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Automatic wipers wipe with no moisture

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I recently had the windshield replaced on my 2018 MKZ due to multiple chips. Subsequent to the replacement the automatic wipers sense rain when there isn't a cloud in the sky. It isn't consistent but is likely to happen several times in any trip of 10 minutes or more. One wipe and then they reset to the parked position properly.

 

The windshield company assures me that it has nothing to do with the replacement or calibration but web research suggests otherwise. Has anyone any information or suggestions about how to address this problem?

 

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The crux of your question seems to be 'Something has changed' and 'What can I do about it'.

 

In this case, the existing rain sensor was removed from the faulty windshield and remounted to the replacement windshield, with more-than-previous spurious wipes occurring after the repair was completed.

 

Let's start with the technical, and then we'll address the practical.

 

Rain sensor photo from FordParts.com...

 

218852261_2018MKXWindshieldWiperRainSensor.jpg.d7bb7ba2033c471da54644cdedcac92e.jpg

 

From the 2018 MKX Workshop Manual...

 

Rain Sensor

The rain sensor uses an infrared beam to optically sense water on the windshield. The intensity of the reflected beam is measured and compared to the intensity of the transmitted beam. If there is water on the surface of the windshield the beam distorts, reducing the intensity of the beam. If the beam is not reflected completely, it is interpreted as rain on the windshield and the windshield wipers are activated.

 

A gel-type lens is used as the interface between the rain sensor and the windshield. If the lens is missing or damaged, the rain sensing wipers can be inoperative. The rain sensor gel-type lens cannot be replaced separately on a rain sensor of this type.

 

Rain Sensitive Wipers (if equipped)

When equipped, the rain sensitive wiper feature replaces the intermittent wiper feature. The rain sensitive feature is active when the wiper/washer switch is in any of the 6 auto/intermittent sensitivity settings. The setting closest to OFF is the least sensitive to moisture, the highest setting being the most sensitive to moisture.

 

The rain sensor sends data through the LIN to the windshield wiper motor. Based on the data received from the rain sensor and the auto/intermittent setting from the wiper/washer switch, the system automatically activates and adjusts the wiper speed and frequency when moisture is detected on the windshield.

 

If a fault is detected with the rain sensitive feature, the windshield wipers change to a default intermittent mode. The timing of the wipers correspond to a standard intermittent setting based on the auto/intermittent sensitivity setting on the wiper/washer switch.

 

Intermittent Wipers

When the wiper/washer switch is in an intermittent setting, the windshield wiper motor activates at timed intervals. The lower the setting, the longer the interval between wipes.

 

Wiper/Washer Switch

The wiper/washer switch is mounted directly to the SCCM . The windshield wiper/washer inputs to the SCCM are:

  • Mist wipe
  • Windshield wash
  • Off
  • AUTO 1/INT 1
  • AUTO 2/INT 2
  • AUTO 3/INT 3
  • AUTO 4/INT 4
  • AUTO 5/INT 5
  • AUTO 6/INT 6
  • Low
  • High

 

Workshop Manual diagnostic Pinpoint Test "F", edited to focus upon Rain Sensor function...

 

F7 CHECK THE WINDSHIELD GLASS FOR STREAKING
  • Ignition ON.
  • Turn the wiper/washer switch to the low speed wiper setting and while applying water to the windshield surface. Observe the wipe quality, especially around the area of the rain sensor.

Is any streaking present on the windshield around the area of the rain sensor?
 
Yes GO to F8
No GO to F10

 
F8 CHECK THE WINDSHIELD WIPER BLADES FOR STREAKING
  • Ignition OFF.
  • Clean the windshield glass with glass cleaner.
  • Clean the wiper blades with isopropyl alcohol swabs. Wipe the entire length of the wiper blades.
  • Ignition ON.
  • Place the wiper/washer switch to the low speed wiper setting and while applying water to the windshield surface. Observe the wipe quality, especially around the area of the rain sensor.

Was there noticeable improvement in the wipe quality after cleaning the glass and the wiper blades?
 
Yes GO to F9
No INSTALL new wiper blades. GO to F9

 
F9 RECHECK THE RAIN SENSITIVE WIPERS OPERATION
  • Place the wiper/washer switch to the auto/intermittent 5 setting (most sensitive to moisture) while applying water on the windshield above the rain sensor.

Do the wipers operate when water is applied to the windshield surface?
 
Yes The system is operating correctly at this time. The concern may have been caused by poor wipe quality on the windshield around the rain sensor.
No GO to F10

 
F10 CHECK FOR THE PRESENCE OF THE LENS GEL
  • Ignition OFF.
  • Lightly press the rain sensor against the windshield and release the rain sensor clips.

Does the rain sensor remain adhered to the windshield?
 
Yes ATTACH the retaining clips. GO to F11
No

The sensor gel-type lens is missing or damaged. INSTALL a new rain sensor.
REFER to: Rain Sensor (501-16 Wipers and Washers, Removal and Installation).

 

PDF download link to document > Rain Sensor - Removal and Installation - 2018 MKX Workshop Manual.pdf


 
F11 INSPECT THE RAIN SENSOR MOUNTING AREA

NOTE: The rain sensor gel-type lens can be damaged or contaminated during rain sensor removal, rain sensor bracket separation or incorrect installation.

  • From the outside of the vehicle, inspect the area of the windshield glass where the rain sensor is mounted. The rain sensor contact area should appear black, with no bubbles, air pockets or contaminants between the windshield glass and the rain sensor.

Does the rain sensor contact area appear black, with no bubbles, air pockets or contaminants between the windshield glass and the rain sensor?
 
Yes GO to F12
No REMOVE and INSTALL the rain sensor correctly.
REFER to: Rain Sensor (501-16 Wipers and Washers, Removal and Installation) > PDF download link in Step F10 section, above.

TEST the system for normal operation.

 

 

 

And now, on to the practical: Color augmented 2018 MKX Owners Manual section and Wiper-Washer Multi-Function Switch photo from FordParts.com...

 

159559721_2018MKXOwnerManual-WipersandWasherspage.jpg.c74cfcd1d13957e8771058ea2c169a1c.jpg 1208980071_2018MKXMultifunctionWiper-WasherSwitch.jpg.918678a922a6b7eaec3c5b141849245b.jpg

 

Observations from immediately above...

 

Yellow box - A dirty/dusty windshield in vicinity of rain sensor can cause spurious wipes;

 

Green box - Setting sensitivity to low, in photo, green arrow, diminishes risk of spurious wipes;

 

Orange circles and in photo, orange arrow - moving right stalk upward or downward, sets high speed wipe, low speed wipe, autowipe (rain or intermittent), off/no wipe, mist wipe.

 

After performing Pinpoint Test "F" conditional evaluations, if spurious wipes are still a problem, just set the stalk in "Off" position to eliminate spurious wipes.

 

The following are PDF download links to relevant Workshop Manual sections...

 

Wipers and Washers - System Operation and Component Description - 2018 MKX Workshop Manual.pdf

 

Rain Sensor - Removal and Installation - 2018 MKX Workshop Manual.pdf

 

Interior Rear View Mirror - Removal and Installation - 2018 MKX Workshop Manual.pdf

 

Good luck!

 

Edited by Haz

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