Lexus SC300 / Lexus SC400. Service manual - part 236

–MEMO–

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BRAKE SYSTEM

TRACTION CONTROL SYSTEM (TRAC)

BR–195

WIRING DIAGRAM

DTC

43

ABS & TRAC ECU Malfunction

CIRCUIT DESCRIPTION

DTC No.

DTC Detecting Condition

Trouble Area

43

ABS control system or TRAC (BRAKE) control system

or communication circuit is abnormal.

ABS & TRAC ECU

Open or short in BRFA circuit

DIAGNOSTIC CHART

DIAGNOSTIC CHART

BR–196

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BRAKE SYSTEM

TRACTION CONTROL SYSTEM (TRAC)

NG

OK

NG

OK

OK

NG

INSPECTION PROCEDURE

1

Check voltage between terminal BRFA of TRAC ECU and body ground.

C

OK

P

1.

Remove TRAC ECU with connectors still con-
nected.

2.

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.

2

Check voltage between terminal BRFA of TRAC ECU and body ground with TRAC ECU connec-
tor is disconnected.

C

OK

Hint

P

Disconnect TRAC ECU connector.

Measure voltage between terminal BRFA of TRAC ECU
connector and body ground.

Measure voltage within 8 seconds from the time TRAC
ECU connector is disconnected.

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–197

WIRING DIAGRAM

DTC

44

NE Signal Circuit

CIRCUIT DESCRIPTION

The TRAC ECU receives engine speed signals (NE signals) from the ECM.

DTC No.

DTC Detecting Condition

Trouble Area

44

No signal is input to terminal NEO 0.24 sec. after trac-

tion control is initiated.

Open or short in NEO circuit

ECM

TRAC ECU

DIAGNOSTIC CHART

DIAGNOSTIC CHART

BR–198

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BRAKE SYSTEM

TRACTION CONTROL SYSTEM (TRAC)