ABS Trifecta - troubleshooting questions
 

Hello all - I have been troubleshooting the ABS trifecta issue on my 2001 BMW X5 5-speed, and it's about to drive me crazy. Any thoughts would be much appreciated. Below is a summary of what I've currently tried / where I'm at.

Symptoms: DSC light, ABS light on (yellow), brake light on (red) - henceforth known as the "Trifecta"

Circumstances: Weirdly enough - when the car is started there is no Trifecta and I'm able to toggle the DSC switch turning on and off the light in the gauge cluster. However - once I put the car in any forward gear and begin to move, the Trifecta come on immediately. This is consistent and has been like this for months. Very rarely (say once in ~50 starts) when I turn the car on without putting it into a forward gear the Trifecta will appear - only exception is the "brake" light appears yellow in the cluster. At which point it immediately changes to red upon selecting a forward gear.

Troubleshooting methodologies tried and parts replaced:

1) using INPA I initially could not communicate with the DSC module - which I believed signified that it had failed (speedometer and cruise control stopped working at the same time). I sent it off to be rebuilt by Matt Mallory at cheap-abs.com. Upon reinstallation the Trifecta appears as aforementioned above (but cruise / speedometer now function). The failure code that populated in INPA post ABS unit rebuild was an inlet valve error (DSC error code 54 for valve inlet front left).

2) I've lived with this problem for a few months and now have finally had time to tackle it again. I checked again in INPA to see if any new codes in the DSC module had popped up and a few had. Both plausibility codes related to the front right wheel speed sensor and rear left wheel speed sensor. Through INPA, I viewed in real time the wheel speed sensors. All where operating at a consistent speed with no obvious issues.

3) since speed sensors are cheap compared to a new ABS module, I purchased two new speed sensors from ECS Tuning (Febi brand) along with new pigtail connectors where the sensors hook into the car's wiring harness since those are usually brittle with age. Today I replaced the driver rear speed sensor just to rule out the plausibly error and replaced the pigtail. Went for a drive after and the issue still exists, but the plausibility errors hadn't returned to any speed sensor after I had cleared the DSC error codes the first time. The inlet valve error remained.

4) at this point I'm about 99.9% sure the ABS module is faulty and was too far gone to be repaired properly. Since I already have the front right wheel speed sensor, I'm going to go ahead and replace it for the avoidance of any doubt.

Question to the Forum at large:

What are your thoughts? Do you agree it is likely a bad ABS module? Is there a chance it could be the ABS pump that's failed? Through my research I've not found any forum postings where the ABS pump / valve block has failed. Could it be anything else I'm not considering?

Finally the second part to the question is IF it's the ABS module, any recommendations where to source one? I've had trouble locating any new stock (e.g. FCP Euro shows it out of stock, not to mention it's major $$$). Thoughts on trying to find a rebuilt unit? I understand either a new or rebuilt unit will require some coding which isn't an issue for me to handle.

Final parting thought:

If this X5 wasn't such an oddball (5 speed manual with cold weather package / heated steering wheel / rear climate package) I'd consider just leaving things as-is, but I find myself driving it too often and hate staring at the Trifecta. Any thoughts are very much appreciated - thank you in advance!

Talk to the guys at cheap abs. The error you describe is indicative of internal fault exactly the type they repair.

The red brake is the key. Yellow usually means external sensor fault red indicates internal module fault or transfer case fault but I'm not aware of those happening on pre x-drive.

@andrewwynn - thank you for the response. I did have quite a bit of back and forth with them. Ultimately they did refund my repair fee less shipping, but were in the mindset that they had fixed the module, but did acknowledge that in certain circumstances a repaired module could still have an inlet error if it was too damaged. They did fix the communication error with the module though so it definitely was damaged. They mentioned it could be the abs pump causing the error, but that seemed unlikely to me that the abs pump and module would have failed at the exact same time.

Thank you for the clarity on the difference between the yellow and red brake light.

The other reasons for red trifecta: hand brake or low fluid so check those are working properly. I think you mentioned scanner capability that should be able to read the switches.

Coincidentally I have a module with I think the same error headed my way that I'm going to put in my car to rule out an external defect. (looking to have the same error show up when swapping out my working module). Been trying to squash a trifecta that's existed since purchase from a buddy in Boston.

Any other errors like dashboard lights persistent?

Friends don't sell BMW with problems to a friend.

:rofl:

ABS Trifecta - troubleshooting questions
 

But friends both with BMW will help the other figure out problems. You misread that. Friend that lives in Boston bought his own X5. When he bought it already had trifecta. The part is coming from Boston not the trifecta car. That is staying in Boston.

