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[ArtVandelay]

Hi, can someone please tell me exactly where my wheel speed/abs sensor is on my 07 335i? Im presuming they are in the wheel wells behind the wheel well liner, but would like to make sure... I've searched for posts and diagrams with no luck...

Also, has anyone changed one? Its seems like it'd be pretty simple, but just wondering...

Thanks

[ENINTY]

You are looking in the wrong place. The ABS/speed sensor is attached to the hub. Look for the wire that is attached to the strut and follow it to the wheel hub and you'll find the sensor. It is usually attached with an Allen bolt. Easy to replace. Keep in mind that on the right front and left rear wheels there are two wire harnesses, one for the speed sensor, the other for the brake wear sensor.

[orangedawg]

Also, the sensors may be behind the wheel well trim. IIRC, the sensor is attached to the hub, like ENINTY notes above. It is held on, I think, by a hex/star screw. Take it out and check to see if it is clean (I think it's a magnet, so clean it off). The wire then goes into a "holder/housing" behind the wheel well plastic. They are pretty easy to change, just be careful opening the blue "cover" that the wire attaches to behind the wheel well.

what makes you think you need a new sensor? Just curious.

See item 7 below for front:
http://www.realoem.com/bmw/showparts...94&hg=31&fg=10

See item 20 below for rear:
http://www.realoem.com/bmw/showparts...30&hg=33&fg=30

[ArtVandelay]

Originally Posted by ENINTY

You are looking in the wrong place. The ABS/speed sensor is attached to the hub. Look for the wire that is attached to the strut and follow it to the wheel hub and you'll find the sensor. It is usually attached with an Allen bolt. Easy to replace. Keep in mind that on the right front and left rear wheels there are two wire harnesses, one for the speed sensor, the other for the brake wear sensor.

ENINTY, I'll keep that in mind, that there are two sensors. Thanks

[ArtVandelay]

Originally Posted by orangedawg

Also, the sensors may be behind the wheel well trim. IIRC, the sensor is attached to the hub, like ENINTY notes above. It is held on, I think, by a hex/star screw. Take it out and check to see if it is clean (I think it's a magnet, so clean it off). The wire then goes into a "holder/housing" behind the wheel well plastic. They are pretty easy to change, just be careful opening the blue "cover" that the wire attaches to behind the wheel well.

what makes you think you need a new sensor? Just curious.

See item 7 below for front:
http://www.realoem.com/bmw/showparts...94&hg=31&fg=10

See item 20 below for rear:
http://www.realoem.com/bmw/showparts...30&hg=33&fg=30

I'm pretty sure that my passenger rear is bad or dirty, as my dealer said I needed a wheel bearing in that corner but Im not convinced as the bearing has no play, nor no sound whatsoever. From searching...with my errors, its seems more condusive with the abs sensor. My link below shows the errors...


http://www.e90post.com/forums/showthread.php?t=527109

I see that the dealer likes to replace both the bearing and the speed sensor when this happens, but it seems like throwing money in a whole given there is no sign of the bearing having any play etc, ya know?

And Im out of warranty so...

[ArtVandelay]

Originally Posted by orangedawg

Also, the sensors may be behind the wheel well trim. IIRC, the sensor is attached to the hub, like ENINTY notes above. It is held on, I think, by a hex/star screw. Take it out and check to see if it is clean (I think it's a magnet, so clean it off). The wire then goes into a "holder/housing" behind the wheel well plastic. They are pretty easy to change, just be careful opening the blue "cover" that the wire attaches to behind the wheel well.

what makes you think you need a new sensor? Just curious.

See item 7 below for front:
http://www.realoem.com/bmw/showparts...94&hg=31&fg=10

See item 20 below for rear:
http://www.realoem.com/bmw/showparts...30&hg=33&fg=30

Thanks for the realoem links Orange... I had looked on there, but just in the wrong places... Mighty cool of ya

[ENINTY]

Okay, you need to understand how the speed sensors work. They are called "hall effect transducers". In the hub there is a metallic metal toothed wheel. The hall effect transducer reads the peaks and vallies if the toothed wheel and provides a signal that is translated into speed. The hall effect transducer has a magnet in it that reacts to the difference in magnetic pull between the peak (more metal mass) and valley (less metal mass) to create the signal. If the sensor goes bad, which it can, then it will not provide a signal.

[ArtVandelay]

Originally Posted by ENINTY

Okay, you need to understand how the speed sensors work. They are called "hall effect transducers". In the hub there is a metallic metal toothed wheel. The hall effect transducer reads the peaks and vallies if the toothed wheel and provides a signal that is translated into speed. The hall effect transducer has a magnet in it that reacts to the difference in magnetic pull between the peak (more metal mass) and valley (less metal mass) to create the signal. If the sensor goes bad, which it can, then it will not provide a signal.

