2. Tc terminal circuit. 
 
 
 
BR±107
BR±112
 
 
 
 
Speed sensor signal
check cannot be
performed
 
 
 
 
1. Ts terminal circuit.
2. ABS (& TRAC) ECU.
 
 
 
 
BR±114
BR±64± BRAKE SYSTEMANTI±LOCK BRAKE SYSTEM (ABS)

CIRCUIT INSPECTION
DTC 11 12 ABS Solenoid Relay Circuit
CIRCUIT DESCRIPTION
This relay supplies power to each ABS solenoid. After the ignition switch is turned ON, if the initial check is OK,
the relay goes on.
 
 DTC No.
 
 Diagnostic Trouble Code Detecting Condition
 
 Trouble area
 
 
 
 
 
11
 
 
 
 
 
Conditions (1) and (2) continue for 0.2 sec.
or more:
(1) ABS solenoid relay terminal (SR)
voltage: Battery positive voltage
(2) Solenoid relay monitor terminal (AST)
voltage: O V 
 
 
 
 

ABS solenoid relay

Open or short in ABS solenoid relay circuit

ECU
 
 
 
 
 
12
 
 
 
 
 
Conditions (1) and (2) continue for 0.2 sec.
or more:
(1) ABS solenoid relay terminal (SR)
voltage: O V
(2) Solenoid relay monitor terminal (AST)
voltage: Battery positive voltage 
 
 
 
 

ABS solenoid relay

B+ short in ABS solenoid relay circuit

ECU
Fail safe function: If trouble occurs in the solenoid relay circuit, the ECU cuts off current to the solenoid relay
and prohibits ABS control.
± BRAKE SYSTEMANTI±LOCK BRAKE SYSTEM (ABS)BR±65

BR±66± BRAKE SYSTEMANTI±LOCK BRAKE SYSTEM (ABS)

Check voltage between terminals (A9) 2 and (A9) 6 of ABS solenoid relay
connector.
Disconnect the ABS solenoid relay connector.
Measure voltage between terminals (A9) 2 and
(A9) 6 of ABS solenoid relay harness side connec-
tor.
Voltage: 10 Ð 14 V
Check and repair harness or connector.
Repair or replace harness or ABS actuator.
Check continuity between terminal (A9) 5 OF ABS solenoid relay con-
nector and terminal (A19) 18 of ABS ECU.
Disconnect the connectors from ABS actuator.
Check continuity between terminal (A9) 5 of ABS
solenoid relay connector and terminal (A19) 18 of
ABS ECU.
Continuity.
There is a resistance of 4 ~ 6
between terminals
(A6) 4 and (A7) 2 of ABS actuator.
INSPECTION PROCEDURE (w/o TRAC)
± BRAKE SYSTEMANTI±LOCK BRAKE SYSTEM (ABS)BR±67

Check ABS solenoid relay.
Check for open and short in harness and connector between ABS sole-
noid relay and ABS ECU (See page IN±30).
Replace ABS control relay.
Repair or replace harness or connector.
Check continuity between each terminal of ABS
solenoid relay shown below.
(1) Apply battery voltage between terminals
(A9) 1 and (A8) 3.
(2) Check continuity between each terminal of
ABS solenoid relay shown below.
Terminals
Terminals
Terminals
1 and
5 and
2 and
Continuity
Continuity (Reference
value 80
)
Open
Terminals
Terminals
5 and
2 andContinuity
Open
 
 
 
If the same code is still output after the diagnostic trouble code is deleted, check the contact condi-
tion of each connection.
If the connections are normal, the ECU may be defective.
BR±68± BRAKE SYSTEMANTI±LOCK BRAKE SYSTEM (ABS)

Check voltage between terminals 1 and 2 of R/B No. 5 (for ABS solenoid
relay).
Check continuity between terminal 3 of R/B No.5 (for ABS solenoid
relay) and terminal (A20) 21 of ABS & TRAC ECU.
Check and repair harness or connector.
Repair or replace harness or ABS connector.
Remove ABS solenoid relay from R/B No. 5.
Measure voltage between terminals 1 and 2 of R/B
No. 5 (for ABS solenoid relay).
Voltage: 10 Ð 14 V
Check continuity between terminal 3 of R/B No.5
(for ABS solenoid relay) and terminal (A20) 21 OF
ABS & TRAC ECU.
Continuity
HINT: There is a resistance of 4 ~ 6
between terminals
(A6) 4 and (A7) 2 of ABS actuator.
INSPECTION PROCEDURE (w/ TRAC)
± BRAKE SYSTEMANTI±LOCK BRAKE SYSTEM (ABS)BR±69

Replace ABS solenoid relay.
Repair or replace harness or connector.
Check ABS solenoid relay.
Remove solenoid relay from R/B No. 5.
Check continuity between each terminal of ABS
solenoid relay shown below.
1. Apply battery voltage between terminals 4
and 6.
2. Check continuity between each terminal of
ABS solenoid relay shown below.
Check for open and short in harness and connector between ABS solenoid
relay and ABS & TRAC ECU (See page IN±30).
Terminals 1 and 3
Continuity
Continuity
(Reference value 80
)
Open
Terminals 2 and 3
Terminals 4 and 6
Terminals 2 and 3
Terminals 1 and 3Continuity
Open
 
 
 
If the same code is still output after the diagnostic trouble code is deleted, check the contact condi-
tion of each connection.
If the connections are normal, the ECU may be defective.
BR±70± BRAKE SYSTEMANTI±LOCK BRAKE SYSTEM (ABS)

EFEF
DTC 13 14 ABS Motor Relay Circuit
CIRCUIT DESCRIPTION
The ABS motor relay supplies power to the ABS pump motor. While the ABS is activated, the ECU switches
the motor relay ON and operates the ABS pump motor.
 DTC No. Diagnostic Trouble Code Detecting Condition Trouble area
 
 
 
 
 
 
13
 
 
 
 
 
 
Conditions (1) and (2) continue for 0.2 sec.
or more:
(1) ABS motor relay terminal (MR)
voltage: Battery positive voltage
(2) Motor relay monitor terminal (MT)
voltage: O V 
 
 
 
 
 

ABS motor relay

Open or short in ABS motor relay circuit

ECU
 
 
 
 
 
14
 
 
 
 
 
Conditions (1) and (2) continue for 4 sec. or
more:
(1) ABS motor relay terminal (MR)
voltage: O V
(2) Motor relay monitor terminal (MT)
voltage: Battery positive voltage 
 
 
 
 

ABS motor relay

B+ short in ABS motor relay circuit

ECU
Fail safe function: If trouble occurs in the motor relay circuit, the ECU cuts off the current to the solenoid relay
and prohibits ABS control.
± BRAKE SYSTEMANTI±LOCK BRAKE SYSTEM (ABS)BR±71