Lexus SC300 / Lexus SC400. Manual — part 241

OK

NG

10

Check sub–throttle position sensor (See page EG–609 or

EG–389

).

Adjust or replace sub–throttle position sensor (See page

EG–333

or

EG–205

).

Check and replace ECM.

–

BRAKE SYSTEM

TRACTION CONTROL SYSTEM (TRAC)

BR–215

IN–29

).

WIRING DIAGRAM

DTC

49

Engine Communication Circuit

CIRCUIT DESCRIPTION

This circuit is used to send ignition timing retard request signals from the TRAC ECU to the ECM in order to retard
the engine ignition timing.

DTC No.

DTC Detecting Condition

Trouble Area

49

TR2 output voltage differs from TR2 monitorvoltage in

TRAC ECU.

Open or short in TR2 circuit

ECM

TRAC ECU

DIAGNOSTIC CHART

DIAGNOSTIC CHART

BR–216

–

BRAKE SYSTEM

TRACTION CONTROL SYSTEM (TRAC)

NG

OK

OK

NG

INSPECTION PROCEDURE

1

Check voltage between terminal TR2 of TRAC ECU and body ground.

C

OK

Hint

P

1.

Disconnect TRAC ECU connector.

2.

Turn ignition switch on.

Measure voltage between terminal TR2 of TRAC ECU
and body ground.

Voltage:

8 – 14 V

Check and replace TRAC ECU.

2

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

IN–29

).

Repair or replace harness or connector.

Check and replace ECM.

–

BRAKE SYSTEM

TRACTION CONTROL SYSTEM (TRAC)

BR–217

TR–11

WIRING DIAGRAM

DTC

51

Engine Malfunction Detection Circuit

CIRCUIT DESCRIPTION

If trouble (trouble which causes the malfunction indicator light to light up) occurs in the engine control system,
this circuit senses the trouble and prohibits TRAC control.

DTC No.

DTC Detecting Condition

Trouble Area

51

Either of the following (1) and (2) continues formore

than 1 sec.:

(1) Engine speed: 500 RPM or more

(2) Voltage of TRAC ECU terminal TR5: 1 V or less

Short in TR5 circuit

ECM

TRAC ECU

DIAGNOSTIC CHART

DIAGNOSTIC CHART

BR–218

–

BRAKE SYSTEM

TRACTION CONTROL SYSTEM (TRAC)