Are these modules in a spot where they are susceptible to water? Is that why some BMWs have this issue?

2003 BMW X5 E53 M54 engine,253512KM

No: heat. Heat kills and it's too close to the engine. Also too close to the shock of the suspension.

I have had my abs temporarily knocked out from a big puddle but that was a wss connector problem.

Heat will do it for sure,and why put it in areas like that,must be a better place to put these modules.

Sent from my SM-G950W using Xoutpost.com mobile app

Often the ABS module faults are caused by the fine wires that connect the pins on the external connector to the internal circuit board failing. The same fault occurs on the M57TU glow plug controller. In the case of the glow plug controller, it's easy/cheap to replace the entire module (no coding etc.) - but it's not so easy with the ABS module.

Damage to the fine connecting wires is caused by a combination of heating/cooling cycles and vibration.

https://www.bimmerfest.com/attachmen...08-jpg.227831/

Aka "bond wires" and they are welded not soldered so very difficult to DIY repair.

Those wires look very 80s. I appreciate every time I see old school electronics how you can see a human soldered all those components and everything is so big.

Wonder why they chose to go that route, looks like old school tech mixed with

ABS Trifecta - troubleshooting questions
 

Machine robot welding for speed equals faster equals cheaper. They just under estimated the required bond wire size or didn't engineer in enough stress relief.

In Navy Electronics school they taught us to put a 270° curl into through hole components if the holes are close to the end of the resistor etc. So smart and greatly improves reliability.

https://uploads.tapatalk-cdn.com/202...0bca1d953d.pnghttps://uploads.tapatalk-cdn.com/202...8aa2fdb221.png

Those are from a nasa website showing some stress relief for soldering designs (I couldn't find the 270°; that's for when the through hole is too close to the ends you would have to make too sharp of bend.


If Bosch simply put a tiny zigzag into the bond wires we wouldn't be having this conversation.

They prob programmed the bond wires to be tight to not vibrate but everything ever is a spring they just changed the frequency while adding stress to the ends.

Very interesting.

I don't know much about electronic components or design and my soldering skills are fairly basic but I've always enjoyed messing around or trying to fix small electronics.

On this video you can see how the machine does wire bonding with ultrasonic welding.

They can be repaired by soldering with copper wire but you need special solder like Alusol and more heat than typical solder. Not recommended if you are not familiar with this.

https://www.youtube.com/watch?v=Nxum...l=ACtronicsLTD

Perfect video to showcase the issue

You should check the pressure switch pressure when static ignition on engine off. Should read 0 bar if it doesn’t the light will be on. Then press brake pedal and should raise accordingly. If not as above then change the pressure switch.


Sent from my iPad using Xoutpost.com

All thank you for your comments and Merry Christmas! Wanted to follow up on some additional troubleshooting from yesterday.

1) through INPA, I verified the handbrake functions correctly, this isn't the issue.

2) completed the replacement of the front right (passenger) wheel speed sensor which occasionally threw a plausibility error, but as pointed out earlier in the thread the "brake" light in the gauge cluster was illuminated as "red" and not "yellow". Red typically means ABS module issues and yellow typically means wheel speed sensor issues. As an aside, it was a giant pain replacing the abs sensor. The original sensor was stuck in the hub and so brittle it disintegrated at both the connection to the car's wiring harness and broke off in the hub. Luckily I had a new pigtail connector on hand to replace where the ABS sensor hooks into the car's harness. Then after very carefully drilling out the old ABS sensor, cleaning the hub / magnetic ring, reinstalling the new Febi ABS sensor, I was able to rule out any wheel speed sensor issue. To aid in the troubleshooting I turned the X5 on without plugging in the abs sensor and immediately the Trifecta (with yellow brake light) appeared in the cluster. Makes sense since that's how it should be. I then plugged in the connector, put the wheel back on, lowered the car, and went for a test drive (After clearing the DSC codes). Upon starting the car before setting off, no Trifecta lights, but after putting the car into gear, the Trifecta (with red brake light) appeared. :cussing:

3) checking the DSC codes once again return the inlet valve error, but no wheel speed errors (and I verified all wheel speed sensors report the same values when moving)

I will check the brake pressure sensor, but I'm pretty sure all signs point to the module at this point - especially thanks to the stubborn inlet valve error. Any other suggestions before I give in and order either a rebuilt or new abs module?

Thanks!

My buddy from Boston has the exact same error I believe. We've been trying to squash the bug for quite a long time.

