Learn me BMW window motors!

Dear GRM,

I don't post a lot. I have a E36 M3ty E36M3 that I beat on a lot. Well, not lately. This year has been giving me fits with stupid stuff breaking in/at inopportune places/times. It's been... frustrating. That MF'er has spent more time on jacks this summer than tarmac.

Anyway, I've fixed 99% of the white board stuff needed to pass tech inspection and I really want to try and blow this thing up at an hpde in mid-october. Problem is there is one problem I simply cannot seem to fix- The windows don't work.

Here are things that I've done/tried/failed- - Replaced window switches - Replaced window motors - Replaced Comfort control module from a known working donor - Swapped every and any relay remotely close to proximity of the window controls with known relays from a friends operable car. - checked more wires with a multimeter than I have in my day job. Note- I'm an EE, which makes this issue especially... embarrassing. I have continuity and power going into the comfort control module, and I have connectivity from the module to the window motors, but I cannot for the life of me get power out of the module to the motors.

So my thoughts are to simply bypass the module and direct wire the switches to the motor. The issue lies in the E36 M3ty BMW wiring- 5 wires, 2 plugs, 1 ground, 2 power leads and 2 signal wires. I assume 12v power, but are the signal leads 12v as well? I'm just trying to wire this up to get my damn windows down for the track.

I'm up for ideas, even bypassing everything and making my own damn switches. I just need to ideally make the BMW motors work when I want them to work and in the direction that I desire.

Freaking BMW's.

I want to know whatever you find out. My E36 coupe's window would work most of the time, then some of the time, and now hasn't worked at all in months. Switch works, power everywhere, each individual component seems fine.

Are all parts specifically for your year of car? IE the control module, motor and switches? Mostly I'd be interested in making sure the control module that was known good was from the same year and also that it is from a car with the same number of doors. I've noticed that BMW will change things under the covers for parts that fit similarly, but end up having a different voltage requirement.

To solve your immediate issue, which is putting the window down for the track - just put 12v on the motor with a jumper wire to get them down if you can't solve it properly before you have to leave. I mean, ultimately, it's a DC 12v motor... as an EE you ought to be able to atleast make it go the right direction temporarily

Giant Purple Snorklewacker wrote: To solve your immediate issue, which is putting the window down for the track - just put 12v on the motor with a jumper wire to get them down if you can't solve it properly before you have to leave. I mean, ultimately, it's a DC 12v motor... as an EE you ought to be able to atleast make it go the right direction temporarily

Quoted for teh truths. I just use a cordless drill battery, hook it up and see where it goes. It's just 2 wires, with reversing polarity.

Giant Purple Snorklewacker wrote: To solve your immediate issue, which is putting the window down for the track - just put 12v on the motor with a jumper wire to get them down if you can't solve it properly before you have to leave. I mean, ultimately, it's a DC 12v motor... as an EE you ought to be able to atleast make it go the right direction temporarily

I know, but with door cards and the whole window motors buried inside... It's a pain. I'm looking to get an easy solution around that. I'm considering even just leaving bare jumper leads tethered under the dash and bringing a 12v power supply with me from work, haha.

Harvey wrote: Are all parts specifically for your year of car? IE the control module, motor and switches? Mostly I'd be interested in making sure the control module that was known good was from the same year and also that it is from a car with the same number of doors. I've noticed that BMW will change things under the covers for parts that fit similarly, but end up having a different voltage requirement.

The control module was from the exact same model year and factory spec- 97 M3c,5sp. Both modules had identical bmw part numbers on them, as well as colors/wire pinouts.

Why haven't you wired in a separate rocker switch->relay->motor setup? How many wires in/out of the motor itself? Have you gotten it to move the windows at all via hotwiring? Is there a built in relay w/in the motors themselves?

If you don't make the october track day, come down for a weekend in November for a rallyx. We've got two that month and you'll at least get some seat time

golfduke wrote:

Giant Purple Snorklewacker wrote: To solve your immediate issue, which is putting the window down for the track - just put 12v on the motor with a jumper wire to get them down if you can't solve it properly before you have to leave. I mean, ultimately, it's a DC 12v motor... as an EE you ought to be able to atleast make it go the right direction temporarily

I know, but with door cards and the whole window motors buried inside... It's a pain. I'm looking to get an easy solution around that. I'm considering even just leaving bare jumper leads tethered under the dash and bringing a 12v power supply with me from work, haha.

Harvey wrote: Are all parts specifically for your year of car? IE the control module, motor and switches? Mostly I'd be interested in making sure the control module that was known good was from the same year and also that it is from a car with the same number of doors. I've noticed that BMW will change things under the covers for parts that fit similarly, but end up having a different voltage requirement.

The control module was from the exact same model year and factory spec- 97 M3c,5sp. Both modules had identical bmw part numbers on them, as well as colors/wire pinouts.

