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Old 12-06-2014, 12:44 PM   #1
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Join Date: Mar 2014
Location: Mountain Top, PA
Posts: 44
My Ride: SE46
E46 Windshield Wipers WITHOUT GM5

I realize this post is a bit lengthy, but please read the entire thing if this is something you are interested in doing. The final diagram shown will work but has some quirks that may not be desirable for you and would be best for you to know what these are so that if you do it you could better troubleshoot it in the middle of a race.

I have seen the question of if you need GM5 in a SE46 car or not come up multiple times already. The simple answer is no. It has nothing to do with EWS, and will not affect the cars performance at all. For more information about GM5, please see: http://www.bmwgm5.com/

Originally Posted by www.bmwgm5.com FAQ
#2 Will my car work without the general module?
Yes, the car will still run and drive fine without the general module. You will loose a few things like power windows, power door locks, remote keyless entry, remote trunk release, trunk release switch (the key will still work in the keyhole) interior lights, windshield wipers, windshield washers and alarm. Other than that you probably won't even notice the module is missing.
As you can see, the most useful thing that you would loose if you removed GM5 is the windshield wipers. Additionally the windshield washers if you want to run one, and the electric trunk release if wish to retain that.

Below is the factory wiring for the windshield wipers (click the diagrams for a larger version):

In short, GM5 uses logic based on the wiper switch position to control the windshield wiper relay, and thus the motor.

To run the wipers without park, without GM5 is simple. The connections you need to make can be done right near the GM5 connector X253. You don't need to dig through the harness, pull wires, or run new wires.

De-pin (or cut) the following wires and temporarily make the following two connections out of the four wires.

X253-3 SW/WS
X253-11 BR/BL

X253-1 SW/BL
X253-30 BR/WS (Schematics are showing this as BW/BL but it was BW/WS on my car. I added the pin numbers, wire colors and sizes to the modified diagram.)

F59 is always powered, so as long as your battery is connected (and kill switch is on), the wipers will work, regardless of the ignition switch position. Try it out...

- One click up to intermittent will energize the high speed coil in the wiper relay, but the wipers will not turn on. You may hear the wiper relay (located in the DME box) click. This won't hurt anything, but just how it will be. Turning the speed adjustment dial will have no affect on anything.
- Two clicks up to slow speed will turn the wipers on at low speed.
- Three clicks up to high speed will turn the wires on at high speed.

Without the park switch in use, the wipers will stop where ever they are once you turn them off. But there is one more setting on the switch, Mist. Without GM5 and having it wired like this, the wipers will run on the slow speed for the duration you hold the wiper switch down on the mist setting. This is actually very convenient to manually park the wipers as it much easier to turn the wipers on and off for a short duration using the mist switch vs going through the detents of the switch for int/low/high.

If you are content with how the wipers are working right now (especially after looking at the following schematic and reading the quirks of it), make proper crimp connections of the two temporary ones. If you're digging into the harness and removing the excess wires, make these connections right between the wiper switch and where the large bunch of wires go through the firewall on the left side, as the wiper relay is in the DME box, vs having the wires cross over the transmission hump. But if you don't want to dig into the harness, you can just do it right near the X253 connector for GM5.

Note: Doing the above reusing the factory switch is the easiest way, but this method, and the one below will reuse the factory wiper switch in an unintended method. The current for the wiper relay coils will be going through the wiper switch, and although this is low, it may shorten the life of the switch. I did not measure before or after, so it's just a precaution to note. I have a spare switch, and they are easy to change. Additionally, there is no reason you couldn't use a different switch if you don't want to keep the factory switch on the column, but still retain the factory wiper relay. You should be able to figure that out on your own from the schematic above.

Below is my first idea to be able to have the wipers to self-park, and although it does work I do not feel it is the most ideal way. I've shown the diagram to some other people and discussed some of the issues it has and alternative methods but I am not sold on any one way yet. I figured I would post it and list the problems so that more people can see it, and either use it knowing the problems, or perhaps someone else can come up with a better solution.