He's sending me his module to put in my car and see if the code will then show on my car

Because this is an ABS post I will relate how my problem was resolved. After diagnostics with a number of faults (can’t remember the codes) I sent my ABS module of to ECU TESTING as it had previously been repaired by them and was under lifetime limited warranty. Got it back saying they couldn’t find a fault but had "tidied it up ". Still had the fault. They asked for the complete pump and module. This came back with no faults. Refitted and still had same fault. They asked for the module again and this time informed me the module was toast and beyond repair?? All of this was free of charge, they sent their own courier. They offered me my original £240 repair cost back (from 2 years previously) or a brand new module which they would upgrade to their standard for an additional £150 but I would have to wait 2 weeks for them to get one. I agreed. Got new module. Same fault. Finally looked at brake pressure and found that static I was getting a reading of 192 bar pressure. Googled the p/n and found the switch was fitted to a number of cars ie Volvo/VW and some others. Went to recycler and got the part from a VW Passat £2 and fitted. Static pressure 0. All warning lights gone. No more problems. I probably didn’t need the new module, but what price some good knowledge. I considered ECU Tuning were more than fair in how they dealt with me.


Sent from my iPad using Xoutpost.com

Just read this thread, lots of good info. I’m the friend who sent Andrew a module to swap. Been dealing with trifecta since purchasing my X5, have tried numerous things like the OP has. OP hope you get your issue resolved soon, and let us know what solution was. Like you said, trifecta always on drives you crazy after a while lol

@Boston01X5 - yes, will definitely post a resolution once (assuming if) I can get this resolved. I read through another thread where someone had a similar issue as mine (no Trifecta on until the car is put into gear and moves a few feet), the explanation in that thread was that apparently the X5 does an abs system check in roughly the first 50 feet of travel. This explains why my Trifecta only appears after beginning to move the X5 rather than immediately upon start up. That must mean the system thinks everything is fine until it actually tries to engage the ABS system / module at which point it detects a problem (e.g. inlet valve error). Is your issue also a valve error?

@Henrym3 - do you happen to remember what error you had? Was it by chance a valve error?

I think that the error is valve relay error. I think it's a bond wire problem but at the age of these things could easily be solid state error.

Yes it was valve errors, should have kept notes but got so pissed off with sending things back and forward. To be honest I was getting desperate as all the experts were telling me there was no faults. In the end it was so simple you always wonder why the hell you didn’t check that first. To be fair I hadn’t read anywhere about pressure testing, just seen it listed on my Foxwell and then thought it didn’t seem right to be getting massive pressure without the engine running. Took a wild assed guess and changed the pressure switch.


Sent from my iPad using Xoutpost.com

When I saw this post a few minutes ago I went outside and hooked up Foxwell and brake pressure reads just fine. 0-40 Bar. I was hoping this was the cause of my trifecta but wasn’t that lucky. Thanks for the tip though. Definitely worth taking a minute and ruling that out since it’s so easy.

So you are talking about the pressure sensor at the back of hydraulic block?

https://www.pss-autosoft.net/diagram...s/G_154049.png

Some info regarding the pressure sensor.

https://www.pss-autosoft.net/diagram...-3450-005C.htm

Valve errors can be caused by failed valve itself on the hydraulic block (very rare), coil driving the valve (rare) or components on the control module driving the coil (most common). Unfortunately in many cases the base problem has been failing internal ground wiring on the module (same type welded wiring as for wheel speed sensors) which when abruptly cutting power eventually causes component failure which many refurbishing companies deem beyond repair.

Yep, that’s the one on the back.


Sent from my iPad using Xoutpost.com

That’s an interesting read. Didn’t know any of that. So is ignorance bliss or I just got lucky? I find it amazing that there is no tolerance in the test pressure. Below 80bar it’s the switch above it’s the pump.
Just as an add, there was very little loss of fluid when I changed the switch although I had the replacement one ready to put in straight away. I also bled the brakes again


Sent from my iPad using Xoutpost.com

Very interesting point: a rapidly disconnect will send a voltage spike. The exact principle that generates the ignition spark. I would not be surprised if a broken bond wire closes and opens like the points of an old timey ignition coil and generates a high voltage pulse that kills something in the circuit.

If there is anyone who can take apart a module and take great pics, explain what failed its Andrew. Waiting on USPS... was supposed to be there the 24th delayed because holiday.

I grabbed a module from junkyard with same numbers and it gave me same exact codes (no programming necessary) and everything else works fine so can drive with same symptoms.

So either two modules both failed the same way or we will figure something out once he plugs it into either of his vehicles that have working DSC and no trifecta (again all modules have same numbers so no programming needed).

(Ball in your court Andrew)

;P