Lexus GS300/400 (2000 year). Service manual - part 36

BE0GS–10

I01362

Defogger Wire

Ignition Switch

Defogger Switch

Defogger Switch

Mirror Assembly

 Mirror Defogger

LEXUS navigation
System

Passenger Side
Junction Block

 DEF M–Fuse

 MIR HTR Fuse

 Mirror Defogger Relay

Mirror Assembly

 Mirror Defogger

Passenger Cowl Side
Relay Block

 Defogger Relay

–

BODY ELECTRICAL

DEFOGGER SYSTEM

BE–107

2408

DEFOGGER SYSTEM

LOCATION

BE0GT–03

I04112

6

I04113

I04114

Wire Harness Side

Connector ”A”

Connector ”B”

I01200

2

1

3

5

2

5

1

3

BE–108

–

BODY ELECTRICAL

DEFOGGER SYSTEM

2409

INSPECTION

1.

INSPECT DEFOGGER TIMER OPERATION

(a)

Connect the positive (+) lead from the voltmeter to termi-
nal 6 of body ECU No.1 connector and negative (–) lead
to body ground.

(b)

When the switch is OFF, the voltage should be approx.
12V.

(c)

Turn the defogger switch ON and check that the indicator
lights up and that the voltage is less than 1 V.

(d)

After 15 minutes, check that the switch is OFF and the
voltage is approx. 12 V.

If operation is not as specified, replace the switch.

2.

INSPECT DEFOGGER SWITCH (in PANEL SWITCH)
CIRCUIT
Connector disconnected:

Disconnect the connector from the panel switch and inspect the
connector on wire harness side, as shown in the chart.

Tester connection

Condition

Specified condition

B10 – Ground

Constant

Continuity

A1 – Ground

Constant

Battery voltage

A2 – Ground

Ignition switch LOCK

No voltage

A2 – Ground

Ignition switch ACC or ON

Battery voltage

If the circuit is not as specified, replace the switch.

3.

INSPECT DEFOGGER RELAY CONTINUITY

Condition

Tester connection

Specified condition

Constant

1 – 2

Continuity

Apply B+ between

terminals 1 and 2.

3 – 5

Continuity

If continuity is not as specified, replace the relay.
4.

INSPECT DEFOGGER RELAY CIRCUIT
(See page 

DI–812

 and 

BE–21

)

I01200

2

1

3

5

2

5

1

3

I01291

Tester Probe

Tin Foil

Heat Wire

I01292

At Center

I01293

0 Volts

Broken
Wire

Several
Volts

Battery
side

Ground side

Foil strip



–

BODY ELECTRICAL

DEFOGGER SYSTEM

BE–109

2410

5.

INSPECT MIRROR DEFOGGER RELAY CONTINUITY

Condition

Tester connection

Specified condition

Constant

1 – 2

Continuity

Apply B+ between

terminals 1 and 2.

3 – 5

Continuity

If continuity is not as specified, replace the relay.
6.

INSPECT MIRROR DEFOGGER RELAY CIRCUIT
(See page 

BE–21

)

7.

INSPECT DEFOGGER WIRE

NOTICE:

When cleaning the glass, use a soft, dry cloth, and wipe the

glass in the direction of the wire. Take care not to damage

the wires.

Do not use detergents or glass cleaners with abrasive in-

gredients.

When measuring voltage, wrap a piece of tin foil around the

tip of the negative probe and press the foil against the wire

with your finger, as shown.

(a)

Turn the ignition switch ON.

(b)

Turn the defogger switch ON.

(c)

Inspect the voltage at the center of each heat wire, as
shown.

Voltage

Criteria

Approx. 5V

Okay (No break in wire)

Approx. 10V or 0V

Broken wire

HINT:
If there is approximately 10 V, the wire is broken between the
center of the wire and the positive (+) end. If there is no voltage,
the wire is broken between the center of the wire and ground.
(d)

Place the voltmeter positive (+) lead against the defogger
wire on the battery side.

(e)

Place the voltmeter negative (–) lead with the foil strip
against the wire on the ground side.

(f)

Slide the positive (+) lead from battery to ground side.

(g)

The point where the voltmeter deflects from several V to
zero V is the place where the defogger wire is broken.

HINT:
If the heat wire is not broken, the voltmeter indicates 0 V at the
positive (+) end of the heat wire but gradually increases to about
12 V as the meter probe moves to the other end.

I01294

Repair Point

Broken
Wire

Marking Tape

I01295

I04115

7

8

I04269

12

13

BE–110

–

BODY ELECTRICAL

DEFOGGER SYSTEM

2411

8.

IF NECESSARY, REPAIR DEFOGGER WIRE

(a)

Clean the broken wire tips with grease, wax and silicone
remover.

(b)

Place the masking tape along both sides of the wire for
repair.

(c)

Thoroughly mix the repair agent (Dupont paste No.
4817).

(d)

Using a fine tip brush, apply a small amount of the agent
to the wire.

(e)

After a few minutes, remove the masking tape.

(f)

Do not repair the defogger wire for at least 24 hours.

9.

w/ Mirror heater (w/o Driving  position memory):
INSPECT MIRROR DEFOGGER OPERATION

(a)

Connect the positive (+) lead from the battery to terminal
7 and the negative (–) lead to terminal 8.

(b)

Check that the mirror becomes warm.

HINT:
It will take a short time for the mirror to become warm.

10.

w/ Mirror heater (w/  Driving  position memory):
INSPECT MIRROR DEFOGGER OPERATION

(a)

Connect the positive (+) lead from the battery to terminal
12 and the negative (–) lead to terminal 13.

(b)

Check that the mirror becomes warm.

HINT:
It will take a short time for the mirror to become warm.