ESP light and lateral acceleration sensor

Hi all
I have a 2008 313 2.3 diesel. It has the ESP light come on after a few minutes of driving. I've had it plugged in and it comes up as 'lateral acceleration sensor'. I've read online that it is under the drivers seat. It's £80-£120 new. In terms of a used genuine one, does anyone know if the codes are the same on them all? or if there are various part numbers and I need to remove the seat etc to check it? Also, am i right in saying that it should just be able to be plug and play? no need for a further diagnostic plug in to clear light?

Many thanks in advance

If this laternal acceleration sensor/relay was mounted on an angle to allow for the replacement swivel seat,might the change of positioning be the cause of the issue?

Bigyellow said:

If this laternal acceleration sensor/relay was mounted on an angle to allow for the replacement swivel seat,might the change of positioning be the cause of the issue?

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I'm curious to know the answer to your question, and I can only speculate why mounting your sensor at an angle might have an effect upon it.

I work with a high school robotics teams that uses a Bosch Inertial Measurement Unit (IMU) for determining orientation and positioning for robots. The ones that we use are 3-axis devices, so they are constantly monitoring acceleration along the x, y, and z axes.

Our robotics sensors must be installed with the device level to the plane of constant gravitational acceleration IF we expect the z-axis acceleration to be a constant 1 g and the other two axes to be 0 g when the robot is resting level on the floor. Any tilt in the mounting will lower the z-axis acceleration from 1 g and increase the acceleration on each axis that is not in the plane of constant gravitational acceleration (due to the tilt) when the robot is at rest, and cause readings while the robot is in motion to be different than expected/desired.

The van system must have some allowance for the van not being level, however, as vehicles are often parked on hills that may alter pitch as well as roll, and they drive in similar situations. So while it seems like there MUST be some effect from mounting the sensor in an orientation different than its original orientation, its not immediately obvious what effect a minor change would have, or whether a tilt around one axis would have more affect than a tilt around another.

Bigyellow said:

Hi all
It has the ESP light come on after a few minutes of driving. I've had it plugged in and it comes up as 'lateral acceleration sensor'.

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Quote from Wiki... "Lateral acceleration is acceleration to the side"

So my take is that the ESP system is looking at Lat Acc and comparing this to steering input (from steering angle sensor) and constantly checking whether everything is OK or not, ie if the vehicle is travelling sideways (Lat Acc not Zero) and no steering input then the vehicle could be skidding. The system also monitors individual wheel speeds so this may be worth checking as well.

So if after driving for a few minutes Lat Acc does not match steering input or wheel speeds then on goes the warning light.

Try monitoring Live Data for Steering Angle Sensor, Lat Acc and all wheels speeds and see if you can spot any anomaly, ie SAS never at Zero or Lat Acc never at Zero or oddball wheel speeds.

Keith.

Hi Keith. How would I go about testing these measurements? Would it have to be STAR diagnostic tool?
So from you say,it's likely to be a mounting angle issue?

Bigyellow said:

Hi Keith. How would I go about testing these measurements? Would it have to be STAR diagnostic tool?
So from you say,it's likely to be a mounting angle issue?

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Yes STAR would do it, but so would something like an Autel MD802 or MD808, or likely the iCarSoft scanner mentioned in the Scanners section of the forum.

I doubt it is the mounting angle of the Lat Acc sensor but more likely mis-matched data coming back from one of the sensors I mentioned above.

Question, has this van always had this problem or did it suddenly occur? And if the latter what where the events leading up to it, ie did it have a wheel change or brake service, etc???

Keith.

The light coming on coincided with changing the front seat and moving the location of the sensor. A rear wheel was also changed. What difference would this make and how do I rectify it?

Bigyellow said:

The light coming on coincided with changing the front seat and moving the location of the sensor. A rear wheel was also changed. What difference would this make and how do I rectify it?

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OK So you made two changes when the light came on! We need to identify which one was the culprit.

The easiest to check will be the rear wheel speed sensor but you will need a scanner to do this. If you don't have one see if you can borrow one from a parts store or local repair shop. View live data for rear wheel speeds and drive down the road, they should both read the same, if not suspect the side that you changed the wheel as you may have damaged the wiring or disturbed the sensor.

If both wheel speeds are OK then look for live data from the Lat Acc sensor and see if this is plausible. You may have to try temporarily remounting it as near as possible to original to see what happens.

Keith.

PS You did correctly plug the wiring back into the sensor after moving it didn't you? Try unplugging and re-plugging to be certain.

PPS Please can you describe or post photos of the difference in mounting location for the Lat Acc sensor.

So was the issue resolved?

Kmyrkle said:

So was the issue resolved?

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The OP @Bigyellow was "Last seen Apr 14, 2019" so I doubt you will get an answer.

Try posting a new thread detailing your specific problem.

Keith.