Moisture Sensing Automatic Windshield Wipers
There is no doubt that this is a pretty neat option. In comparison with some of my other modifications, this one was fairly straight forward. This can be added with a varying degree of effort and difficulty. The more ‘OEM’ in appearance, the more time and work is involved.
Outside moisture sensor (From a ’01-’03 Aurora or a ’00-’05 LeSabre)
Outside moisture sensor windshield mounting kit.
Outside moisture sensor trim cover (for ‘first design’ sensor only).
You’ll also need:
A portion of headliner wiring with the moisture sensor connector attached.
Wire for making the new sections of the harnesses.
The outside moisture sensing wiper option is available on a few other GM vehicles. The sensor communicates directly with the wiper motor module. This a relatively easy install because the ’01-’03 Aurora and the’01+ (perhaps earlier) LeSabre had this as an available option AND the wiper motor module in the Bonneville is the same as these two cars.
The moisture sensor works by reflecting infrared light off the outside surface of the windshield and measuring how much is returned to the sensor. When moisture is present, the light is reflected in other directions reducing the amount returning to the sensor. Based on this, the sensor will command the wiper motor to activate. The more moisture, the faster and/or more frequent the wipers will operate.
The sensor communicates with the wiper motor module by way of PWM (pulse width modulated) signals. There is a signal sent from the sensor to the wiper motor module and another returned from the motor module back to the sensor. When the wiper motor module detects ongoing communication, the ‘Delay’ function on the wiper control arm adjusts the sensitivity of the sensor. If the wiper motor module is unable to communicate with the sensor, the motor uses the input from the wiper control arm to adjust the amount of ‘Delay’ between wipes. This is the default on the Bonneville since the two required connection on the wiper motor module for this option are simply not connected.
OVERCOMING THE HURDLES
This required some phone calls and a little research. The big question for me was whether or not the glass was specially treated or processed somehow over the location of the sensor (perhaps similar to how the glass is made for the HUD). After speaking with someone at a glass manufacturing plant, I found that the glass itself is no different than any other, only that the mount is attached. This is a special process since there is a pad and special adhesive that will stick the mount to the glass. The adhesive pad should be a specific thickness and as clear and free of distortion as possible in order for the light to travel through. Since there is no other car that shares the size and shape of the Bonneville glass (reminds me of the same issues I had with my mirrors when I wanted to add turn signals), this became a potential problem. Although the LeSabre is also an ‘H-Body’, the glass is very different. The Aurora windshield is also not an option. Without the correct mount, this is not doable.
Further research and help from a local glass shop led me to a part available from C. R. Laurence. These folks manufacture many different items for windshield and glass replacement. The mount kit is part number RCK-1427. The Moisture Sensor Mount should be available through most auto glass shops for between $35-45. Once I knew there was a way to mount the sensor, I was off to the races.
I chose to make this look fairly ‘OEM’. This meant I had to remove the headliner from the car, add wiring to the pre-existing headliner harness and then continue on from the left ‘C’ post to the front of the car, through a body pass-through and up to the wiper motor module harness.
One of the most important steps is to get the old hot tub out so there is room for the new one. As you can see, my friend built his deck around the tub. The hot tub company was going to charge $150.00 to lift it out if we needed them to (although they did take away the old carcass for free). We were able to use a hydraulic floor jack and some effort to get it out of the way. Personally, I was getting ready to just pay the money!
Why is this important you ask?? Because when you want to use the hoist at your friends’ shop to complete the project, and elicit a little assistance, it will help to “grease the wheels” a bit.
With the hot tub out of the way, it’* time to carry on...
INSTALLATION PROCEDURE - WIRING
The first task is to remove the headliner. This wasn’t too difficult but required the removal of all three grab handles, the ‘A’, ‘B’ and ‘C’ pillar trim panels along with pulling the door seal down slightly from the top of the door openings. There are two connectors that must be unplugged. The first is an 18 cavity GT 150/280 Series Lever Lock at the base of the left ‘C’ pillar. The other is a 6 cavity Metri-Pack 150 connector clipped to the headliner at the top of the right ‘C’ pillar. The panel is held up by some magnets in the back and centre. Towards the front, there is an almost Velcro type material. It is important to handle the headliner carefully or it will crease. It should be removed through the right rear door. The FSM indicates if the vehicle doesn’t have a sunroof to remove it from the right front door, but I’m not exactly sure how this is possible.
GM hot glued the headliner harnesses to the top of the headliner. Instead of taking it apart, I built a second harness and hot glued it tightly beside the existing left harness. I tied into the OEM Lever Lock connector that connects to the left ‘C’ pillar. Since the wrecker provided about 16 inches of harness for the sensor, I connected my new section of harness to the pigtail with a four conductor Delphi connector. This allows everything to remain essentially ‘OEM’.
