Lateral acceleration sensor failure

[rf900rkw]

Or consult the oracle, ETM.





B74 - lateral accel sensor, accel sensor

B75 - yaw sensor, rotation sensor

[328 Power 04]

I've seen that picture, and it would have been great if INPA actually referred to one of those by name (or at least put the sensor name B74 in the description).


Problem for me is threads like this one here http://www.bimmerfest.com/forums/sho...d.php?t=765158
they say that it is the black one .. So it added to the confusion.


Also confusing is that the B75 sensor is mounted perpendicularly (left to right) in Z3, but parallel (front to back) in E46s. In my convoluted mind, I figured these are accelerometers that measure forces in which orientation they are placed. But maybe it's not the case.


I will replace that one (B74) and report back. Thanks

[rf900rkw]

The yaw sensor measures spin, relative vs absolute acceleration. As long as it's mounted in the same orientation to the horizontal plane, fore-aft vs left-right won't matter.

[E.Hands]

Subscribed for conclusion. Thanks guys :-)

[Randy Forbes]

According to the locals down here, the (U-Pullit's) front desk will loan you a charged battery & wheelbarrow for just the scenario you're talking about.

Alternatively, something like a motorcycle or riding lawnmower battery would be adequate to move the seat a few times, and not break your back in the process.

I would expect these replacement units need to be told to go back to work in their new home, and not just start working automatically after X# of miles__but who knows; maybe Johnny Government Car Designer created that dictum too?!?!

[328 Power 04]

According to the locals down here, the (U-Pullit's) front desk will loan you a charged battery & wheelbarrow for just the scenario you're talking about.

Alternatively, something like a motorcycle or riding lawnmower battery would be adequate to move the seat a few times, and not break your back in the process.

I would expect these replacement units need to be told to go back to work in their new home, and not just start working automatically after X# of miles__but who knows; maybe Johnny Government Car Designer created that dictum too?!?!

Oh I can command the replacement units to do things alright. I'm armed with 10+ cables and interfaces and old and new computers for it. No gubbimint telling my car how to behave & what I can do with it...


Problem (or not so problem) is that the 'U-Pullit' place is a family friend's repair shop with a lot of parts cars that I can roam around and pull parts for many past (diagnosing, coding, programming) favors. There is an E36 323is that should have that correct sensor, so I will try that one. I'll bring jumper cables next time. I didn't give up yet,... it was just too hot yesterday after fighting with wet carpet and a halfway connected seat. Good idea.

[328 Power 04]

Ok, here comes an update.


I acquired one of those acceleration sensors, and tried to put it on, but it was different, in the bracket and in orientation.
The sensor CAN be pulled out of the bracket, but I decided to plug it in and read sensor data with a diagnosing program first.

Data reading:
Sensor from a different car (I think E65) reads 0.5g when oriented in the same way as the stock Z3.

Original Z3 lateral acceleration sensor (with errors) read -0.14g when mounted to the car, on level ground. This is probably why it was sending an error. This needs to be 0.0g or thereabouts.





So I tried something different... I tried to run the adjustment procedure on the E65 sensor. It would not correct. Still read 0.5g... this sensor is oriented differently on E65 and can't be used.

So for fun, I ran the adjustment procedure (calibration) on the original Z3 lateral acceleration sensor. It successfully completed adjustment and now it reads -0.01g on level ground. I cleared the DSC error, and it remained off.

Calibration fixed my issue without buying a new sensor.




Also, FYI, you do not HAVE to pull the seat out, just undo the nuts and bolts, and raise it enough to lift the front carpet up. Access to the sensor is fine.

[HeliHover]

Great info.

I have a dsc light on too. I found a guy in Vancouver who will read my codes for 20 bucks whom I'll probaly be visiting soon. I have a feeling it is one of the two sensors under the seat. Are you able to recalibrate both sensors or just the one? And this was all done on INPA?

[328 Power 04]

I did error reading\clearing in INPA only.

I just went outside and checked INPA for the lateral acceleration sensor calibration, and it does not do it (it is a more advanced function). I used Rheingold ISTA with the same INPA interface. DIS may do it too, but I don't like DIS, so I avoid it. I didn't see\check for any calibration for the yaw (rotation) sensor.

If all you have access to is INPA, use it to read the codes first, because there may be so many factors why the system has errors.


Mine remained error free for now.

[HeliHover]

Ok so I was chatting with this guy some more. He has ista, and all the others, but no 20 pin. Are you doing this through the 20 pin?

[328 Power 04]

Yes, all modules on DSC Z3s read perfectly with the USB VAG KKL cable and 20 pin adapter on INPA and ISTA.
So basically all 1999+ non M Z3 will work flawlessly. Also flawless operation with 2001+ Z3M.


