Lexus RX300 (MCU15). Service manual - part 133

BE0UF–02

Z12091

Z06620

I01291

Tester Probe

Tin Foil

Heat Wire

I01292

At Center

–

BODY ELECTRICAL

DEFOGGER SYSTEM

BE–79

LEXUS RX300   (RM785E)

INSPECTION

1.

INSPECT REAR DEFOGGER RELAY CONTINUITY

Condition

Tester connection

Specified condition

Constant

1 – 4

3 – 5

Continuity

Apply B+ between

terminals 3 and 5.

1 – 2

Continuity

If continuity is not as specified, replace the relay.
2.

INSPECT REAR DEFOGGER RELAY CIRCUIT
(See page BE–18)

3.

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.
4.

INSPECT MIRROR DEFOGGER RELAY CIRCUIT
(See page BE–18)

5.

INSPECT DEFOGGER WIRE

NOTICE:

S

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.

S

Do not use detergents or glass cleaners with abrasive in-

gredients.

S

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

I01293

0 Volts

Broken
Wire

Several
Volts

Battery
side

Ground side

Foil strip

ę

Ĝ

I01294

Repair Point

Broken
Wire

Marking Tape

I01295

I07334

7

8

BE–80

–

BODY ELECTRICAL

DEFOGGER SYSTEM

LEXUS RX300   (RM785E)

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.

6.

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.

7.

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.

BE02C–12

The window moves down during the up operation.

1

With ignition switch ON, when performing the auto–up or manual –up
operation, if the factor which increases the sliding resistance of window
glass near the inverse position is recognized.

Disassemble the door and replace or repair the
component.

Reset the limit switch (See page BE–95).

If power window regulator and motor operate smoothly.

Yes

No

Check or repair door glass run and window guide
frame.

Replace the driver door control ECU with the normal one
removed from another seat.

Sliding  resistance check:

Power window motor reset:

Check operation power window control is normal.

Remove power window regulator assembly.

When raising the assembled window glass by hand if the glass slides
smoothly without being caught.

Yes

Sliding  resistance check:

Unit check:

Install power window regulator and reset the limit switch 
(See page BE–95).

Power window motor reset:

Check operation power window control is normal.

Power window motor faulty.

Yes

No

Normal.
(After checking the operation repeatedly, perform the
function check.)

No

Driver door control ECU faulty.

Yes

No

HINT: When difference of descending time comparing
to the opposite window is recognized, there seems to
be an error on sliding components (door glass run
and window regulator.)

–

BODY ELECTRICAL

POWER WINDOW CONTROL SYSTEM

BE–81

LEXUS RX300   (RM785E)

POWER WINDOW CONTROL SYSTEM

TROUBLESHOOTING

2

The DOWN function does not work though some other objects are caught in the power window glass.

Is the system in the jam protection function operating
condition?
  S The AUTO UP operation works with the ignition
switch ON. (One–touch operation)

Normal (Perform function check)

Normal
(After performing operation check repeatedly,
conduct the function check.)

Is the power window within the jam protection func-
tion operating area?

< Out of the operating area >
Area around the fully closed position

Reset the limit switch 

(See page BE–95).

Does the power window operate normally?

Master switch defective.

No

Yes

Yes

No

No

Yes

BE–82

–

BODY ELECTRICAL

POWER WINDOW CONTROL SYSTEM

LEXUS RX300   (RM785E)