4x4/DSC inactive

[grachal]

Hello,

About a year ago, I had the DSC/4x4 inactive message for the first time on my X5. This was sporadic every few weeks. I installed a new transfer case servomotor plasticgear back then. However the gear was fine and therefore did not solve my problem. I then just left it at that because the car drove normally, even when the message/lights popped up after driving a few meters.


In the last few weeks I've noticed more and more that on loose surfaces (e.g. my gravel driveway) the ABS on the front wheels kicks in briefly and lightly without me even stepping on the brakes.

Since last week it has been the case that when accelerating harder, especially out of right-hand turns, the right rear wheel starts to jerk/hop and feels like it is getting slip. The car also only seems to pull soley at the rear end. Even tho I had the 4x4 inactive warning, in the past the car seemed to still have 4x4


Then I suspected the ABS sensors/rings. I've now looked into Inpa a bit and followed the live data, wheel speeds are OK, but the front left wheel speed sensor is stored in the error memory, air gap too large.



The main problem seems to be the steering angle sensor. When I switch on the ignition it returns completely normal values, even if I steer back and forth while stationary. But as soon as I drove a few meters, the Inpa analog display suddenly jumps to zero and moments later the "DSC Christmas tree" appears in the instrument cluster. Inpa also says "5EB1 steering angle sensor... steering wheel center position unknown...



Calibration/zeroing didn't help.



But is the steering angle sensor really defective? Why does it work when car is stationary?

[andrewwynn]

If the inactive warning on you definitely dont have 4wd. The car reverts to RWD every time you are at a stand still and engages the front axle when after launch.

Abs kicking in as about to stop is a symptom of a dirty/loose/failing wheel speed sensor (which alone will disable DSC)

On my e53 one of the bolts for WSS sheared off and I just used wraps of Teflon tape to keep it tight. When weather got warmer it got loose and I had symptoms like you describe.

SAS not working is often the clock spring but dirty signal symptom of bad sas. (if the value jumps around).

Read the wheel speeds while doing figure 8 and all speeds see if you can find one that is intermittent that's the usual fail point.

DSC requires SAS so SAS problem will disable DSC and likely abs.

[Clavurion]

Originally Posted by andrewwynn

SAS not working is often the clock spring but dirty signal symptom of bad sas. (if the value jumps around).

On E53 steering angle sensor is lower on the steering column, nothing to do with clock spring.

[andrewwynn]

That's true nice catch


Sent from my iPhone using Tapatalk Pro

[grounch]

Also had a SAS issue, the 4x4 light was always on, but the "DSC 4x4 off" message was appearing after driving a bit.
After replacing and calibrating never had any 4x4 issue again. Quite easy job with some patience and the usual plastic stuff removal.

[grachal]

Thanks for your thoughts.
last week I wanted to replace the front left ABS sensor, but I got the wrong part, so I had to put the old one back in. Did some rust cleaning on the hub and sensor itself. That has affected the DSC/4x4 message and brake/abs lights, they are gone since then.

But the DSC light in the middle and the wheel hop remained. I also switched to another wheel set, just to be safe as I ran some big All Terrains (but never had any issues with that).


So I think my best bet is to get the SAS replaced, coded and recalibrated. Or if its possible to do with Inpa I might try by myself. Is the car driveable with a replaced, but not coded SAS?

[andrewwynn]

When I had a misbehaving wss I would have abs kick on when I was about to stop on dry pavement. It would do it 4-6x before it would disable DSC.

Once disabled the car drove find on Fri roads. Hazardous as hell on snow.

Similar for SAS. If not paired it will disable DSC but won't disable the engine etc.

[grachal]

I found a repair kit for the SAS on ebay. (https://www.ebay.de/itm/115304432461)
Highly recommend it.
The brushes were worn down, which you can fix with this kit. It is 90€, about as much as the cheapest chinese replacement SAS with unknown lifespan/quality. And there is no need to code the VIN as the sensors electronics stay the same.
Put everything together, zeroed the SAS with Inpa and no more DSC light


But I still have the wheel hop in the rear right corner. Yesterday I checked the wheel bearing and axle shaft by wiggling and everything seems fine. What could cause this problem? Is my diff blown?

[andrewwynn]

Wheel hop while steering happens if the diff is locked. Used to happen on my Camaro with poxitrac if I did a sharp turn when there was sand on the road.

Explore the thought of dif sticking by lifting the rear end and turning the wheels by hand it should not be difficult either side either direction. (the opposite wheel will turn the opposite direction)

Also try in neutral to confirm the drive shaft operates smoothly.

With all wheels on the ground I can't imagine how it would affect it.

Making me think back to the beginning: suspect of rust in the sensor cavity or a sensor out of tolerance either not seated all the way (what caused my similar situation) or just a factory defect.

[grachal]

Wanted to let you know, that I found the cause for the alleged wheel hop. Took a closer look down the driveline because i started to suspect the guibo and it turned out to be the driveshaft center bearing, completely shot has like 1 cm of play all around, the rubber bushing is literally gone.


No idea why it felt so much like a hopping right rear wheel, when it is the middle of the car, maybe because you sit to its left.


Ordering the part right now and looking forward to a smooth drive again.