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The DSC Trio! 3 Lights on dash. The basics done but still no luck.

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Yet another DSC light trio question, hopefully I have got to a point where the usual stuff is done and I have given enough information to make it clear. Help would be much appreciated, thank you in advance. I will be sure to provide the solution once fixed to help others which many people don't do ahhhhh!

Came on one morning out of the blue. DSC, ABS and brake light, orange on the cluster. Goes off some times for long periods but always return.

Reading many threads, I then carried out the following:

- Used a C110 Scanner to find fault codes, the general ones came up indicating front right wheel speed sensor.

- Removed both front sensors, cleaned sensors, rings and connectors. Cleared codes and drove. Fault still there.

- Replaced front right wheel speed sensor. Cleared codes, fault returned.

- Replaced ABS Unit and module. Coded unit to car using INPA software, reset steering angle, cleared codes, fault returned but a different set of codes appeared. 5E5D (Level sensor, break fluid) and 5DA2 (Wheel-speed sensor, pulse gear, front right) have been present all along but 5DF4 (System Voltage < 9 volts) is new.

-Checked battery. Producing 12.4v so its fine. 

Below are images of the current code readings from the C110 scanner. These are the same as when I use the INPA software on my laptop.

What I have noticed is that the ASC data request function has been stalled on a set of random figures (as shown) since the fault occurred. The other readings on the scanner such as ABS data request work fine and change as you drive. The ASC one does not.

Current fault codes are:

5E5D (Level sensor, break fluid)

5DA2 (Wheel-speed sensor, pulse gear, front right)

5DF4 (System Voltage < 9 volts) is new.

My thinking has it down to wiring or ABS ring. The 5DA2 code is different from the actual wheel speed sensor code which disappeared when I put the new sensor in.

If it is the ABS ring, I am correct in saying this is part of the front hub and cannot be replace on its own. I have thoroughly cleared the ring with degreaser and a toothbrush and only found very minor wear on it. I have recently replaced all my brakes and I have read that the new brake dust muck around with the ring.

Does anyone have any suggestions to what it could be or previous experience in solving an issue similar to this? I have checked all the fuses as well which are fine.

Cheers!

 

 

 

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Apologies I don't have a solution for you but about to get stuck into fixing the common ABS/DSC not working issue on my motor, but interested to know the following, as it might save me some head scratching further down the line.

Do the most recent set of error codes still cause the DSC, ABS and Handbrake cluster lights to glow orange? I read somewhere that the presence of the orange handbrake cluster light in combination with DSC & ABS usually indicates an issue with a rear wheel speed sensor - however, your diagnostic kit has pointed to speed sensors at the front. With regard to the low voltage, could it simply be a poor electrical contact where the new ABS unit takes it's power feed? Are you able to cycle the ABS/DSC motor ok using your diagnostic software?

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Well it was the pulse (ABS) ring on the rear of the bearing as indicated by the fault 5DA2. I should of changed that first, especially before the ABS unit!

Changing the wheel bearing (Front pulse rings are part of the bearing unit. Rears are separate replaceable parts) stopped the fault code appearing but has not made the data stream for the ASC work which is odd but the other ASC data stream works so not too worried. 

The two other faults (5E5D & 5DF4) disappear over time before I fitted the new bearing. Which is why I chose to replace the pulse ring.

On 24/04/2017 at 22:56, B.Merr said:

Apologies I don't have a solution for you but about to get stuck into fixing the common ABS/DSC not working issue on my motor, but interested to know the following, as it might save me some head scratching further down the line.

Do the most recent set of error codes still cause the DSC, ABS and Handbrake cluster lights to glow orange? I read somewhere that the presence of the orange handbrake cluster light in combination with DSC & ABS usually indicates an issue with a rear wheel speed sensor - however, your diagnostic kit has pointed to speed sensors at the front. With regard to the low voltage, could it simply be a poor electrical contact where the new ABS unit takes it's power feed? Are you able to cycle the ABS/DSC motor ok using your diagnostic software?

Sorry for the later reply B.Merr. I would go with what the fault codes are indicating. From forum reading it seems that if a rear sensor has gone the speedometer will stop working, so that is your best clue. Lots of info on that available with a quick google search.

Start by removing and cleaning the wheel speed (ABS) sensor and pulse ring. Have a look/feel of the ring to see if there is any damage. Mine had slight rubbing which could of caused the issue. If that does not solve the problem then change either the sensor or pulse ring. Either one should fix the issue or prove that it is the other at fault. Best of luck!

I got the abs to cycle fine when I changed the abs pump but only after fining that a fuse for the ABS was missing from the fusebox in the glove compartment,

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I've just replaced the entire front hub with a know working used one, and then replaced the abs ring & sensor with new ones because of this - it's cleared my ABS light but the other 2 are still there so i'm suffering the same as you! Oh and I get zero codes, nothing, not a sausage!

Sorry I don't have anything more helpful to add than that, just showing solidarity for this royal pain in the arse fault.

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Thanks to both of you for taking the time to document your findings. It's really helpful to owners researching how to resolve braking system issues and we all sympathise!

