Brake Lining Code... Can't Figure It Out?!

[Triton540i]

Hey Everyone...

So I fixed the situation with my rear suspension, but after doing some work on my car, I threw a code for brake linings? I went back and checked the sensors in both the rear and front wheels and the pads have plenty of pad left. I then took both sensors out, cleaned them and reinstalled them. I made sure all the connections were tight and clean, but I still get a sensor problem?

I'm wondering if this is a closed loop system or an open system? Do you get a code if you unplug the sensor? If I take an Ohm meter to the actual sensor and run it across both leads, is it going to give me a closed loop reading or is it open? I'm guessing the actual sensor will ground out to the rotor when the pads get to their wear point, does that mean that this makes the connection between both leads in the sensor and that closes the loop?

I guess I could go through the wiring schematic in the Bentley, but thought I would ask one of you if you knew how this thing works?

One more thing... on the passenger side of the car, there is a great place to put your jack stands, one of the only places that I would consider "safe" other than the actual rails. If you're experienced in working on your car, you know the place I'm talking about... next to the little dogbone part of the suspension, but on the subframe part. Anyway... there are a couple wires that go beside that and while I was quickly using it as a jacking area, I used a small block of wood there and may have (could have) pinched a wire there... is that the extended wires from the brake sensor circuit?

I'm kind of wondering if you were to unplug both sensors, it wouldn't throw a code, but maybe it's the other way around?

I've given many possible combinations to my problem, do you have any input as to diagnose this code problem?

Thanks for the help! :)

-Eric

P.S: I just read my posting and I sound retarded... it must be the Newcastle talking. ;)

[ILoveMPower]

I have the same problem, my pads and sensors are fine but it still throws the brake linings code every time I drive.

The reality is, the wire's grounding out SOMEWHERE... so your best bet is to follow the wires back and see if something isn't right.

I'm no expert but this is what I got out of the situation, hope this helps.

[Karl]

Brake sensor system is a closed loop so if you unplug the sensor it will give you the warning. So if one of the connector plugs is loose or crudded up you'll get a warning. wearing the sensor against the brake rotor wears through a thin copper strip to open the circuit.
But the system will also give you a warning if it gets grounded, like the sensor worn down to the rotor, or any other of the million other places a wire can chafe thru the insulation. Start by seeing if there's some slack in the wire around the strut.

[buddyglassjr]

...with the hood up, on the driver's side, there's a wrapped bunch of wires that go into the bottom of the fuse box right at the firewall. I followed that down to where the loom ended, started unwrapping and found the light brown wire that I had traced (after 5 weekends of head bashing, probing, prodding, plugging, unplugging, etc.) wrapped in a really bad "twist and solder" connection, conveniently hidden behind what looks like it should have been a small vacuum cap (and not the heat shrink cap that it apparently was.)

The connection was still good but condensation had pooled inside the cap and it was green (like fake gold). I cut that section out, resoldered it myself, and have been driving "brake lining warning message"-free for 6 months. (The best part is when I explained how I did it to my friend - the previous owner of the car who had been driving around with the "brake lining" message for over 4 years.)

Anyway, the reason I say check there? I happened to check out a few other junkyard 5's that had the same corroded connection hidden deep inside the wire loom - a place that I've never seen mentioned in any of the "help with brake linings message" posts.

$0.02. Pics of said wire/loom can be posted if anyone's interested.

[ILoveMPower]

$0.02. Pics of said wire/loom can be posted if anyone's interested.

This would be much appreciated! :)

[buddyglassjr]

This would be much appreciated! :)
http://i105.photobucket.com/albums/m204/buddyglassjr/IMAGE_00006.jpg

Okay, I lied - it wasn't a brown wire. And sorry for the crap phone-cam pics.

If I remember correctly, it was a blk/yel and red wire wrapped in black (coming straight out of the wheel well hole where the brake lining wire enters the engine bay from the wheel well.) From there it went up to the rusty connection contraption and into the yellow wire (which is actually part of the in/out loop of the brake lining system.) If someone can take a picture of the wires unmodified in this section, I can tell you which ones they are. That, or I'll check the next time I'm at the junkyard.
http://i105.photobucket.com/albums/m204/buddyglassjr/IMAGE_00007.jpg

Soon after I did the hack, the brake lining sensor really did go out so I simply connected the in/out loop at the yellow wire (bypassing the entire brake lining sensor system.) And, yes, I'm aware of the "consequences" of bypassing the system - connect these wires at your own risk (with the full understanding that your BMW will no longer be able to tell you, much like most of the other cars on the road today, that it's almost time to change your brake pads.)

Hope these help somebody.