1991 LEXUS SC300 Service Repair Manual

Page 1097 of 4087

LEXUS SC300 1991  Service Repair Manual 
OKNG
OKNG
INSPECTION PROCEDURES
1Check operation of TRAC pump & motor.
C
OK
P
Notice
Disconnect TRAC pump & motor connector.
Connect  positive  lead to terminal 3 or TRAC pump &
motor connector and

Page 1098 of 4087

LEXUS SC300 1991  Service Repair Manual 
OKNG
NGOK
OKNG
3Check harness and connector between ABS & TRAC ECU and TRAC pump & motor (Se\
e page
IN±33).
Repair or replace harness or connector.
4Check voltage between terminals PR and E2 of ABS

Page 1099 of 4087

LEXUS SC300 1991  Service Repair Manual 
BR±228
WIRING DIAGRAM
DTC54Excessive Operation of TRAC Pump Motor
CIRCUIT DESCRIPTION
DTC No.DTC Detecting ConditionTrouble Area
54
TRAC motor relay ON is output continuously10 times
at intervals of

Page 1100 of 4087

LEXUS SC300 1991  Service Repair Manual 
NGOK
OKNG
INSPECTION PROCEDURES
1Check voltage between terminals PR and E21 of ABS & TRAC ECU connector.
C
OK
P1. Remove ABS & TRAC ECU with connectors stillconnected.
2. Operate the engine for about

Page 1101 of 4087

LEXUS SC300 1991  Service Repair Manual 
WIRING DIAGRAM
DTC55Brake Fluid Level Warning Switch Circuit
CIRCUIT DESCRIPTION
The brake fluid level warning switch sends the appropriate signal to the EC\
U when the brake fluid level drops.
DTC N

Page 1102 of 4087

LEXUS SC300 1991  Service Repair Manual 
OKNG
OKNG
OKNG
INSPECTION PROCEDURE
1Check brake fluid level.
Check the amount of fluid in the bake reservoir.C
Check and repair brake fluid leakage and add fluid.
2Check brake fluid level warning sw

Page 1103 of 4087

LEXUS SC300 1991  Service Repair Manual 
DTC56, 57Pressure Sensor Circuit
CIRCUIT DESCRIPTION
The pressure sensor detects the TRAC accumulator hydraulic pressure and if \
it is low, it sends signals to the
ECU to operate the pump. If the pr

Page 1104 of 4087

LEXUS SC300 1991  Service Repair Manual 
WIRING DIAGRAM
DIAGNOSTIC CHARTDIAGNOSTIC CHART
±
BRAKE SYSTEM ANTI±LOCK BRAKE SYSTEM (ABS)BR±135 
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