Postman delivered a copy of INPA with OBD lead this morning, after a couple of IT headaches the ABS/DSC error codes were read, highlighting 5D93 front left wheel speed sensor...so looks I might get off lightly this time. As previously advised I'll unbolt it, clean it up and retry and if necessary replace with a new sensor then hope that is the end of it.

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Regarding the rear wheel sensor going and speedo failure, I was told that thats the fault you would get 'only' with the rear 'right'. If the rear left sensor goes it takes out cruise control and the speedo still works. I had to deal with the same lights scenario as the op, but in my case the speedo was (also) working fine, and the problem with mine was definitely rear left sensor.  As to any other issues with fronts/bearings/reluctor rings, i leave that to others.

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Having got the hang of INPA, did a test drive with the laptop hooked up and software running, showing analogue view of all four wheel speed sensors. For the first 90 seconds of the drive all four sensors were showing the same speed, then I heard the ABS pump buzzing for about 10 seconds, looked across at the screen and front left wheel sensor speed shows zero, other three as expected. Got home and read errors from the DSC module: 5E24 pressure sensor 1/2 not plausible, 5E21 pressure sensor 2 electrical failure, 5D94 wheel speed sensor front left long term supervision. Will trawl the forums for info tonight and investigate further tomorrow...

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I was having pressure sensor errors and solved them by cleaning up the connectors with lots of brake cleaner, and plugging/unplugging the connectors a few times, spraying again, plugging/unplugging again to clean them up, then shaking dry and reconnecting. A long shot perhaps but it's free.

You should be able to see the pressure sensor live data on your diagnostic, when I was cleaning mine up the data began to gradually reduce further to zero, so I needed to spray ang unplug/connect a few times, to mechanically clean up the contacts, and once the plugs had completely dried out it was perfect - about 0 with no brakes applied. The first time I cleaned them it helped for about a week but got bad again, but after a really thorough cleaning all has been well for over a year now.

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Thanks for the tip, I'll clean up the brake pressure sensor contacts and re-test this weekend. Most recent error logged is 'electrical failure' on sensor 2, which suggests a poor connection.

When attempting to remove the front left wheel speed sensor for inspection the head sheared off the allen bolt fixing. Arrgghh!  Removed the calliper carrier (with calliper attached) by removing the two 16mm bolts. Next removed the disc. At this point the tip of the wheel speed sensor is visible and it prized out with gentle persuasion. The sensor was surprisingly clean. Used electrical contact spray to clean it, reseated the sensor by friction fit. Unplugged the other end of the sensor, located in the wheel arch plastic box, and cleaned that too. Cleared the codes and went for a spin....still an error on the front left sensor, so it's time for a replacement part.

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Oh well at least your on track to sorting out the ABS sensor even if removing it didn't go totally smoothly.

I hope cleaning the pressure sensor contacts helps, if you have live data on a diagnostic this should help you to assess whether the cleaning is making any difference. In my case the first time I cleaned, the sensor reading improved a bit, but I needed to clean and reseat the connector a couple more times before the readings went to normal values. The plug for one of the sensors is difficult to access, from memory I used a screwdriver or pliers to press on the locking mechanism on the connector to allow it to unlock.

For reference, a 'normal' reading without the brake pedal pressed is close to 0 bar, mine both read a slightly negative reading at the moment, say -0.2 bar. If the readings are creeping up,  say showing 3 bar upwards, then this could be dirty contacts. I think the trigger point for the warning lights is about 10 bar without the brake pressed, so if one reading is close to that number, at certain times it might jump over the threshold and trigger the fault code and warning lights.

Would be interesting to hear from you what the readings are showing, to see if they're similar to those above which I had with the dirty contacts.

When you press the pedal, both sensor readings will go up, on mine they are pretty much identical no matter how hard the pedal is pushed.

Good luck with it!

Edited by Tim-Ci

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Snapshots taken from INPA's 'DSC-Sens.' option, under chassis/dsc mk60 -

Without brake pedal engaged: Circuit1 = 0.14, Circuit2 = 73.88

With brake pedal firmly engaged: Circuit1 = 59.01, Circuit2 = 119.36

5E21 pressure sensor 2 electrical failure still generated after error clearance and re-read.

I'll try cleaning the sensor contacts tomorrow, then watch the live dsc diagnostics again.

Still waiting for the wheel speed sensor to be delivered...

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Your sensor 2 readings are well off, it should read the same as sensor 1 with and without the pedal pressed (sensor 1 is is reading pretty much perfect). If not the sensor/connection then you have something mechanical causing much more pressure in the 2nd circuit, but that's unlikely. I hope sensor 2 is the easier one to get to....

If you see a drop in the sensor 2 reading  after cleaning you're on the right track, it took a couple of times cleaning and reseating my connectors before the readings dropped down to almost zero. Make sure you dry the connector and sensor contacts after spraying them before plugging it back in, compressed air would be best but blowing on it will work.

Good luck! Let us know how you get on.

