by Bob Beranek

I received some interesting news recently about 2017-18 Honda CRVs equipped with Advanced Driver Assistance Systems (ADAS) and a rain sensor (FW04540-41). Although I can’t confirm at this time if this glitch applies to all Honda models, if the Honda model you are working on has both ADAS and a rain sensor, then I suspect the following procedure will be necessary when replacing glass in those models as well.

Honda CRV 2017

Honda CRV 2018

Dealers will tell you that all Honda model vehicles will require OE glass be installed before they can be recalibrated. With that being said, those of you who recalibrate with your own purchased tool may find that recalibration is possible with aftermarket glass, if the glass used is of good to excellent quality. The issue is the rain sensor.

If you install an aftermarket windshield, the rain sensor still may not work, even though the recalibration was a success, and even though it worked during the pre-inspection. The reason for the malfunction is what is called the Body Control Module (BCM).

Honda has an instruction note for installation that reads:

  • Make sure that there are no air bubbles between the windshield glass and the silicone sheet during installation;
  • If the automatic lighting/rain sensor connection is connected after the 12-volt battery terminal is connected, the automatic lighting/rain sensor is not confirmed by the body control module;
  • If the body control module does not confirm the automatic lighting/rain sensor, the automatic wiper system does not work.

This means that the BCM must be reset to recognize the lighting/rain sensor. How do we reset the BCM? In this case, the only way to reset the BCM is to disconnect the battery.

I know, disconnecting the battery should be discouraged whenever possible. Disconnecting the battery means that memory systems built into the vehicle can, and in most cases, will be lost. You will have to explain to the vehicle owner the possibility of lost memory to favorite features. However, here’s what needs to be done.

  • Disconnect the negative battery terminal;
  • Leave it disconnected for 15 minutes;
  • Reconnect the battery terminal and start the vehicle;
  • The vehicle will go through a reset protocol and reset the lighting/rain sensor; and
  • The radio can be reset by depressing the power “on” button 3-5 seconds.

After talking to several Honda dealers and dealer glass installers, I have heard that if an OE glass is installed, this BCM reset process rarely needs to be completed. So, you have a choice, stand around for 15 minutes waiting for the BCM to reset, or simply buy OE glass and be on your way. I will let you know when I learn more.

I had an inquiry recently from one of our Auto Glass University graduates. His question reminded me that there are some common problems that technicians should address when prepping a windshield with a rain sensor.

There are two types of rain sensor mountings. In one type the rain sensor is attached to a pre-applied lens, and the other is where the lens is part of the sensor and the unit uses an optically-clear pad to fill the gap between the lens and the glass surface. These two sensor mountings demand two different cleaning and preparation processes that must be completed properly or the rain sensor will malfunction.

11192015BobPic1First let’s talk about the easy one, the pre-applied lens. This is easy because the glass comes to us with a lens already applied to the surface so we do not have to worry about pads or mixing compounds. The sensor itself is usually attached to the lens with the help of clips or mounting hardware that is easily released and reattached.

You may think there is little we can screw up here, right? Wrong.

It is possible to disrupt the operation of this sensor by how you clean the glass. Most glass with a pre-applied lens come with protective tape covering the lens. This tape is used to protect the lens from handling mishaps that could damage the lens and cause malfunction. However, be aware of another use for the protective covering; to protect the lens from collecting glass cleaner overspray. If glass cleaner gets on the lens’ surface and air dries, the laser beam that causes the sensor to operate will be disrupted and the sensor will not work. It is impossible to clean the lens after glass cleaner is applied to it due to the rough surface and due to the possibility of scratching it with the cleaning towel. It is best to keep the protective tape on the lens until right before the sensor is reattached after replacement.

11192015BobPic2The next sensor mounting is the pad-mounted type. This type of sensor has the lens incorporated into the sensor itself. The optically clear pad that you obtain for replacement is used to fill the gap between the glass surface and the lens of the sensor. If there are any bubbles or other debris between the lens surface and the glass surface, the sensor will not operate properly because condensation can occur causing drops of water that will be detected by sensor. This leads to a malfunction. This type of sensor usually has a bracket attached to the glass that allows for proper alignment and clip retention. The inner part of this bracket can be cleaned before mounting and this is recommended.

It is always recommended that you replace the pads on every installation. I know. You have salvaged a pad here and there. I have, too, a few times. But, your luck does not always hold true, does it? If you do not want to have your customer inconvenienced, and you don’t want to pay the cost of going back out to do a remount of the rain sensor, then you will get in the habit of changing the pads on every job. Just do it.

To prep for this sensor mounting, it is important to have the pads and the glass at least at room temperature. This will allow the pads to stick properly to the lens and the glass with little or no bubbles. Lay the pad onto the sensor so air can escape out the sides. This is usually done by laying the pad in a bending fashion side to side.

If you choose to use the two-part liquid material, the material must have a convex shape above the sensors outer ridge and not cover the laser window. It is best to have the sensor on a flat surface when applying the material. Once applied it must also be cured a number of minutes before it is applied to the glass surface. Many technicians will attach the sensor to the glass before it is set in the opening.

So there you have it, prepping the glass for rain sensor mounting. I have but one more thing to add, make sure you pre-inspect the sensor before beginning the installation. If it didn’t work before you began the installation, odds are it won’t work when you’re done either.

A friend recently ran into an issue with a fully loaded 2014 Grand Cherokee with a rain sensor. He reported that after the new windshield was installed, the wiper swiped once every time the vehicle was started, and that when it rained the wiper did not change frequency and/or speed. His team had worked on several of these vehicles in the past and did not have a similar incident.

They took the vehicle to the dealer, where the dealer checked several on-lot vehicles and found that none of them had the same issue. The dealer contacted Chrysler Technical Services and discovered that the system needed resetting.

My friend told me by email, “In the scan tool there was an option asking if the RS had been removed or replaced. (By the way: I don’t think our auto glass tech unplugged it, rather he un-clipped it from the bracket on the windshield and left it hang.)  When ‘yes’ was selected the scan tool the system began resetting door locks, electro mirror, adaptive cruise and many other functions, including the ‘rain sensing windshield.’ After that was complete, the wipers performed normally.”

The charge for this service is about $50 to $75 per reset. The reset covers similarly-equipped vehicles from 2013 and up.

The unclear point in this story is that others have not had a similar problem when the glass was replaced. The tech in this case did not disconnect the rain sensor so interruption of the electrical circuit is not the cause.

My theory is that any Chrysler vehicle with multiple Advanced Driver Assist Systems (ADAS) included in its features, requires this reset/recalibration. I think that all ADAS circuits are interrelated and need rebooting. I would be interested to hear from those that have had a similar experience and how they handled it.