Stupid question, but are any fuses or relays busted?

none that I could find, no. Everything looks to be in proper working condition.

Does it have a sunroof? If so, does the sunroof work? Did you try swapping the applicable fuse just for E36 M3s and giggles?

just out of curiosity.. are you using the right colour switches? the backside of BMW switches come in different colours. Yellow, White, and green (I think green?) and are not interchangeable

Harvey wrote: Does it have a sunroof? If so, does the sunroof work? Did you try swapping the applicable fuse just for E36 M3s and giggles?

It had a sunroof, but I deleted it with the interior. I still have a tigerprint headliner though!

mad_machine wrote: just out of curiosity.. are you using the right colour switches? the backside of BMW switches come in different colours. Yellow, White, and green (I think green?) and are not interchangeable

Yes, one yellow, one green for pass/drivers, the control modules were literally identical, right down to sticker placements.

Sometimes all the windows are on one circuit, perhaps deleting the sunroof is causing the problem? Like how some cars the windows won't operate unless all the switches are plugged in.

Once these things decend past mechanical into electrical gremlins I usually just wipe my hands of it and tell customers they need to go to the dealer.

the windows worked after the sunroof delete though...

I typically agree, but the car is well beyond the point of my dealer wanting to touch it, haha. It's a gutted 97 with 260k on it. They're a little more concerned with doing PDI's on New X series's than a ratty track car with a mysterious electrical gremlin.

Plus, I maintain that there is not a single E36 in existence that does not have something berkeleyed up electrically with it. I'll bet my house on it.

So just make your own window circuit. I would be looking at that option if it was my car.

OR, drill a hold in the door card right over the allen key manual override for the motor. Add fun handle on appropriate allen key.

I can't remember specifically, but I think mine have an allen key on the motor to turn it if necessary.

rcutclif wrote: OR, drill a hold in the door card right over the allen key manual override for the motor. Add fun handle on appropriate allen key. I can't remember specifically, but I think mine have an allen key on the motor to turn it if necessary.

whaaaaaaat?! Is this a thing?!

There's gotta be an electrical engineer joke in here somewhere.

Are you sure you don't have manual windows?

Trust me, not my proudest moment.

well, I know for a fact the sunroof has a manual override, like this:

I thought the windows had the same thing but after searching google images it seems I may be remembering wrong. Basically I thought the brass in the middle was an allen key. You just need to turn that shaft somehow if you can weld/tap/whatever something on there.

Window regulator:

This exploded diagram shows both a motor and a crank. Anyone know if the rest the same and he can just convert to crank?

In reply to bluej:

I've heard of this being done, but never done it myself. I also think the parts might be hard-ish to get since I don't think any US spec e36s had manual windows. maybe if you go to a dealer armed with a part number they can get it for you?

In reply to golfduke:

I haven't read all the responses, but if you head to the pick'n'pull and find a set of window switches from a 240 Volvo, you can bypass all the hoo-hah involved with the German electronics. I presume its a coupe, which means its got frameless windows, and switches on the door handles that drop the window a wee bit when you pull the handle, and closes it again when the door senses its closed... Something in that area will be broken. The Volvo switches need power, ground and wires to the motors.

Okay, so since this thread has had some minor interest as to my findings, here is what I've determined-

Cliffs- The comfort module is the issue, more in that there is some signal not being given to it preventing any 12v output.

So, after spending an entire weekend literally troubleshooting, I can find nothing wrong. I have power and signal going into the comfort module, and I can hotwire 12v to the window motors from the comfort relay outputs and get them to work. This shows me continuity and function both to and from the module. I know the module is good, so there has to be some sort of anti-theft/interlock signal that the module is not getting that is preventing the module from passing 12v and signal through to the windows. I am leaning toward it being a security signal, but I cannot find it for the life of me.

It turns out that there are 5 wires on the OE window motors. 2 are +/-12V (larger 2 pin plug), 2 are signal wires, and 1 is ground (smaller 3 pin plug). You need to tie in the 1 ground from the small plug to an actual ground, and then you can simply reverse polarity to operate the windows up/down. Ignore the rest, because apparently they don't matter.

Regardless, I now have functioning window motors with the switches. I simply bypassed the comfort module and re-ran wires direct from the switches themselves. What a pain in the gonads this thing is.

Now to sign up for track days.

Final Update- I have power windows again!

Apparently there's either something wonky with my car's grounding, because the only way my new switches work is if they are directly hooked to the (-) battery terminal as opposed to chassis ground.

Regardless, the motors and switches are installed on a completely new circuit. I chased all the wires and tidy'd everything up, as well as installed my fancy new brushed aluminum door cards so it doesn't look as ratty inside. The car is officially track ready, and I am happy.