Rain Sensor Circuit: Procedure

1. Check the symptoms of the wiper. Check if the symptoms can be corrected with the information below.
   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, it does not operate when outside temperature is 70°C (158°F) or more, or when sensor's interior temperature 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

   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 furthermore replacement of rain sensor does not correct problem, wiper motor may be malfunctioning.

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   13 

OK: Go to next step 

1. Set the windshield wiper switch to AUTO, and check the problem symptom.
   RESULT
   
   

   Problem Symptom	Proceed to
   It is raining but wiper does not operate	A
   It is not raining but wiper operates	B

B → See step   9 

A: Go to next step 

1. Check the vehicle.
   RESULT
   
   

   Problem Symptom	Proceed to
   Wiper operation 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 wiper's ability to wipe.

   OK

   No residue after wipe

NG → See step   16 

OK: Go to next step 

1. Check that the rain sensor is installed properly.

   OK

   When viewed from outside vehicle, rain sensor's tape is not peeling, and has no air bubbles or dust

NG → See step   17 

OK: Go to next step 

1. Check the Data List for proper functioning of the rain sensor. Refer to DATA LIST / ACTIVE TEST [09/2012 - ] .
   RAIN SENSOR:
   
   

   Tester Display	Measurement Item / Range	Normal Condition	Diagnostic Note
   Sensor Low Temp Info	Rain sensor cold / NG or OK	NG: Rain sensor low temp OK: Rain sensor normal	-
   Sensor High Temp Info	Rain sensor cold / NG or OK	NG: Rain sensor high temp OK: Rain sensor normal	-

   OK

   Rain sensor operates

NG → See step   14 

OK: Go to next step 

1. Set the windshield wiper switch to AUTO. Wet a swab and squeeze the tip so that it is 4 to 6 mm wide. Touch the swab to the rain sensor detection area and check that the wiper LO operation occurs once.
   RESULT
   
   

   Malfunction Operation	Proceed to
   Wiper operates 3 times or more	A
   Any other operation	B

B → See step   14 

A → See step   15 

1. Check that the rain sensor is installed properly.

   OK

   When viewed from outside vehicle, rain sensor's tape is not peeling, and has no air bubbles or dust

NG → See step   17 

OK → See step   14 

1. Check that the rain sensor is installed properly.

   OK

   When viewed from outside vehicle, rain sensor's tape is not peeling, and has no air bubbles or dust

NG → See step   17 

OK: Go to next step 

1. Disconnect the X4 map light connector.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

2. Measure the voltage according to the value(s) in the table below.

   Standard voltage

   Tester Connection	Switch Condition	Specified Condition
   X4-9 (IG) - Body ground	Engine switch on (IG)	11 to 14 V

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Disconnect the X4 and X6 map light connectors.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

2. Disconnect the X8 ECU connector.
3. Measure the resistance according to the value(s) in the table below.

   Standard resistance

   Tester Connection	Condition	Specified Condition
   X4-8 (IG2) - X8-4 (SIG)	Always	Below 1 Ω
   X6-19 (GND2) - X8-1 (ES)	Always	Below 1 Ω
   X4-8 (IG2) - Body ground	Always	10 kΩ or higher

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK → See step   13