Edited by Tim-Ci

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...unplugged both brake pressure sensors and cleaned with electrical contact spray. Didn't make any significant difference to the live brake pressure readings as viewed in inpa. Puzzling how sensor 2 consistently reads approx 60 bar higher than sensor 1, irrespective of whether the brake pedal is applied or not. Anyway, on your advice repeated cleaning, reseating and testing three times, so assume the sensor monitoring circuit 2 is malfunctioning and have ordered a replacement part. Meanwhile, the wheel speed sensor arrived in the post today - now waiting for a break in the rain to get outside and swap it over...

Having trawled the forums for info on braking system errors, seems to be a common age related issue affecting several BMW models from the era. Other owners have, like yourself, had a result by simply cleaning the rogue sensor, only for the dash warning lights to return a few months later.

I also bled the brakes with the inpa dsc bleed function, in the hope that the unexpected pressure readings were simply being skewed by trapped air bubbles in the braking system - again didn't make any difference.

Next task is to research how to swap out a sensor from the master cylinder without making an almighty mess with brake fluid!

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Very good luck with it, that does sound like a messy job. Shame cleaning the contacts made no difference.

Luckily cleaning the connectors has worked for over a year now on mine, so I consider the fix permanent, I must be lucky this time round (not so lucky with my oil level sensor which has recently started playing up out of the blue.).

Yes I agree once you swap the sensor the for a new one the reading should be normal. It's very useful you have a decent diagnostic tool, it's so good knowing what is actually being reported by the sensor.

The only other one in a million chance thing I would try is to start the engine so the brake servo is working, and stand on the brake pedal as hard as you can, a few times, in case some kind of blockage or contamination has occurred in the sensor, and that flushes it out and frees it up. Probably won't make any difference though.

Good luck, do post back once you're warning light free!

Edited by Tim-Ci

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...front nearside wheel speed sensor replaced a week ago or so, with a mayle part (looked to be good quality part and perfect fit). Cleared brake system fault codes with INPA, started the engine and the ABS light is no longer illuminated. Probably 30 mins effort to swap the part, although I had been in the vicinity before (see earlier post). Received a brake pressure sensor in the post, advertised as "OE quality" but looks poorly manufactured even to my untrained eye. Had a poke around the master cylinder with a spanner but decided it looks like an @rse of a job to replace it with those brake lines fouling access....left it until I've worked up the courage to give it a shot! 

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27mm spanner arrived in the post today and the skies cleared at 6pm so Idecided to have a go at this task since all necessary tools and parts are finally to hand. Slid an old cotton hand towel down past the master cylinder, into the void below. Placed a 2ftx3ft piece of cardboard (recycled packaging) under the car, directly below the master cylinder, to catch any spilt brake fluid. Using INPA, established pressure sensor 2 is furthest from the bulkhead, carefully prized the pressure sensor electrical connector away using an old 12" chisel. Using an 11mm open ended spanner gently cracked nut holding the brake line directly above pressure sensor 2, this line is attached to a braided flexi hose and needs to be moved to one side in order to gain access to the pressure sensor. Inside the car pumped the brake pedal until firm. After half a turn with the spanner the 11mm nut was removed by hand, gently cracked the pressure sensor using the ring end of a 27mm spanner. Again this component was easily unscrewed by hand. At this point noticed a lot of brake fluid spilt. Quickly screwed in the new sensor, just a couple of quarter turns with the spanner to tighten. Reconnected the brake line and tightened the 11mm nut by hand, then again just a couple of quarter turns with the spanner to tighten. Wiped away excess brake fluid from the engine bay, extracted the old towel, which was pretty sodden with fluid, bagged it and binned it. Brake reservoir empty so refilled to the max line, it took accepted approx 200ml of fluid. Removed the cardboard from underneath the car, this was soaked with brake fluid. Obviously a brake bleed is now required, but out of curiosity I pressed the brake pedal and the travel is further, only by around an inch (expected pedal to be loose). Started the engine and brake pedal travel still only an inch more than it was before sensor replacement. Trundled the car up and down the cul de sac a couple of times and the brakes were as effective as previously. No dash warning lights displayed at this point. Plugged in INPA, cleared DSC MK60 error codes, switched to analogue DSC monitoring, brake pressures across circuit 1 and 2 almost identical. Drove around the block, re-read the error codes - no errors found. Will pressure bleed all four corners and the clutch tomorrow morning with the old eezibleed. All braking system issues appear to be resolved (touch wood), if anything unexpected occurs in the near future I'll update this thread.

Tools and parts purchased to resolve braking system issues flagged by dashboard warning lights:

Copy of INPA software (£24), wheel speed sensor (£27), DSC pressure sensor (£26), 27mm Spanner (£5)...around £80 in all.

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Nice guide to replacing the pressure sensor - sounds like a good result. I imagine it will be reassuring not to have any warning lights flashing up. It sounds like a good price for the pressure sensor, if the readings it gives are close to the other one then I consider that a good deal you got.

You might want to consider using INPA to bleed the DSC pump, which might help shift a bit more air from the system than a standard bleed would. This video goes into a bit of detail about it:

 

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Hi just changed my rear right pulse ring,I had the cluster of lights on before abs etc,when cleared the faults lights wouldn't come back on until I drove the car,now I have changed the pulse ring it goes a little further before the lights come on. Does the pulse ring need to be perfectly centred to the speed sensor?

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