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PostPosted: Fri Feb 12, 2016 10:22 pm 
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Joined: Mon May 19, 2008 10:30 pm
Posts: 8685
Location: Grand Rapids, Michigan
Year and Trim: 2014 Cadillac XTS Vsport.
Author - ddalder

Adding Heated Washer Solvent

This is another one of my traditional “long read” stories. There’s a lot of information here. Enjoy!

When I first looked at this project I purchased a heated washer solvent module originally made for the Cadillac DTS. There were both advantages and disadvantages to this. The bracket it came with was much easier to adapt for the Bonneville than the bracket for the full-size truck line. The down side, and it’s a big one, is the DTS module is intended to work with the vehicle instrument cluster. The DIC receives a PWM (Pulse Width Modulated) signal from the heated washer solvent module and will display messages about the status of the system. Unfortunately there is no way to make this work with the Bonneville. In the full-size truck line, the module will flash an indicator on the switch. This shows the status of the system and is far easier to implement in the Bonneville. Ultimately I ended up purchasing a module for the truck line but using the bracket from the DTS module. From the outside, both modules look identical and will easily clip into one bracket or the other.

A big consideration for this modification is power. This is a thirsty module and when operating requires 52 amps with the circuit is fused at 60A. The DTS comes with a 150A generator and a heavy duty battery. I felt reasonably safe since the GXP comes standard with a 140A generator and a heavy duty battery. This is a relatively small difference, not to mention the DTS has other power-consuming features not in the Bonneville. This probably factored in with Cadillac’s selection of a 150A generator. I certainly don’t recommend installing this with less than a 140A generator. Even in vehicles with the factory installed heated washer solvent there is some dimming of the headlights when it’s active.

There has been a lot of conversation in many different forums about whether this is truly a worthwhile option or just a gimmick. From my experience, and having used it now for two winters, I say it is most certainly worthwhile. There has also been much debate about whether it will crack windshields. I had a rock chip the entire first winter I used this and specifically decided not to have it repaired. Contrary to popular belief, it did not further crack with the use of heated washer solvent. The crack was in the area cleared by the wiper blades and received a direct spray of heated fluid. It’s important to remember that while the fluid is hot inside the heating chamber, by the time it actually travels through the tubing, out the spray nozzles and hits the glass it is much colder. Although by this point its “warm” but not hot, it is surprisingly effective. I rarely need to scrape my windshield. This is generally reserved for times where there is a heavy layer of ice. A good thick layer of frost is no challenge at all for the heated washer solvent.

There seems to be misconceptions about how this system works and how effective it is. First, the module does not reside in the washer fluid reservoir. The module mounts as close to the washer nozzles as possible. There are four cycles of heating and spraying. About 60mL of fluid is heated at a time. When at temperature, the washer pump is activated ejecting this onto the windshield and refilling the heating chamber. This cycle is repeated three more times (or until the operator presses the button again to stop the cycles). It takes up to 40 seconds to heat and start spraying for the first cycle and about 10-15 seconds for the following three cycles. In all, it’s about a two minute process. The module automatically controls the wipers when the washer pump starts spraying fluid. The aftermarket version of this product requires manual intervention by the driver to turn on the wipers during the spray cycle. The reason the module is mounted close to the spray nozzles is to minimize heat loss through the system plumbing.

Another misconception is the fluid in the reservoir is already hot enough based on warming from radiant engine heat. There is not nearly enough heat generated to warm 4+ litres of washer fluid and have the same effect. In fact, in some vehicles the washer fluid reservoir is either forward of the engine (not very helpful for radiant heat transfer when driving) or in an area separated from the engine by a barrier of some form.

Sadly, GM has discontinued this option. Just fewer than 1,000,000 vehicles were recalled due to the possibility a vehicle fire may occur. From my research, GM alleges a design flaw exists in the control circuitry and the module may over heat. It’s reported that in most cases a failure causes a small amount of smoke, a burning smell and the system will simply stop working. In a few cases a fire may result. It seems that GM has cut ties with Microheat, the company responsible for inventing the system. There is no “fix” implemented as part of the recall. What GM does is install a small wiring harness in-line with the control circuit wiring. This adds a 5A fuse to the ground wire of the control circuit. If the module fails because of the alleged engineering flaw, the fuse should blow before the control board overheats.

Now on to the modification...

This was one of my more challenging modifications simply due to the number of considerations in making everything “OEM”.

