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My Mechanic cant solve it and neither could I

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TLDR: Neither I nor my shop can find what the issue with my DSC is

My 2006 BMW X3 146k is limping along. I am trying to get rid of the annoying "holy trinity" of lights. My work started with a clunking front end when driving and the 4x4 DSC and ABS lights coming on with the clunk. I got rid of the clunk noise when I replaced all 4 calipers, and both front CV axles. The front passenger CV axle had broken at the U joint. While doing this work I managed to break one of my wheel speed sensors. I replaced it with a wheel speed sensor from O'Reillys. I believe it was the front left.

I have now been chasing the codes that still come on the dash whenever I gas medium or brake medium. The car gives a slight hesitation when it gives this fault condition and the lights on the dash come on with a beep. Ive verified that the wheel speed sensors are reading correctly by plotting a graph of the sensors readings.
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The codes that my scan tool currently bring up are 5DEC transfer case malfunction, 5E5C Wheel speed sensor direction-of-rotation detection, and 5EB1 steering angle sensor supply.

I have tried taking the car to my local shop, a reputable mechanic I trust a lot. When I first brought it to them they said that the SAS was far out of alignment, that they reset that and the problem should be fixed. The light came on the next day. They said they were unsure of the issue and they proceeded to do the free transfer actuator repair seen on here. They gave me the car back and the light came back on the next day. I brought the car back, they held the car for a few days, I didn't mind as they hadn't charged me for the work on the actuator, and then after about 5 days they said to come get the car. They said that they're pretty certain its the transfer case itself, and advised that I continue to drive the car until the transfer case fully breaks, rather than pay 2k right now for a new one.

I would really like to get a full answer of the problem, Im more than willing to try any and all diagnostic suggestions but I've really ran out at this point. Any help would really be appreciated.
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I would suggest you take it a to non-dealer BMW Specialist....one familiar with the all-wheel drive cars.

It does look like your speed sensors work

Have you searched on-line? I searched on just one of your codes and found this:
I have tried looking online but not to much avail. A lot of the people don’t seem to have a diagnostic path of things to check in order to verify proper operation. They just suggest load up the parts shotgun. I haven’t found a bmw specialist that seems reasonable. Im in Massachusetts and took the car previously to import autowerks for a vacuum leak and they did a smoke test and charged 800$ but said they couldn’t find the issue and recommended additional work. I made a smoke tester for 30$ out of a pickle jar and a bike pump and found the issue in 30 minutes was just the vacuum caps on the intake manifold. It seems hard in the world of bmw to find reasonable repair people.
Thats accurate. I've found that most times the BMW "specialists" does no more then what we do. Its that we may not have time or resources or the tools.
Your experience is a prime example. I've found that the problem is mostly exacerbated into something major when in reality a modest fix is the remedy.
Long live the DIYer!
Cheers!
A lot of the people don’t seem to have a diagnostic path of things to check in order to verify proper operation. They just suggest load up the parts shotgun. I haven’t found a bmw specialist that seems reasonable. It seems hard in the world of bmw to find reasonable repair people.
This issue - is not an easy diagnosis, though it may be a pretty simple fix.

You will need second level BMW-specific diagnostic tools, (INPA, ISTA, etc.) to diagnose, reset and calibrate sensors, etc.

I suggest you drive over and see Jake at BMW specialist Wile Motorsports in Walpole, MA and have a (free) conversation with him about it. I am confident he can fix it and not charge you an arm and a leg.

If you want to try and tackle this yourself:
  • get INPA or ISTA-D loaded on a laptop with correct cables.
  • Double check that you have all the codes
  • spend a weekend or more reading every online post you can - not just E83, but E46 and frankly any BMW that has same codes.
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Setting up a windows Pc with ISTA/D. I will need to see if I can setup the correct cables. I have a obdII - vga cable for my scan tool so I’m gonna try using that on the pc and see if it works with ista. Otherwise I will take a look at wile motor sports in Walpole. I could really use a better bmw specific mechanic than what I’ve found around me.
FWIW, check the starboard rear axle near the tone ring for scale or flaking paint. I traced a triad of lights and SAS code that ONLY appeared on a very specific instance (slight uphill on a 90* right turn at 5-10 mph, with front tires on ice) to scaling paint on that axle. During suspension unloading and front tires slippage, the DME got confused. I pulled that WSS, stuck a pipe cleaner in the hole and rotate the axle to clean it, then acid treated the axle. The starboard rear reluctor is usually the first to fail.

