E53 ABS Sensor Question

[Rockabilly Rebel]

If all 4 ABS sensors show the exact same speed while driving (Scanner on live data) - Does that mean that automatically they are fine to send info and run the ABS/DSC module?

Getting air gap code but speed from the sensor is fine and matches 3 others.

Getting no DSC signal to transfer case code.



Thanks

[andrewwynn]

If you are getting air gap code I would bet the computer though able to extract the correct wheel speed that based on the actual waveform knows that the sensor is at the wrong distance to the sensor ring in the wheel bearing.

If you know which wheel, I would work on some small adjustments to the position of the sensor before replacing e g. Shim the sensor out or sand off a little of the plastic so you can install farther in. First I would clean out the mounting hole with a wood rod and sandpaper then if the sensor isn't tight, wrap it with Teflon tape. There's a recent thread where somebody had nearly the same problem and just some Teflon tape solved the problem.

The sensors are stupid sensitive! A coating of rust on them is enough to through them off so clean them also. Lastly ensure the angle is perfect. There is very little tolerance to the mounting hole but if it's not straight out could cause the air gap alert.

[Rockabilly Rebel]

Originally Posted by andrewwynn

If you are getting air gap code I would bet the computer though able to extract the correct wheel speed that based on the actual waveform knows that the sensor is at the wrong distance to the sensor ring in the wheel bearing.

If you know which wheel, I would work on some small adjustments to the position of the sensor before replacing e g. Shim the sensor out or sand off a little of the plastic so you can install farther in. First I would clean out the mounting hole with a wood rod and sandpaper then if the sensor isn't tight, wrap it with Teflon tape. There's a recent thread where somebody had nearly the same problem and just some Teflon tape solved the problem.

The sensors are stupid sensitive! A coating of rust on them is enough to through them off so clean them also. Lastly ensure the angle is perfect. There is very little tolerance to the mounting hole but if it's not straight out could cause the air gap alert.

What if the CV axle collar ring was a fraction of a turn off from where it should be? Air gap?

[andrewwynn]

Here is an example of a good and an "air gap" waveform. When the square wave gets triangular enough you will get an error even if the waveform is tall enough to register a speed.

[andrewwynn]

Originally Posted by Rockabilly Rebel

What if the CV axle collar ring was a fraction of a turn off from where it should be? Air gap?

The only parts to the equation are the ring in the bearing and the position of the sensor. The sensing part of the sensor is on the side (flat part). As somebody mentioned you can damage the bearing ring which can cause a problem and it's conceivable that rust can get in there which you could theoretically remove with the likes of a q-tip with the sensor removed and turning the wheel.

Not sure what you mean by collar ring. The boot strap? No influence on the sensor.

When installing the bearing it's possible to get some rust in the way of fully seating the bearing and could cause the problem.

[Rockabilly Rebel]

Originally Posted by andrewwynn

The only parts to the equation are the ring in the bearing and the position of the sensor. The sensing part of the sensor is on the side (flat part). As somebody mentioned you can damage the bearing ring which can cause a problem and it's conceivable that rust can get in there which you could theoretically remove with the likes of a q-tip with the sensor removed and turning the wheel.

Not sure what you mean by collar ring. The boot strap? No influence on the sensor.

No, the ring that tightens the CV axle in place. It is a collar ring that needs to be torqued to 310ft/lbs. If it were a little loose, it might give that fraction of a space just big enough to cause the 'air gap'. What do you think?

[Rockabilly Rebel]

I think I found the solution to my air gap issue. The collar nut that hold the CV axle to the wheel hub needs to be torqued to 310ft./lbs. I thought it was spot on but kept getting this code. So I tightened just a touch more --> no more air gap code.

[andrewwynn]

The axle nut only pulls the Sandwich of the hub the bearing and the CV together it won't have much effect on the bearing cover but as I mentioned those sensors are a stupid sensitive.

The axle nut only affects the inner race it won't pull the outer race closer to the sensor. Keep us posted if the bug returns

[Rockabilly Rebel]

Yup, might be doing that.