Just cracking open my 1993 K75 project bike, and I need some help decyphering the ABS wiring (there doesn't seem to be anything in the wiring diagram or shop manual about ABS). 

The previous owner seems to have disconnected the ABS (which is fine, I don't need it), but this thing was in the panniers:
 

...and there seems to be a matching connector / cable bundle tucked away in the tail-end storage compartment. Is this the ABS control unit? Is there a wiring diagram or shop manual somewhere for the K75 ABS?

And if it's *not* the ABS unit, then what's the connector in the "trunk" for?

Go to a website such as www.realoem.com/bmw and type in the last seven digits of the BMW part number which is stamped onto the part, in this case 1 459 699, and you'll see that it is the ABS control module as you guessed. Does the plug fit it? There you go.

The Google Gods will tell you a lot about BMW wiring diagrammes if you give it a healthy search, with images, in most cases. Also, try the forum's search engine on the 'Portal' page.

Yes, that is the ABS "brain".  It is mounted in the tail cowl on the first generation ABS(ABS1).  

As far as wiring diagrams, if you have a Clymer shop manual, you will find them on pages 716 and 717.

Two Wheels Better wrote:Go to a website such as www.realoem.com/bmw and type in the last seven digits of the BMW part number which is stamped onto the part, in this case 1 459 699, and you'll see that it is the ABS control module as you guessed. Does the plug fit it? There you go.

The Google Gods will tell you a lot about BMW wiring diagrammes if you give it a healthy search, with images, in most cases. Also, try the forum's search engine on the 'Portal' page.

Thanks, TWB. I've done all of that. Like I mentioned, the K75 wiring diagram from the tech page makes no mention of ABS. Realoem also doesn't seem to have it (I was searching by my bike model, instead of by part number!), neither does the [url=https://www.kforum-tech.com/Manuals/BMW Manual K75-K100 2-Valve.pdf]shop manual[/url] (although it mentions looking at the K1100 manual for ABS1.).

BUT, I did google the part number off the mystery box, and it is indeed the ABS unit, which is all I need to know. Thanks!

Point-Seven-five wrote:Yes, that is the ABS "brain".  It is mounted in the tail cowl on the first generation ABS(ABS1).  

As far as wiring diagrams, if you have a Clymer shop manual, you will find them on pages 716 and 717.

Excellent, thanks! My Clymer's is still in the mail, so I'll check it out when it gets here.

Should you want to remove the wiring, it's not that bad of a job if you do it as part of a frame up rebuild of the bike.

The ABS wiring is pretty independent of the rest of the bike's wiring, and as such, if you are willing to unwrap the harness, remove the ABS wiring, and rewrap the harness, it is a fairly straightforward task that can be done in an afternoon or two without a lot of mental effort.

I did it on one of my bikes as part of cleaning up the connectors, etc. Was pretty easy.

Removing the ABS will make removing the rear mudguard to allow wheel removal a lot easier.

Two Wheels Better wrote:The Google Gods will tell you a lot about BMW wiring diagrammes if you give it a healthy search, with images, in most cases. Also, try the forum's search engine on the 'Portal' page.

roach374 wrote:Thanks, TWB. I've done all of that.

Not quite all of that, at least with regard to Google god worship.    Resources abound.
There's an ABS overview manual in the link at the bottom of this post.
The ABS component wiring is depicted in a wiring diagram in the link at the bottom of this post.
There's a concise description of the system at this site.

Plus, there might be valuable prizes available for those who collect the whole set because there's more out there.

Laitch wrote:

Two Wheels Better wrote:The Google Gods will tell you a lot about BMW wiring diagrammes if you give it a healthy search, with images, in most cases. Also, try the forum's search engine on the 'Portal' page.

roach374 wrote:Thanks, TWB. I've done all of that.

Not quite all of that, at least with regard to Google god worship.    Resources abound.
There's an ABS overview manual in the link at the bottom of this post.
The ABS component wiring is depicted in a wiring diagram in the link at the bottom of this post.
There's a concise description of the system at this site.

Plus, there might be valuable prizes available for those who collect the whole set because there's more out there.

Great stuff, Laitch, thanks!

good luck man, you're a bolder person than me

Test question for all the ABS experts (I do have the correct answer).

How many wheel sensor pulses are required before the system is activated

A. 50
B. 150
C. 250
D. 500

No prizes for this one.