Lexus SC300 / Lexus SC400. Service manual - part 242

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BRAKE SYSTEM

TRACTION CONTROL SYSTEM (TRAC)

BR–219

WIRING DIAGRAM

DTC

61

ABS & TRAC ECU Communication Circuit
Malfunction

CIRCUIT DESCRIPTION

DTC No.

DTC Detecting Condition

Trouble Area

61

Malfunction in ABS & TRAC ECU communication cir-

cuit.

Open or short in ABSO, BRC, BRP circuit

ABS & TRAC ECU

TRAC ECU

DIAGNOSTIC CHART

DIAGNOSTIC CHART

BR–220

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BRAKE SYSTEM

TRACTION CONTROL SYSTEM (TRAC)

OK

NG

NG

OK

OK

NG

INSPECTION PROCEDURE

1

Check voltage between terminals ABSO, BRC, BRP of TRAC ECU and body ground.

C

OK

Hint

P

Remove TRAC ECU with connectors still connected.

Measure voltage between terminals ABSO, BRC, BRP
of TRAC ECU and body ground when ignition switch is
turned ON.

Voltage:

ABSO, BRC: 6 – 14 V

BRP: About 7 V (Pulse)\

(Reference)

Check and replace TRAC ECU.

2

Check voltage between terminals ABSO, BRC, BRP or TRAC ECU and body ground with TRAC
ECU connector is disconnected.

C

OK

Hint

P

Disconnect TRAC ECU connector.

Measure voltage between terminals ABSO, BRC, BRP
or TRAC ECU connector and body ground when ignition
switch is turned ON.

Voltage:

See step 1.

Check and replace TRAC ECU.

3

Check for open and short in harness and connector between ABS & TRAC ECU and TRAC ECU
(See page 

IN–33

).

Repair or replace harness or connector.

Check and replace ABS & TRAC ECU.

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BRAKE SYSTEM

TRACTION CONTROL SYSTEM (TRAC)

BR–221

TRAC OFF Indicator, TRAC Cut Switch Circuit

CIRCUIT DESCRIPTION

This is the TRAC control main switch. When the TRAC cut switch is pushed on, TRAC control goes off and
the TRAC OFF indicator lights up. This indicator is also used for warnings when the trouble occurs.

DIAGNOSTIC CHART

DIAGNOSTIC CHART

BR–222

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BRAKE SYSTEM

TRACTION CONTROL SYSTEM (TRAC)