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Discussion Starter #1
Guys, I appreciate there are a few threads on here with reference to ABS DSC lights etc but I was wondering if anyone had experienced the same as me, or had an explanation for such.

Yesterday I completed my first ever track day in the M5 and I loved it. However, on 2 occasions when I came back in, I had the trifecta lights on.

After letting the car cool for a short while, restarting the car the lights were out and normal service resumed.

I was running completely standard brakes and fluid, and I had a small issue with my front LHS brake in that I think a pad stuck slightly causing me to excessively wear the outside pad completely out, blistering the paint on the caliper it was so hot! I sourced another set of pads and changed the offending side at the track so I could get back out there for some fun!

I only mention the above for background as I was initially thinking is it possible to work the brakes and heat them so much that it could mess with the ABS system so it triggers a fault?

Is it something other track users have experienced if they were using stock brakes

Is it a "normal" feature of ABS DSC as some sort of warning that your brakes are compromised? (because fluid is too hot)

I'm really just thinking out loud, and as I only got back late last night, i'm in work on 12hr days today and so haven't had time to pull any stored codes.

And yes, I realise that using the car on track with (sub)standard brakes for that application will bring about boiled fluid etc, I'm not so bothered as I am imminently bolting up a stoptech kit and new fluid, I just didn't have them ready in time for this day so no "I told you so" posts pleasehiha
 

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Glad you got out in the M5 on a track. Was the best thing I've done with my clothes on since I was a teen LOL.

I've had the opposite on one of my M's. The lights all come on in the winter when it's freezing out?! Now it's summer it's all good. Haven't researched it much yet as it's a project, non driver car for the time being.

I think you may get an ABS/Traction control light if the pad sensor trips, thinking the pad is work down? The system doesn't want to waste pad meat controling the car when the last little pad meat needs to be saved for braking? Just a theory based on my experience with my E60 550i and it was tripping the ABS/DTC lights sometimes? The I-drive advises you to drive cautiously due to DTC inactive.
 
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I think you may get an ABS/Traction control light if the pad sensor trips, thinking the pad is work down?
When the pad sensor trips you get a "Check brake linings" and a Brake light, not the trifecta.

All that heat could be causing the ABS unit or the wheel speed sensor on the front left wheel to malfunction. The trifecta hasn't come back since?
 

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Discussion Starter #4
No mate, not returned since, although I appreciate its only been a day!

It just seemed too coincidental that on both occasions when it lit up, it was after a heavy session brakes wise. Shutting off and restarting did not extinguish the lights, but after cooling off for say 15 minutes, the lights disappeared straight away as per normal.

I was just wondering if anyone else who had tracked their car particularly with std brakes experienced the same thing, given standard brakes on short tracks heat up pretty quickly to levels where you need to back off
 

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I was just wondering if anyone else who had tracked their car particularly with std brakes experienced the same thing, given standard brakes on short tracks heat up pretty quickly to levels where you need to back off
My cars have std brakes, been tracked, and don't do this.

I don't know every symptom that can cause the trifecta. Currently I have a bad wheel speed sensor and I get the trifecta as soon as my wheel moves. When my ABS unit was bad I got the trifecta when I reached 25-30mph.

Yours being related to heat makes me think the wheel speed sensor/abs unit doesn't like the abuse, but it's just a guess. I think there is a wheel speed sensor test.
 

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No mate, not returned since, although I appreciate its only been a day!

It just seemed too coincidental that on both occasions when it lit up, it was after a heavy session brakes wise. Shutting off and restarting did not extinguish the lights, but after cooling off for say 15 minutes, the lights disappeared straight away as per normal.

I was just wondering if anyone else who had tracked their car particularly with std brakes experienced the same thing, given standard brakes on short tracks heat up pretty quickly to levels where you need to back off
The ABS module over time wears out due to .............heat!!! It typically starts displaying the lights you mentioned.

There are companies that do a rebuild and there is even a DIY rebuild here on the board somewhere. I recently sent mine out and now, no more lights.

So I suspect it is simply the heat getting to the ABS module. Next time, throw a bag of ice over it for a couple of minutes and see if that helps.

Regards,
Jerry

P.S. Here you go: http://www.m5board.com/vbulletin/e3...-dsc-abs-module-re-solder-assy-terminals.html
 
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I've had the trifecta immediately following a dyno session after pulling the ABS/DSC fuses. So I'd say one of your ABS sensors may be on its way out.
 
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I've had the trifecta immediately following a dyno session after pulling the ABS/DSC fuses. So I'd say one of your ABS sensors may be on its way out.
That's typical. Pulling fuses (17, 30) trips abs and dsc light.

Reinstall fuses, and after a few feet, lights should go out.

Regards,
Jerry
 
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Discussion Starter #9
Thanks guys.

As said I haven't pulled codes yet it was merely a think out loud moment whilst in work. I guess the next step would be to hook up INPA and see whats stored and how many occasions etc, then make a more educated diagnosis.

I'll report back.............................
 

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Jamie, the wheel speed sensors are Hall-effect with integral electronics so they are susceptible to very high temps. 200 deg C is considered high temp for them. To blister paint, you probably had it that high. It seems to have recovered so any testing you do probably won't show anything unless you play a propane torch on the wheel bearing!

And talking of propane torches, the grease in the two wheel bearings may be a bit cooked now.
 

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Discussion Starter #11
Ha! Well, one bearing at least. I only really had one side that hot because of the dragging pad, but yeah, probably another job for the list!

Cheers for the info.

Again i'm on shift today but change for nights tomorrow so will likely have a little time to read any codes and report up just for information sake
 

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Did you have anything else wrong? IE speedo, suppose you never tried the cruise? I had intermittent problem with the tri. Looked for a long time pulled each sensor cleaned them and the hole they go in and plugs also. Coated the outside and the hole they go in with dielectric grease to keep the dirt out. Dab on the plug for good luck.
Long and the short never figured out what was wrong but it has never come back. I also had a sticky caliper at the time, after you say what you have I might think that with all the dirt around the sensor, no room for heat expansion??
 

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Both of my rear wheel speed sensor failures were due to the wires connected to the sensor basically disintegrating due to old age. This caused a intermittent fault (trifecta of lights) that came on and off over the course of a couple days as the wires shorted due to the missing sheathing. Pulling the codes from the ABS module told the story, there is a specific code for a short vs. a plausible failure. A quick visual of the wires leading to the sensors should tell the story if you can't pull the codes.
 

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Discussion Starter #15
Just to update this thread i hooked up INPA today and the stored code was Wheel Speed Sensor Front Left Plausibilty, which kind of tallies up with the scorching hot corner of the car.
 
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