I’m not saying that’s your issue, but is an example of why codes are not absolute.


Buy socks on Amazon, not car parts.
So all 4 of my steering knuckle assemblies are rather rusty. Do we think I should take out each wheel speed sensor and try and clean them? What acid do you use to clean it? Muriatic?
I use Ospho for all my metal-preps, but any acid will do, even vinegar. Soak, rinse, done.

On your graph, the wheel speeds diverage at the end; what happened there? Make a turn? You may want to look down the WSS bores with a light while spinning the axles to look at the entire reluctor, and take a depth measurement with a caliper in at least the 4 quadrants to be sure the reluctor isn't being lifted by rust. A little ring lift coupled with a little bearing play could bring an error during loading/unloading of the rear suspension; just hypothesizing there.
So all 4 of my steering knuckle assemblies are rather rusty. Do we think I should take out each wheel speed sensor and try and clean them? What acid do you use to clean it? Muriatic?
I’ll check out inside the hole where the speed sensors go in. And the divergent spots are turns. Blue and gray is the left side and orange and yellow is the right side.
For cleaning the steering knuckles, can I do your acid wash with the knuckle still on the axle? Id rather not have to pull it off the car again if I don’t have to. I think I’d do get the car on jacks, take off wheel speed sensors and tires, wire wheel inside hole with pipe cleaner while spinning each hub, degreaser inside each hole, then water in, then acid in, and then water rinse. Does that sound good?
(y) I usually don't bother with degreaser as it won't affect magnetism unless it is antiseize; it shouldn't be greasy anyway unless your wheel bearings are failing or CV boots are cracked. If so, you'll never not have a WSS issue. Definitely use a catch basin so you don't acid wash the shop floor.

I'm also not saying that will solve your issue either, but I find it prudent to establish a baseline before diagnosing further. I despise rust and try to correct it every chance I get. Make sure to wire-brush the knuckle surface where the WSS sits to ensure it is seated fully.
Ok sounds good. I’ll go give this a try. Good suggestion on the catch basin I commonly forget that.
After putting MANY dollars into trying to fox a 2008 X3 that the brakes seemed to actuate by themselves, The mechanic found the wiring harness had been chewed up, and the main alternator cable was corroded to the point of falling apart. Replacing the electronic half of the ABS module seemed to finally do the trick. Your problem sounds a bit different, but don't overlook the wiring harness.
Could it be partly due to the classic Transfer Case Actuator failure, perhaps just the gear inside is worn out?

(2) Transfer Case Actuator Fix | BimmerFest BMW Forum

BMW Transfer Case Actuator Problem and Fix - AxleAddict
TLDR: Neither I nor my shop can find what the issue with my DSC is

My 2006 BMW X3 146k is limping along. I am trying to get rid of the annoying "holy trinity" of lights.
It could be the transfer case actuator failure but given that they rotated the gear and said they found the gear not to be worn I am doubtful that it is the culprit
Check those tone rings. I had a no code , complete shut down of power issue a year ago that finally traced back to rear starboard tone ring, Just like Duke.
‘’I partscannoned coils and fuel pump (pressure showed some wierd oscillations) before noticing noise on the WSS signal.
do you have real time data on the WSS?
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I only have the data logged through my scan tool. I’m setting up ista today so hopefully that will be able to deliver real time data? I think my scan tool records like once per second.
I had a similar, but not not exact problem. I used scan tool to monitor LIVE DATA while I drove car. I noticed automatic transmission shaft speed sensor would give an interrupted signal. I replaced it with some effort as it resides in tranny. Problem went away. My point is to be patient and use any diagnostic reading you can get.
Any update? I'd still recommend a free convo with Jake at Wile Motorsports in Walpole
I only have the data logged through my scan tool. I’m setting up ista today so hopefully that will be able to deliver real time data? I think my scan tool records like once per second.
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