The module comes with a bracket and has two wiring connectors attached (one has been removed but is shown in the second picture). The smaller of the two is for control signals while the larger is for main power. I constructed two wiring harnesses. The first connects to the smaller connector and all but one wire is fed through the firewall near the passenger foot well. The remaining conductor is for ‘ACCY’ power and is routed into the fuse block in the engine compartment. Special connectors are needed as these are “sealed” for moisture reasons. The pigtail is available through ACDelco. The main power connector was removed entirely. The negative and positive wires bolt onto studs located on the bottom of the module. I considered purchasing a mating pigtail but when I found the cost to be anywhere from $305.00-$500.00 (depending on source) I elected not to.

This photo shows the module (I’ve already removed the high current connector):
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These are the high current and control connectors:
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The new 10 AWG wiring attached:
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This module is activated by pushing a momentary contact, normally open switch. The module begins a specific cycle of heating fluid then spraying while turning on the windshield wipers. In the vehicles GM installed this in, the heated washer solvent module grounds an input on the BCM responsible for controlling the windshield wipers. Because the Bonneville operates a little differently, additional modifications were required to make this work. The wiper control arm in a Bonneville provides a +12 VDC signal to the wiper/washer module when you push the wash button. Since the heater module provides a ground, the two aren’t compatible. My solution was to use two relays in the rear fuse block. Since the 2004 Bonneville doesn’t have the fuel door lock option (even though the relays exist), I was able to use this portion of the fuse block. The fuel door lock uses two SPDT relays, one to lock and one to release. I replaced these with SPST (very important to maintain correct function of the wiper/washer system). I use the heater module to ground the coils of these two relays. The contacts from one will supply +12 VDC to the wiper control line and the contacts from the other supply +12 VDC to the washer fluid pump.

In order to maintain a ‘stock’ appearance, it was necessary to modify the fuse block to accommodate a 60A circuit. It was necessary to disassemble, add parts and reassemble the fuse block to complete this portion.

The under hood fuse block is removed:
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Fuses and relays are removed:
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Bottom view:
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View with halves disassembled:
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Here is a picture with the new 60A circuit (black connector):
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The addition of an 'ACCY' power feed:
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This module must be mounted as close to vertical as possible (although a slight angle is okay). There is an air chamber at the top of the heating section in case the washer fluid freezes and expands. This will help to prevent a failure by cracking the casing open. Because of this, there are a limited number of places to attach this. Additionally, the heated washer fluid module needs to be mounted as close to the spray outlets as possible to avoid heat loss along lengthy washer hose. Fortunately I was able to mount this close to the firewall on the passenger side. Those who have a GXP will most appreciate the lack of under hood space available. I had to remove the stabilizer bar, coolant container and secondary air injection relay to facilitate addition of a wiring harness. It is possible with some adjustment in bends to use the mounting bracket.

Mounted module (fluid lines not connected yet):
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Another huge hurdle was the switch to activate the system. This was a long, difficult and tedious search. Sure, any old momentary N.O. switch will work, but the trick is to keep the factory/OEM appearance complete with symbol, text & backlighting. After finding no suitable solutions, I did some research into existing parts and decided to use a traction control switch.

The traction control switch is made using a multi-part process. It starts as a clear front button. It is painted white, then the final colour. In the case of the GXP the buttons are black. The button is then laser etched to reveal the white paint underneath. The backlighting is softened by, yet visible through this layer. The white is also crucial for daytime readability. I purchased a few traction control switches and cleaned off the finish with isopropyl plastic parts cleaner. An aerosol spray paint won’t come anywhere close to even layers so I purchased an airbrush. Paint was supplied by a local auto body supplier.

This is the process for preparing the switch:
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All the initial prep work is done and the button is ready to be laser engraved:
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Harofreak00 (Andrew) and his talent really helped me to pull this together. He skilfully created the artwork to help give this the true OEM look. I used a business in Calgary called Legacy Marking to do the engraving and was very happy with their workmanship. Here’s the finished product:
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And we can’t forget to post a night shot:
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I plan to relocate the actual traction control switch to a different location on the centre console.

The big reason I elected to use a module from the full-size truck line was to retain the indicator for system status. When I went to wire up the switch and indicator I discovered that GM changed the way both backlighting and indicators work in the newer generation vehicles. In the Bonneville an indicator will always have one side connected to ground. Whenever a module wants to indicate an “active” status it will apply +12V to the other side of the indicator. The new GM vehicles are opposite to this. There is 12V present on one side of the indicator all the time and any module wanting to show an “active” status will ground the other side of the indicator. This complicated things a little since the traction control switch I selected is not wired to support this.

To make all this work I had to provide +12V to the new switch all the time. This meant adding an extra pin to the circuit board and making some wiring changes. By cutting a couple of the traces I was able to rework the indicator circuit to work correctly with the heated washer solvent module. I used 30 AWG wire wrap wire to make the necessary changes. Because I had a few traction control switches around, the extra pin I added was off one of the other circuit boards.


