Rain Sensor: Description and Operation
RAIN SENSORDESCRIPTION
The rain sensing windshield wiper system is a wiper system that, in addition to providing normal wiper functions off, mist, manual low speed, manual high speed, and washer, provides automatic control of automatic int, automatic low, and automatic high speeds.
OFF MODE
With the wiper switch "OFF" the ignition switch "ON" the rain sensor is considered to be in the "OFF" mode.
In this mode, the sensor commands the wiper motor to be "OFF".
AUTOMATIC MODE
When the multifunction switch is moved to auto position and the ignition switch is in the run or accessory positions, the rain sensor is considered to be in "automatic" mode.
Once a single "instant wipe" has occurred, the wipers remain at "inner wipe/park" until the rain sensor determines that the dwell time at that position is appropriate for the amount of precipitation an the windshield, rain sensor provides input to the wiper motor to activate the wipers to clear the precipitation from the windshield.
AUTOMATIC INT
For all automatic int, operations the rain sensor commands the wipers to operate in low speed for one wipe, followed by a variable dwell period in the inner wipe position.
AUTOMATIC LOW
Automatic low speed operation is utilized when the amount of precipitation impinging on the windshield exceeds the automatic int to automatic low threshold.
This threshold includes sufficient hysteresis to prevent cycling between automatic int and automatic low speed operation with a steady amount of precipitation accumulation on the windshield.
AUTOMATIC HIGH
Automatic high speed operation utilized when the amount of precipitation impinging on the windshield exceeds the automatic low to automatic high threshold.
This threshold includes sufficient hysteresis to prevent cycling between automatic low and automatic high speed operation with a steady amount of precipitation accumulation on the windshield.
WASHER MODE
The rain sensor monitors the multifunction switch to determine if the washer function is selected.
Rain sensor enables the wiper motor to run in low speed during the washer mode and performs wipes from 2.5 to 3.8 sec.
MANUAL MODE
The rain sensor determines when a manual mode such as manual low, mist, off or manual high is selected.
The column performs these modes and the rain sensor has no affect.
REPLACEMENT
The rain sensor module is mounted to the coupler using two snap fit stainless steel clips.
This allows the rain sensor module to be easily removed and replaced in the event of a rain sensor module failure.
If the windshield requires replacement, the existing rain sensor module may be unsnapped fro the original windshield and reinstalled onto the new windshield.
It is snap-fit to the new coupler, an integral portion of the replacement windshield as delivered by the replacement windshield manufacturer.
TROUBLESHOOTING
The rain sensor has two levels of fault detection as described below.
FAULT A
Fault A is indicated when the sensor has detected that the sensor servo operating point is above the expected limits. This is and indication of damage to the windscreen in the area of the coupler of the sensor has been removed from the coupler.
FAULT B
Fault B is indicated when the sensor has detected that it no longer is responding to rain signals.
This is an indication of damage to the windscreen in the area of the coupler or, more likely, that the sensor has detected and electrical failure within the sensor.
ATTACHMENT GRADE VALUE
Attachment grade is used to determine when fault in A is detected. The attachment grade value is set at 140. This allows the product to operate in all conditions other than the most severe damage the windscreen.
USE SENSITIVITY ADJUSTMENT TO INDICATE FAULT
A method to indicate detected faults is available to a service garage technician by using the sensitivity input and the wipers as an indicator. The service method is described as follows.
1. With ignition "ON", move the sensitivity adjustment to the high sensitivity setting.
2. Decrease the sensitivity by one setting.
3. If a wipe occurs, then Fault A has been detected and the service technician should assure that the coupler area on the windscreen is not damaged and the sensor is secured to the coupler.
4. Decrease the sensitivity one more setting.
5. If a wipe occurs, then fault B has been detected and the sensor should be remove and replaced with a known good sensor.
CAUTION:
When the ignition key is "ON" and the multi function switch is in the auto position the wiper could operate in the following conditions.
- Be careful not to touch the upper sensor front window glass.
- Be careful not to touch the upper sensor front window glass with a cloth.
- Be careful not to vibrate the front window glass.