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Last Modified: 11-27-2007 1.6 J
Service Category: Vehicle Exterior Section: Wiper/Washer
Model Year: 2008 Model: LX570 Doc ID: RM000002OXK006X
Title: WIPER / WASHER: WIPER AND WASHER SYSTEM: DESCRIPTION (2008 LX570)

Rain Sensor Circuit

DESCRIPTION

The auto wiper system adjusts the wiper speed to the optimum speed based on the amount of rain. The rain sensor mounted on the windshield detects rainfall. This system operates when the windshield wiper switch is set to AUTO. The rain sensor sensitivity can be adjusted with the rain sensor adjusting switch. Signals are sent to the windshield wiper ECU from the windshield wiper switch through the CAN line, and from the rains sensor through the LIN line. Based on these signals, the windshield wiper ECU operates the wiper and determines its operation speed.

WIRING DIAGRAM

INSPECTION PROCEDURE

PROCEDURE

1.

CHECK WIPER

(a) Check the symptoms of the wiper. Check if the causes of the symptoms are any of the following conditions shown in the charts.

It is Raining but Wiper does not Operate

Condition

Note

Windshield wiper switch in position other than AUTO

Wiper only operates at AUTO setting

Rain sensor temperature is -10°C (14°F) or less, or 70°C (158°F) or more
  • To prevent improper operation, wiper does not operate when rain sensor temperature is -10°C (14°F) or less
  • To prevent damage to rain sensor, wiper does not operate when outside temperature is 70°C (158°F) or more, or when interior temperature of sensor is 90°C (194°F) or more

It is drizzling, or there is scattered rain

If rain droplets do not contact rain sensor, or rain droplets are very small, they are not detected

It is not Raining but Wiper Operates

Condition

Note

Condensation on windshield

Wiper may operate if condensation occurs in rain sensor detection area. If condensation recurs after rain sensor detection area is wiped, wiper operation may continue.

Sun rays are strong

If sudden changes in light intensity occur, wiper may operate

Sudden temperature changes

If sudden changes in temperature occur (A/C heater is used in winter, etc.), wiper may operate

Object is contacting rain sensor

If inner mirror contacts or strikes rain sensor, wiper may operate

Windshield wiper switch off by AUTO

Wiper operates 1 time after windshield wiper switch is turned off by AUTO

Wiper Operation is Irregular

Condition

Note
  • Wiper blade is deteriorated
  • Windshield surface is oily

Rain sensor detects rain amount when wipers are operating. When rain is not completely wiped off by wipers, decrease in ability to detect amount of rain occurs.
  • During scattered rain
  • Heavy rain with large droplets
  • During scattered rain or when rain droplets are large, rain droplets contact the sensor intermittently, causing wiper operation to be irregular
  • During heavy rain, it is difficult for sensor to learn "no rain" condition, causing wiper operation to be irregular

Wiper volume is set to minimum

Minimum wiper volume setting is designed to be non-sensitive (for users who prefer non-sensitive operation), resulting in irregular wiper operation

Problem with wiper motor position signal

When wiper motor position signal has chattering, wiper may operate excessively. During auto wiper operation inspection, if wiper operates several times, and replacement of rain sensor does not correct problem, wiper motor may be malfunctioning.

OK:

Causes of symptoms are one or more of above conditions

OK

2.

CHECK WIPER OPERATION

(a) Set the windshield wiper switch to the LO and HI setting, and check that the wipers operate normally.

OK:

Wipers operate normally

OK

3.

CHECK WINDSHIELD WIPER SWITCH

(a) Set the windshield wiper switch to AUTO, and check the problem symptom.

Result

Result

Proceed to

It is raining but wiper does not operate

A

It is not raining but wiper operates

B
A

4.

CHECK OPERATION OF WIPER

(a) Check operation of the wipers.

Result

Result

Proceed to

Wiper does not operate normally

A

It is raining but wiper does not operate

B
A

5.

CHECK WIPER RUBBER

(a) Activate the washer and check the wiping ability of the wiper.

OK:

No residue after wipe

OK

6.

READ VALUE USING TECHSTREAM (COMBINATION SWITCH)

(a) Using the Techstream, read the Data List.

Body No. 5

Tester Display

Measurement Item / Range

Normal Condition

Diagnostic Note

Wiper Auto Switch

Front wiper AUTO switch / ON or OFF

ON: Front wiper switch in AUTO position

OFF: Wiper switch not in AUTO position

-

OK:

Windshield wiper switch operates.

OK

7.

CHECK RAIN SENSOR

(a) Check that the rain sensor is installed properly.

OK:

When viewed from outside of vehicle, rain sensor tape is not peeling and has no air bubbles or dust on it, and sensor has not come off bracket

OK

8.

READ VALUE USING TECHSTREAM (RAIN SENSOR)

(a) Using the Techstream, read the Data List.

Rain Sensor

Tester Display

Measurement Item/Range

Normal Condition

Diagnostic Note

Rain Sensor Cold

Rain sensor cold / COLD or OK

COLD: Front wiper switch in AUTO position

OK: Wiper switch not in AUTO position

-

Rain Sensor Hot

Rain sensor cold / HOT or OK

HOT: Front wiper switch in AUTO position

OK: Wiper switch not in AUTO position

-

OK:

Rain sensor operates.

OK

9.

CHECK RAIN SENSOR

(a) Set the windshield wiper switch to AUTO. Flatten the end of a cotton swab soaked with water so that it is 4 to 6 mm (0.157 to 0.236 in.) wide. Touch the swab to the rain sensor detection area and check that the wiper LO operation occurs once.

Standard Measurement

Area

Specified Condition

A

7 mm (0.276 in.)

B

22 mm (0.866 in.)

C

16.6 mm (0.654 in.)

D

26.6 mm (1.05 in.)

E

12 mm (0.472 in.)


Result

Result

Proceed to

Wiper does not operate

A

Wiper operates normally

B

Any other operation

C
A

16.

CHECK RAIN SENSOR

(a) Check that the rain sensor is installed properly.

OK:

When viewed from outside of vehicle, rain sensor tape is not peeling and has no air bubbles or dust on it, and sensor has not come off bracket

OK