Lexus SC300 / Lexus SC400. Manual - part 235

BR–120

WIRING DIAGRAM

DIAGNOSTIC CHART

DIAGNOSTIC CHART

–

BRAKE SYSTEM

TRACTION CONTROL SYSTEM (TRAC)

BR–191

IN–33

).

WIRING DIAGRAM

DTC

41

IG Power Source Circuit

CIRCUIT DESCRIPTION

This is the power source for the ECU and becomes power source for the CPU and actuators.

DTC No.

DTC Detecting Condition

Trouble Area

41

When either of the following (1) or (2) is detected:

(1) Voltage at ECU terminal IG is less than 9.5 V for

more than 10 sec. while engine speed is 500 rpm

or higher.

(2) Voltage at ECU terminal IG is more than 17 V for

more than 5 sec.

Battery

IC regulator

Open or short in power source circuit

ECU

Fail safe function: If trouble occurs in the power source circuit, the ECU prohibits TRAC control.

DIAGNOSTIC CHART

DIAGNOSTIC CHART

BR–192

–

BRAKE SYSTEM

TRACTION CONTROL SYSTEM (TRAC)

OK

NG

NG

OK

OK

NG

INSPECTION PROCEDURE

1

Check battery positive voltage.

Voltage:

10 – 14 V

C

OK

Check and repair the charging system.

2

Check voltage between terminals IG and GND of TRAC ECU connector.

C

OK

P

1.

Remove TRAC ECU with connectors still con-
nected.

2.

Turn ignition switch on.

Measure voltage between terminals IG and GND of
TRAC ECU connector.

Voltage:

10 – 14 V

Check and replace TRAC ECU.

3

Check continuity between terminals GND of TRAC ECU connector and body ground.

C

OK

Measure resistance between terminal GND or TRAC
ECU connector and body ground.

Resistance:

1 

 or less

Repair or replace harness or connector.

–

BRAKE SYSTEM

TRACTION CONTROL SYSTEM (TRAC)

BR–193

OK

NG

4

Check ECU–IG fuse.

C

OK

P

Remove ECU–IG fuse from J/B No. 1.

Check continuity of ECU–IG fuse.

Continuity

Check for short in all the harness and components con-
nected to ECU–IG fuse (See attached wiring diagram).

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

IN–33

).

BR–194

–

BRAKE SYSTEM

TRACTION CONTROL SYSTEM (TRAC)