The sensor only requires 4 connections. These are:
1. Accessory Power
3. Rain Sense Signal 1
4. Rain Sense Signal 2
I connected the ground wire to an existing ground in the headliner harness. This meant I only needed to pass three signals through the 18 cavity headliner harness. I spliced the connection and then insulated it with heat shrink tubing.
Here you can see the new moisture sensor connector coming off the headliner along with the rear view mirror connector.
I built and added a three wire harness that I connected to the vehicle side of C329 (Headliner to Left Body Harness Connector). This section of harness was routed along with much of the other rear body harness through the trunk, down behind the rear seat back, under the rear seat cushion and up along the left side of the body underneath the carpeting.
The accessory voltage wire was connected to one of the large 40 cavity connectors at the base of the steering column. Coincidentally, this is where power is located for the windshield wiper circuit. By using this point, it is fused along with the windshield wiper circuit (as it would be with the Aurora or LeSabre).
The two remaining wires (Rain Sense Signal 1 and Rain Sense Signal 2) need to be run through the fire wall. In order to facilitate this, my friend and I pulled the entire harness back from the engine compartment into the driver side foot well. This allowed easy access to the P100 (the wiring pass-through) so I could un-wrap it and add the new wires. This sounds a lot more difficult than it really is. This is where the hoist really helped (although not absolutely necessary). My friend removed the plastic panel under the front of the car and the air box. There were a few connectors to be unplugged (cruise control, brake fluid level, windshield wiper harness, body to engine harness and airbag sensor). There were a few clips holding the split-loom to the body and once these were released, it was easy to pull the whole harness back. My friend Rob has been a mechanic for near 20 years and is very good. His help was great and really improved time to completion. This mod would have taken much longer without his expertise under the hood.
I purchased a supply of Metri-Pack 150 sealed terminals along with the correct Delphi crimp tool. This allowed me to add the wiring to the inline harness connector under the hood that ultimately connects to the windshield wiper motor module. This inline connector is clipped onto the left strut tower on the side facing the right strut tower and has 7 cavities.
Here is the addition of the two wires into the under hood connector for signals ‘Rain Sense Signal 1’ and ‘Rain Sense Signal 2’.
The last section of harness runs from the left strut tower back towards the fire wall where it plugs into the wiper motor module. Interestingly enough, this short section of harness already has the wiring required. This suggests that the same short section of harness is also used in the LeSabre and the Aurora.
I figured I’d try and be smart about things and so I decided instead of only running the two required wires, I ran an additional 6 (0.50mm2 / 20 AWG). I got a sealed connector from the auto wrecker and inserted new wires, terminals and cable seals on one half. The mating half of the connector has cavity seals in all positions but is plugged into the wired half. This way everything remains clean and dry until I need it. It will be terminated on the inside of the vehicle to a standard OEM style Metri-pack connector.
While I was making the final connection for 'Accessory Power' running back to the headliner harness, my friend was reinstalling the harness under the hood and getting the air box back in place.
INSTALLATION – MOISTURE SENSOR MOUNT
The next step is attaching the mount to the glass. This is applied a few inches directly below the rear view mirror. There is a plastic cap that snaps onto the mirror base (on the end towards the defrost vent, not towards the headliner). This piece needs to be removed in order for the sensor cover to snap on in its place.
To determine where the sensor mount is to be positioned, I attached the sensor cover and then placed electrical tape on the outside of the glass at each edge of where the cover sits. Using this, it is easy to estimate where the mount needs to be positioned between the electrical tape edges.
Application of the two-sided adhesive pad for the mount is a bit tricky. It is made of a fairly soft material and pressing too firmly with fingers or other objects can create grooves. These will make it difficult (if not impossible) to attached the rigid mount without getting air bubbles. If this happens it may affect the operation of the sensor.
The glass needs to be treated with a type of primer that helps to create a better bond between the adhesive pad and the glass. Follow the directions enclosed with the mount kit very carefully. When applying the adhesive pad, it’* advisable to start at one edge and work down. I would advise very gentle pressure to start. Once the tape is applied, do the same for the mount. As soon as it’* in place, pressure can be applied to the whole assembly to ensure it adheres well.
The sensor has two clips that will snap into place on the edge of the mount. Once this is done, plug in the connector and snap the cover in place.
Here’* a video. You need to make sure that the wiper blades are in good condition. If they streak, you can end up having the wipers run longer than usual.
In a couple of other videos I didn't post, it'* possible to see that the more water my friend poured on the window, the faster the wipers operate. Thanks for all your help, Rob.
Edits: Grammatical, Additional Pics