Understood, thanks for explaining it to me. So are you in agreement with me?

I'm looking at a wheel speed sensor issue rather than a bearing issue, right?

[ArtVandelay]

Originally Posted by orangedawg

Also, the sensors may be behind the wheel well trim. IIRC, the sensor is attached to the hub, like ENINTY notes above. It is held on, I think, by a hex/star screw. Take it out and check to see if it is clean (I think it's a magnet, so clean it off). The wire then goes into a "holder/housing" behind the wheel well plastic. They are pretty easy to change, just be careful opening the blue "cover" that the wire attaches to behind the wheel well.

what makes you think you need a new sensor? Just curious.

See item 7 below for front:
http://www.realoem.com/bmw/showparts...94&hg=31&fg=10

See item 20 below for rear:
http://www.realoem.com/bmw/showparts...30&hg=33&fg=30

Also, here's the code that popped up.. But that means rear drivers, correct?

[ENINTY]

Originally Posted by ArtVandelay

Understood, thanks for explaining it to me. So are you in agreement with me?

I'm looking at a wheel speed sensor issue rather than a bearing issue, right?

I agree with you. It's rare for a wheel bearing to go bad without some provocation such as hitting a curb or hitting a very sharp pothole (both instances would carry other damage with it like a damaged wheel or suspension component), or unless the car has serious miles on it say on the order of 200K. I would think the wheel bearing would have to be is such a degraded condition to cause the speed sensor to not properly track the toothed wheel that you'd definately notice the bad bearing. Since you have no other indication such as noise at the bearing starting with replacement of the wheel speed sensor is the most logical choice.

Your other post indicates the symptom is intermittent, which to me makes sense that it is the wheel speed sensor (it has probably lost its hermetic seal and gets wet and doesn't work, then dries out and starts to work again). The part is called "pulse generator" P/N 34526760425. Tischer sells it for $75.

You will have to partially remove the inner fender line to get to the connector to remove the sensor wire harness.

[orangedawg]

You can check to see if your speed sensor is bad by putting a multimeter on it. What I did was disconnect the the electrical connector at the ABS computer. It's located under the hood, on the driver's side, and will have the brake lines going into it. Disconnect the eletrical connector. What you want to do is get a reading from each of you wheel speed sensors and see if they read differently from each other.

I post below the pinouts for the e90's at the abs connector (located under the hood as I noted in my above post). Put a multimeter with really thin wire (20 gauge or so) to the pins on the connector to test the sensors. You want to use the diode setting on your multimeter. Again, the below link has tons of diagnsotic stuff, way more than most people will ever do. The basic advice on that forum is after checking wheel speed sensors, if they test good, is to send unit to get it repaired. The only place I found that will do our model (e90 with xi) is module masters in Idaho for $300.

BTW, that forum is very long, over 13 pages of long posts. Super informative, though. I think I started posting my info on page 9, I think.

Pin out:
I've got an 07 e90 328xi and was trying this out. From what I found in Bentley's, it looks like these are the pin outs for my car:

RF 6 and 18
LF 21 and 22
RR 19 and 31
LR 20 and 33

Link to ABS/DSC error forum:
http://www.bimmerfest.com/forums/sho...d.php?t=356272

[ArtVandelay]

Originally Posted by orangedawg

You can check to see if your speed sensor is bad by putting a multimeter on it. What I did was disconnect the the electrical connector at the ABS computer. It's located under the hood, on the driver's side, and will have the brake lines going into it. Disconnect the eletrical connector. What you want to do is get a reading from each of you wheel speed sensors and see if they read differently from each other.

I post below the pinouts for the e90's at the abs connector (located under the hood as I noted in my above post). Put a multimeter with really thin wire (20 gauge or so) to the pins on the connector to test the sensors. You want to use the diode setting on your multimeter. Again, the below link has tons of diagnsotic stuff, way more than most people will ever do. The basic advice on that forum is after checking wheel speed sensors, if they test good, is to send unit to get it repaired. The only place I found that will do our model (e90 with xi) is module masters in Idaho for $300.

BTW, that forum is very long, over 13 pages of long posts. Super informative, though. I think I started posting my info on page 9, I think.

Pin out:
I've got an 07 e90 328xi and was trying this out. From what I found in Bentley's, it looks like these are the pin outs for my car:

RF 6 and 18
LF 21 and 22
RR 19 and 31
LR 20 and 33

Link to ABS/DSC error forum:
http://www.bimmerfest.com/forums/sho...d.php?t=356272

Thanks bro. I'm gonna give it a try. Hey, that link is dead...

