Lexus SC300 / Lexus SC400. Manual — part 237

OK

NG

OK

NG

INSPECTION PROCEDURES

1

Check for open and short in harness and connector between terminal NEO of TRAC ECU and
terminal NEO of ECM (See page

IN–33

).

Repair or replace harness or connector.

2

Check voltage between terminal NEO 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 NEO of TRAC ECU
and body ground for the engine conditions below.

Check and replace TRAC ECU or ECM.

If the same code is still output after the diagnostic code is deleted, check the contact condition of each
connection.

–

BRAKE SYSTEM

TRACTION CONTROL SYSTEM (TRAC)

BR–199

DTC

45, 46 Main Throttle Position Sensor Circuit

CIRCUIT DESCRIPTION

This circuit is not directly related to the TRAC control, but as it has an influence on TRAC control when trouble
occurs in this circuit, it is used to switch off the TRAC system as a fail safe function.

DTC No.

DTC Detecting Condition

Trouble Area

45

Either of the following (1) and (2) continues for 0.12

sec.:

(1) IDL switch of main throttle position sensoris ON.

(2) Input voltage of TRAC ECU terminal VTH:1.45 V or

more.

Main throttle position sensor

Open in VTH circuit

Short in IDL1 circuit

ECM

TRAC ECU

46

Either of the following (1) or (2) continues for0.12 sec.:

(1) Input voltage of TRAC ECU terminal VTH:4.3 V or

more.

(2) Input voltage of TRAC ECU terminal VTHwhile

IDL1 switch is OFF: 0.2 V or less

Main throttle position sensor

Short in VTH circuit

ECM

TRAC ECU

BR–200

–

BRAKE SYSTEM

TRACTION CONTROL SYSTEM (TRAC)

EG–608

or

EG–388

).

EG–333

or

EG–205

).

EG–609

or

EG–389

).

EG–481

).

DIAGNOSTIC CHART

DIAGNOSTIC CHART

–

BRAKE SYSTEM

TRACTION CONTROL SYSTEM (TRAC)

BR–201

WIRING DIAGRAM

BR–202

–

BRAKE SYSTEM

TRACTION CONTROL SYSTEM (TRAC)