Rain Sensor Circuit: Procedure

1. 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

NG → See step   2 

OK → END 

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

   OK

   Wipers operate normally

NG → See step   11 

OK: Go to next step 

1. 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

B → See step   10 

A: Go to next step 

1. Check operation of the wipers.
   RESULT
   
   

   Result	Proceed to
   Wiper does not operate normally	A
   It is raining but wiper does not operate	B

B → See step   10 

A: Go to next step 

1. Activate the washer and check the wiping ability of the wiper.

   OK

   No residue after wipe

NG → See step   14 

OK: Go to next step 

1. 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.

NG → See step   16 

OK: Go to next step 

1. 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

NG → See step   15 

OK: Go to next step 

1. 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.

NG → See step   12 

OK: Go to next step 

1. 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.)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   RESULT
   
   

   Result	Proceed to
   Wiper does not operate	A
   Wiper operates normally	B
   Any other operation	C

B → END 

C → See step   17 

A → See step   13 

1. 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

NG → See step   15 

OK → See step   12