[ArtVandelay]

Originally Posted by orangedawg

You can check to see if your speed sensor is bad by putting a multimeter on it. What I did was disconnect the the electrical connector at the ABS computer. It's located under the hood, on the driver's side, and will have the brake lines going into it. Disconnect the eletrical connector. What you want to do is get a reading from each of you wheel speed sensors and see if they read differently from each other.

I post below the pinouts for the e90's at the abs connector (located under the hood as I noted in my above post). Put a multimeter with really thin wire (20 gauge or so) to the pins on the connector to test the sensors. You want to use the diode setting on your multimeter. Again, the below link has tons of diagnsotic stuff, way more than most people will ever do. The basic advice on that forum is after checking wheel speed sensors, if they test good, is to send unit to get it repaired. The only place I found that will do our model (e90 with xi) is module masters in Idaho for $300.

BTW, that forum is very long, over 13 pages of long posts. Super informative, though. I think I started posting my info on page 9, I think.

Pin out:
I've got an 07 e90 328xi and was trying this out. From what I found in Bentley's, it looks like these are the pin outs for my car:

RF 6 and 18
LF 21 and 22
RR 19 and 31
LR 20 and 33

Link to ABS/DSC error forum:
http://www.bimmerfest.com/forums/sho...d.php?t=356272

Sorry if this is elementary man, but I've never really done any type of electrical diagnostics. Basically youre saying that I dont even need to mess around with them under the car, that I can turn the car on, unplug that harness and test those corresponding pins?

And Ive searched for the forum you posted the broken link to but cant find the exact one.

Thanks again for your help.

[orangedawg]

You do not go under car to read the sensors. Don't turn on car. Go under hood. Go to driver's side, near firewall. Next to the cabin filter (it's under that long cover below your wipers) is another squarish looking box with a cover on it on the driver's side. Open it. You should see the brake fluid reservoir and the ABS/DSC module (will have a bunch of brake lines going into it).

Take off electrical connector from ABS (I think you pull up on the coonecotr and then slide it, but can't recall exactly off the top of my head. Once connector off, look at end of connector. You will see about 40 pin-outs. Get a multimeter. Set it to diode setting. Take some real thin wire and place it in the pinouts I noted above. Attach ends of multimeter to those wires. Read multimeter dislay. note the value. Reverse the leads and read again. Note the reading. Go onto the next set of pinouts. Repeat until all read. If the values are not close in value to each other per sensor, you have a bad sensor. DO NOT turn on car when you are doing this. Having car on does nothing, as when you remove the connector, there is no power going to the sensors. You are looking to see if the readings are the same.

Didn't I already provide a correct link and pages and posts in another thread of your recently? Or was that someone else?

[orangedawg]

Here's my reply in your other thread. Maybe you can merge the two threads/posts so you don't get answers in both threads for same questions.


Okay, here's a working link (at least it works for me):
http://www.bimmerfest.com/forums/sho...d.php?t=356272

See post:
#24 about location of sensors
#30 about the location of the abs (pic is a e39, but ours is same location on the driver side)
#48 has all the info you need to check out ABS/DSC, sensors, how to test, and tons of info
#234 my post about e90 pin-outs.
RF 6 and 18
LF 21 and 22
RR 19 and 31
LR 20 and 33

BTW, I posted my readings using 3 different multimeters and all were different, but each multimeter gave similar results amongst itself. What you are looking for is similar numbers across all 4 sensors. And although each multimeter gave different readings, my sensors are fine and work properly.

[ArtVandelay]

Very, very cool of ya orange.. Thanks for taking the time. I'll make sure to let ya know how I make out and post it here as to help people in the future as well.

[notanotherbmw]

I went to replace my brake sensor and the speed sensor is there, but the brake sensor plug is not there (in the black box). Instead, the wire runs down under the suspension and plugs into a plug. Could this have been rewired for some reason? Could the brake sensor be on the opposite side? (Im not going through all that again without being 100% sure) lol.

Also, the brake sensor would not clip into the caliper. Could the previous owner have replaced with an OEM caliper? Or just the wrong side? It seems strange that the speed sensor is on this side, and there is room in the box for the brake sensor.

[Lotus99]

Originally Posted by ENINTY

Your other post indicates the symptom is intermittent, which to me makes sense that it is the wheel speed sensor (it has probably lost its hermetic seal and gets wet and doesn't work, then dries out and starts to work again). The part is called "pulse generator" P/N 34526760425. Tischer sells it for $75.

PS Make sure you check on realoem first to see which part # applies to your car. The one above, does NOT apply to 335's:

http://www.realoem.com/bmw/enUS/part...&q=34526760425

Part 34526870077 is what you'd be looking for in that case.