1995 TOYOTA SUPRA ignition

INSPECTION PROCEDURE
Check battery positive voltage.
Voltage: 10 ± 14 V
Check and repair the charging system.
Remove TRAC ECU with connectors still
connected.
Turn ignition switch ON.
Measure voltage between terminals IG1 and
GND of TRAC ECU connector.
Voltage: 10 ± 14 V
Check voltage between terminals IG1 and GND of TRAC ECU connector.
Check and replace TRAC ECU.
Measure resistance between terminal GND of
TRAC ECU connector and body ground.
Resistance: 1
or less
Check continuity between terminal GND of TRAC ECU connector and
body ground.
Repair or replace harness or connector.
± BRAKE SYSTEMTRACTION CONTROL SYSTEM (TRAC)BR±143

Check voltage between terminal BRFA of TRAC ECU and body ground.
Remove TRAC ECU with connectors still con-
nected.
Turn ignition switch ON.
Measure voltage between terminal BRFA of TRAC
ECU and body ground.
Voltage: About 6 V (Pulse)
Check and replace TRAC ECU.
Check voltage between terminal BRFA of TRAC ECU and body ground with
TRAC ECU connector disconnected.
Disconnect TRAC ECU connector.
Measure voltage between terminal BRFA of TRAC
ECU connector and body ground.
HINT: Measure voltage within 8 seconds from the time
TRAC ECU connector is disconnected.
Voltage: See step 1.
Check and replace TRAC ECU.
Repair or replace harness or connector.
Check and replace ABS & TRAC ECU.
Check for open and short in harness and connector between ABS & TRAC
ECU and TRAC ECU (See page IN±30).
BR±146± BRAKE SYSTEMTRACTION CONTROL SYSTEM (TRAC)

(See page IN±30).
Check voltage between terminal NEO of TRAC ECU and body ground.
Remove TRAC ECU with connectors still con-
nected.
Repair or replace harness or connector.
Check and replace TRAC ECU or ECM.
Check for open and short in harness and connector between terminal NEO
of TRAC ECU and terminal NEO of ECM (See page IN±30).
Turn ignition switch ON.
Measure voltage between terminal NEO of TRAC
ECU and body ground for the engine conditions
below
If the same code is still output after the diagnostic code is deleted, check the contact condition of each
connection.
Engine condition
OFF (IG ON)
ON (Idling)
Voltage
4 ± 6 V or Below 1 V
2 ± 3 V (Pulse)
INSPECTION PROCEDURE
BR±148± BRAKE SYSTEMTRACTION CONTROL SYSTEM (TRAC)

INSPECTION PROCEDURE
HINT: The main throttle position sensor signal is transmitted to the TRAC ECU from ECM, so if an error occurs
at the engine side, the TRAC ECU also detects it.
If diagnostic trouble code No.41 is being output for the engine troubleshoot the engine first.
Remove TRAC ECU with connectors still con-
nected.
Disconnect the vacuum hose from the throttle
opener, and apply the vacuum to the throttle open-
er.
Is diagnostic trouble code output for the engine?
Turn ignition switch ON.
Measure voltage between terminal IDL1 of TRAC ECU
and body ground, when the main throttle valve is fully clo-
sed and fully open.
Main throttle valve position
Fully closed
Check voltage between terminal IDL1 of TRAC ECU and body ground.
Fully open
Voltage
Below 1.0 V
10 ± 14 V
Do diagnostic trouble code check on page EG±491.
Repair circuit indicated by the code output.
BR±150± BRAKE SYSTEMTRACTION CONTROL SYSTEM (TRAC)

INSPECTION PROCEDURE
HINT: The sub±throttle position sensor signal is transmitted to the TRAC ECU from ECM, so if an error occurs
at the engine side, the TRAC ECU also detects it.
If diagnostic trouble code No. 47 is being output for the engine, troubleshoot the engine first.
Check voltage between terminal IDL2 of TRAC ECU and body ground.
Remove TRAC ECU with connectors still con-
nected.
Remove intake air duct.
Disconnect step motor connector.
Repair circuit indicated by the code output.
Do diagnostic trouble code check on page EG±491.
Is diagnostic trouble code output for the engine?
Turn ignition switch ON.
Measure voltage between terminal IDL2 of TRAC ECU
and body ground, when the sub±throttle valve is fully
closed and fully open.
Go to step 6.
Engine condition
Sub±throttle valve position
Fully open
Voltage
Below 1.0 V
10 ± 14 V
Fully closed
± BRAKE SYSTEMTRACTION CONTROL SYSTEM (TRAC)BR±153

INSPECTION PROCEDURE
(See page IN±30).
Check for open and short n harness and connector between terminals
EFI+, EFI±, TRAC+ and TRC± of ECU and ECM (See page IN±30).
Check and replace TRAC ECU.
Check and replace TRAC ECU.
Repair or replace harness or connector.
Check and replace ABS & TRAC ECU.
Check voltage between terminals ABSO, BRC, BRP of TRAC ECU and
body ground with TRAC ECU connector disconnected.
Check for open and short in harness and connector between ABS & TRAC
ECU and TRAC ECU (See page IN±30).
Remove TRAC ECU with connectors still con-
nected.
Measure voltage between terminals ABSO, BRC,
BRP of TRAC ECU and body ground when ignition
switch is turned ON.
Voltage:
ABSO, BRC: 6 Ð 14 V
BRP: About 7 V (Pulse)
Disconnect TRAC ECU connector.
Measure voltage between terminals ABSO, BRC,
BRP of TRAC ECU and body ground when ignition
switch is turned ON.
Voltage: See step 1. BR±158
± BRAKE SYSTEMTRACTION CONTROL SYSTEM (TRAC)

(See page IN±30).
Check voltage between terminals Tc and E1 of DLC2 or DLC1.
Turn ignition switch ON
Measure voltage between terminals Tc and E1 of DLC2
or DLC1.
Voltage: 10 Ð 14 V
Proceed to next circuit inspection shown on
problem symptoms chart (See page BR±133).
Repair or replace harness or connector.
Check and replace TRAC ECU.
Check for open and short in harness and connector of symptoms con-
nected to Tc terminal (See page IN±30).
INSPECTION PROCEDURE
BR±164± BRAKE SYSTEMTRACTION CONTROL SYSTEM (TRAC)

EQUIPMENT
 Battery specific gravity gauge Except maintenance±free battery
 Torque wrench 
 Vernier calipers Rotor (Slip ring)
ON±VEHICLE INSPECTION
1. CHECK BATTERY ELECTROYTE LEVEL AND VOLTAGE
(a) Check the electrolyte quantity of each cell.
Maintenance±Free Battery:
If under the lower level, replace the battery (or add distilled
water if possible.). Need to check the charging system.
Except Maintenance±Free Battery:
If under the lower level, add distilled water.
(b) Except Maintenance±Free Battery:
Check the specific gravity of each cell.
Standard specific gravity:
1.27±1.29 at 205C (685F)
If the specific gravity is less than specification, charge the
battery.
(c) Maintenance±Free Battery:
Measure the battery voltage between the negative (±) and
positive (+) terminals of the battery.
Standard voltage:
12.7±12.9 V at 205C (685F)
HINT:
wBefore measuring the voltage, turn the ignition switch
OFF and turn off the electrical systems (headlight,
blower motor, rear defogger etc.) for 60 seconds to
remove the surface charge.
wIf the vehicle has been running, wait 5 minutes or more
after the vehicle stops before measuring the battery
voltage.
If the voltage is less than specification, charge the battery.
HINT: Check the indicator as shown in the illustration.
± CHARGING SYSTEMPREPARATIONCH±3