Here is the switch in its original form:
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Now with some modifications:
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The new pin configuration is as follows:

1 – Ground
2 - Switch Signal (To the heated washer fluid module)
3 - Accessory Voltage (+12VDC)
4 - Back Lighting Control
5 - Empty/Blank (No pin in this position)
6 - Status Indicator Lamp Control (From the heated washer fluid module)

To accommodate the new circuit board I had to modify the switch housing. I expanded the original four cavity connector into a six cavity connector. You can see the new connector here:
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On the back of the switch, there is a moulded area where the electrical connector plugs in. I cut away a portion of this on one end. I used another switch and cut off a portion of this moulded area to transplant onto the original. Everything bonded very well using J-B Weld. The housing now accommodates a six cavity plug. What’s really nice is that the connector keying mates properly so it isn’t possible to plug the connector in backwards. It also clips on with the securing tab so the connector can’t work itself loose.
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The J-B Weld I used was the fast setting version. This was good and bad. It made the project go fairly fast, but I couldn’t make it look as nice as I hoped since it set very quickly. This means I’ve lost a little of the OEM appearance. Hopefully nobody has to take my dash apart and sees this. Some minor shaping with a Dremel will certainly “buff-up” the appearance. The indicator works and this is not only good but is important to maintain the OEM appearance and functionality.

Lastly I’ve included a photo of the small wiring harness GM installs as part of the recall:
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Update

Heated Washer Solvent - Update

Some time ago I added heated washer solvent to my Bonneville. This was quite a bit of work but there were a couple of items that I was never happy with.

I'm sure everyone has heard about GM's recall to remove this system from all vehicles. I gather in reading from various sources that there were three (major) revisions to this system in an effort to mitigate the possibility of a fire. My understanding is that by the third version, no suspected fires had been associated with this system. Regardless, GM opted to pull them all.

There is a "drop-in" replacement offered by AlphaTherm (known as the AT-37GM) that plugs into the vehicle the same way as the original. As with GM's approach, there are several different units depending on the vehicle it is being installed in. This is because some vehicles display a message on the DIC about system status whereas others use an indicator lamp in the switch. Otherwise, the biggest difference relates to the mounting bracket it is shipped with. I have upgraded to this drop-in replacement module.

What are the differences between the OEM module and the AT-37GM?

The indicator lamp functions slightly differently than the OEM version. When the wash cycle is canceled (by pressing the switch a second time while the system is active), or at the end of the normal heated wash cycle, the LED indicator will flash rapidly for ten seconds. With the original system the LED would simply stop it's slow, intermittent flash while active.

Secondly, the heat wash cycle "appears" to be a little different. I've noticed that it doesn't seem to be quite as effective as the OEM version, although it does still work well.

What's new with this project?

Those of you that read my original post will recall I had to modify the switch to make it function correctly with the heated washer solvent module. Harofreak00 created the graphic for the newly purposed "Traction Control" switch which a local company laser engraved on the face. In the vintage of systems used in the Bonneville, GM tended to ground one side of an indicator lamp and apply +12VDC to the other side when the system was active (Traction Control as an example). The heated washer module expected that +12VDC was always present on one side of the indicator and grounded the other side when the indicator illuminates. So, this meant providing a +12VDC signal to the switch at all times.

At the time of the original project I cut, drilled and bonded to merge different components to accommodate a six cavity connector (shown below). I added an additional terminal to the circuit board making the necessary changes by cutting some traces and connecting others using 30AWG wire-wrap wire.

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The first piece to the final upgrade was the switch housing. I contacted a vendor that was able to recreate the back portion of the switch housing for me. With the use of a 3-D printer, a custom part was born. It accepts the MicroPack 100 six cavity connector I had selected to use with the system. The engineer tightened up tolerances a little at the same time.

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Part two of this upgrade relates to the printed circuit board inside the switch. If you guessed that I had a custom circuit board made, you'd be correct! I actually had 20 of them made because it's the same price for a single as it is 20 (in this case).

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Here's a shot of the board populated and another with the board inserted into the custom housing component.

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Lastly, here are a few shots of the revised switch completely assembled.

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I'm very pleased with the final product and after several years can consider this project complete!

_________________
*Gone, but not forgotten* - Black 2000 SSEi, HIR Headlights, Angel Eyes fogs, 3rd brake light overlay, hi-flo cat, 180 degree thermostat, HS 1.9 rockers, LSx yellow springs, Intense FWI, PCM, shift kit, push rods, and 3.4 Pulley. ZZP Power Log.


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