The park switch is located inside of the wiper motor, and is closed while in the park position, connecting pin 4 to ground. By adding a standard automotive SPDT relay we can use this park switch to keep the wipers running until they are parked. The relay will simulate having the wiper switch on low, until the park switch closes. But, since the park switch is grounded while in park, we need to use a normally closed contact on the relay. While in park, the switch is closed, and therefore allowing the relay coil to energize and open the normally closed contact, and will stop the motor, since the wiper relay coils will not be grounded by either the wiper switch or the new relay. If you turn off the wipers while they are not in park, the wiper relay coil would typically loose it's ground from the wiper switch, but since the new relay coil would not be energized because of the open park switch, the normally closed contact will be made, and allow the low speed wiper relay coil to be grounded and thus keep the wiper motor running until the park switch is closed causing the new relay coil to energize and to open the normally closed contact.

Not too difficult ... but this method has some issues:
- An audible CLICK every revolution of the wipers from the new relay. With a helmet on, and the car running this shouldn't be a problem. The relay can be mounted anywhere, and maybe others are quieter, such as a solid state relay.
- If the new relay coil is not energized (loss of power, or loss of ground from a broken wire or bad park contacts), while the wiper relay still has power, it will allow the wipers to run on low speed, ALL THE TIME, regardless of the wiper switch position because of the normally closed contact.
- F59 is always powered with the battery connected and kill switch on. If you ever park your car without turning off the kill switch, the new relay coil will need to be energized the entire time the car is sitting to prevent the wipers from running, as mentioned above.
- We can switch F59 to another fuse position that is switched via the ignition switch, and then the above problem can only happen when the ignition switch is on.
-F59 and pin 85 of the new relay should be have the same type of power source, it can be the same power source but doesn't have to be. If you keed F59 always powered via the battery, pin 85 has to be also (can be connected to F59, or another now unused always hot fuse). If you switch F59 on and off, pin 85 should be switched on and off at the same time.
- Using a relay socket would allow you to unplug the entire relay to stop it if it was to start running non-stop on it's own. The wipers would continue to work exactly as the diagram and section of WITHOUT park.
- Install a SPST switch between the relay 87a pin and the splice into the wire of X295-1 and X1242-1. This would act like an on/off switch for the park feature only. Turning this switch off would work the same way as unplugging the entire relay.
- Use a DPST switch instead of a SPST, and also be able to cut the power to the new relay coil. This would be more useful if pin 85 was connected to F59, where both the new relay and wiper relay share the same power. This way if a short is created from the new relay coil or wires, and it blew F59. You could isolate the new relay from the system and get the wipers working again.

Thoughts of alternative methods:
- Make a new disc inside of the wiper motor so that the park switch works opposite of how it does now. The park switch would be closed while not in park, and open while in park. Then the new relay would work exactly like the wiper switch and you would use a normally open contact. While not in park, the relay coil would be energized closing the normally open contact to keep the wiper relay coil energized. Once in park position the park switch would open, and the new relay coil would no longer be energized and the allow the contact to return to normally open, and also causing the wiper relay to not be energized.
- Modify the plastic cover on the wiper motor so that you can mount a SPDT switch with a roller on it's lever that would ride the top of the gear or disc, and create some kind of raised area to trigger the switch on/off.
- Maybe use a latching relay? I haven't been able to see how it would function correctly yet.
- Maybe use a programmable solid state relay?
- Maybe create a new module to only run the wipers? Could also get intermittent back. Would there actually be interest in this? You could just keep GM5, and remove all of the other wires from it to achieve the same outcome...
- Maybe reuse a standalone wiper module from another car.

The wiper motor and park switch for reference and possible future brain storming:

So, as of right now as I finish typing this with all of the current issues and alternative methods from the diagram, which did I go with on my car? Well I still have a lot more work to do to the car and looking to have the car out on the track for the first time at a DE in March; I'm leaving this part of the wiring unfinished to be completed later if a better solution arises. If I was to complete the wiper wiring right now, I would go with the last diagram shown, possibly a solid state relay to be quieter, have pin 85 of the new relay off a separate fuse, install a SPST switch or button some where easily reached while belted in, to isolate the normally closed contact if needed.

Last edited by KTulay; 12-06-2014 at 12:59 PM.
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