(Additionally I hooked up ISTA with the 20pin on my 99 M Coupe and I could read all modules except KOMBI (instrument cluster) with the USB KKL cable.)

[HeliHover]

ok Thanks!

I think I'll pass on this guy. This is the second person advertising saying they can "do it all", but do not have the 20 pin connector.

I just need to break down and get the damn software and figure this stuff out on my own and with you guys.

[steve f]

Okay, reviving an old thread.

I also have the DSC/BRAKE indicator lamps showing yellow. Checking the codes, I originally had a code for the lateral acceleration sensor and steering angle sensor. I was able to clear the steering angle sensor code, but not the lateral acceleration sensor code. I cleaned the connections, but was still unable to clear the code.

Then I replaced the lateral acceleration sensor with new, but the code still persists.

Any ideas, what is the next step?

[328 Power 04]

You have to calibrate the replacement lateral acceleration sensor.

- - - Updated - - -

If you are using my software pack, or any other INPA pack, I put instructions here http://www.bimmerforums.com/forum/sh...9#post29437829
and a few posts after will show what you may run into.

[steve f]

I'm not very computer savvy, so my eyes just glazed over a bit.

I am using a Schwaben scanner to read and clear codes. I'll need to study to see if it has this capability. If not then I'll need to see if I can get my old computer back up and communicating with DIS. Maybe I'll need to follow your instructions and get IPNA up.

[steve f]

update, success!!!

I was able to use the service function on my Schwaben scanner to calibrate the new sensor. I was able to erase the code and the DSC/BRAKE warning lamps are out. I'm going to wait until some of the ice at the end of my driveway thaws to go for a test drive.

Thank you again!!

[chilipeppermani]

This is a very good thread for me to monitor and learn and ask questions about as my floor pans got watersoaked and of course these sensors lie there in puddles in my 2001 Z3 2.5.

Hoping no damage occurred but will know once I get the water pump and engine work done and start the car up again. Keeping fingers crossed the many sensors aren't jacked up from H2O

- - - Updated - - -

Or consult the oracle, ETM.





B74 - lateral accel sensor, accel sensor

B75 - yaw sensor, rotation sensor

Thanks for posting this. I still can't figure out why BMW didn't put this kind of stuff in waterproof boxes in their cars without sealed hard tops. Just saying...

[Dakar Ole]

My feeling is they fail from old age as well. Connectors and bodies are quite waterproofed.

[chilipeppermani]

My day will consist of removing my interior to get my carpets fully out and process along the water removal. I will shop vac and blow dry the floor as I wait for water pump and pulleys etc. It will be a good time to disconnect all sensors and dry them out and put some dialectric grease in there before I get to my engine testing and cooling system repairs.
Water pump shaft wobbled loose and pulley broke,,,,, etc etc etc.

PS. Anyone know any promo codes for Bav Auto as I get ready to place my order for water pump etc? Thanks

[Dakar Ole]

BTW my last month's replacement did not require calibration-only about 75 miles of driving normally. And no visible water effects on the old one.

[Randy Forbes]

This is a very good thread for me to monitor and learn and ask questions about as my floor pans got watersoaked and of course these sensors lie there in puddles in my 2001 Z3 2.5.

Hoping no damage occurred but will know once I get the water pump and engine work done and start the car up again. Keeping fingers crossed the many sensors aren't jacked up from H2O

- - - Updated - - -





Thanks for posting this. I still can't figure out why BMW didn't put this kind of stuff in waterproof boxes in their cars without sealed hard tops. Just saying...

Worst ones I've yet seen__in fact the only ones I've ever needed to diagnose and replace__were in an M Coupe. Just saying...

[chilipeppermani]

Worst ones I've yet seen__in fact the only ones I've ever needed to diagnose and replace__were in an M Coupe. Just saying...

Being fairly new to BMW's I am pretty sure what an M coupe is so are you saying they were the worst from failures, or from getting water logged? I do know, my Z3 reminded me of Tom Cruises Porsche 928 in Risky Business. Not quite that bad, but wet enough to shop vac around the floor pan and carpets and foam under carpets once I found standing water on passenger side floor on top of the carpet.

[chilipeppermani]

I managed to get my center console out today and was glad I took the time to do so.
All seemed ok despite the carpet being wet and my efforts of drying it out, I removed the rear section of carpet and found a mouse nest of car insulation from another car of mine.
Once I got the nest out, I saw chewed wires in the power top switch area. I noticed at least 4 that were chewed bare for about 2.5 inches of each one. However, these go to a non used plug connector that I surmise would go to another switch if there was one next to the top opening switch.

With further eyeing of the top switch wires, I see maybe 2 of them with maybe a very slight 1/4 inch hint of chewing. Having found this, I am so glad I did the console removal.