DSC light comes on at 20mph

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Tufarlian
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DSC light comes on at 20mph

Post by Tufarlian »

Hi guys. Hoping for a little advice please.

The DSC light on my 2000 3.0 Z3 has recently started coming on at 20 mph.

You can drive around as long as you like below 20mph but when you go over that the DSC light (only the DSC light) comes on and stays on until you turn off the ignition.

My code reader software (ProScan) seems only to read the engine codes and shows no stored error codes.

I'm not able to get INPA to work so I'm struggling to find out where the problem is.

I have removed and cleaned both rear wheel sensors. I've not done the fronts as they are stuck in place and I don't want to break them. I've also disconnected the battery for an hour to reset the systems but the DSC light still comes on at 20mph.

Anybody seen this before?

Any advice appreciated.

Thanks

Mark
Jonco
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Re: DSC light comes on at 20mph

Post by Jonco »

Tufarlian wrote: ............I'm not able to get INPA to work so I'm struggling to find out where the problem is..............
Which INPA version have you got? I have the BMtechnics and it works ok on a `98 1.9 - never tried it on anything else yet. Whereabouts are you in Cheshire?
John Wilson
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Re: DSC light comes on at 20mph

Post by John Wilson »

I've found that the front sensors are more likely to be at fault because they are the ones that are more exposed to spray. That is why they are also more difficult to remove. I understand your reluctance to remove them. I had one shear of and it then needed drilling out and retapping. It's worth trying releasing oil over several days (not WD40). Good luck.
John
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Tufarlian
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Re: DSC light comes on at 20mph

Post by Tufarlian »

INPA 1004 4_2005, ELM327 USB and BMW adapter. Win XP laptop.

ProScan works both in the round under bonnet socket and the standard OBD socket under the steering column. ProScan and my Ford specific software also works on wife's Focus and daughter's KA. INPA loads OK but just crashes when you try and run a script. Error is "IFH-0003: Data transmission HOST/Interface failed". tried all sorts of things found on various forums but with no luck.

I'm in Middlewich and do get over to Chester occasionally. If I buy the beer can we meet up and try your BMTechnics setup?

Thanks
Mark
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Re: DSC light comes on at 20mph

Post by Jonco »

Tufarlian wrote: .........INPA loads OK but just crashes when you try and run a script. Error is "IFH-0003: Data transmission HOST/Interface failed". tried all sorts of things found on various forums but with no luck.

I'm in Middlewich and do get over to Chester occasionally. If I buy the beer can we meet up and try your BMTechnics setup?
Sorry can't help with the error code but willing to try my set-up on yours - will drop you a pm.
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Tufarlian
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Re: DSC light comes on at 20mph

Post by Tufarlian »

John Wilson wrote:I've found that the front sensors are more likely to be at fault because they are the ones that are more exposed to spray. That is why they are also more difficult to remove. I understand your reluctance to remove them. I had one shear of and it then needed drilling out and retapping. It's worth trying releasing oil over several days (not WD40). Good luck.
John
I can get the allen bolt out but the sensor itself is still stuck in there. If I knew it was duff and I had the replacement I'm sure I could get it out but I don't want to damage a possibly good sensor.

I'm not completely sure my problem is a wheel sensor anyway because I don't get any ABS light, just the DSC light, but most threads I can find still seem to have the wheel sensors as likely culprits.
Del
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Re: DSC light comes on at 20mph

Post by Del »

Done any work on the front axle or bumped a curb? Alignment issues can cause this sort of problem.
Del
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Re: DSC light comes on at 20mph

Post by Del »

Other indirect causes can be tyre wear and incorrect tyre pressures. Wheel sensor dirt/faults or chaffed wiring to the sensors are common causes though.
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Tufarlian
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Re: DSC light comes on at 20mph

Post by Tufarlian »

Del wrote:Done any work on the front axle or bumped a curb? Alignment issues can cause this sort of problem.
Not exactly. Did put 2 new tyres on the front but that was weeks before this problem showed up.

Thanks for the pointer though. One more thing to check out.
t-tony
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Re: DSC light comes on at 20mph

Post by t-tony »

In my experience DSC, ESC and all other variations on traction control use the wheel speed sensor as well as the ABS system. But it still could be the wheel sensor at fault.
"Knowledge and experience are not always the same"
Brian4
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Re: DSC light comes on at 20mph

Post by Brian4 »

The DSC system include a steering angle sensor on the column and 2 sensors under the passenger footwell carpet. After all this rain has the carpet there got wet and upset the sensors. Some of the INPA do not read the DSC system.
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Tufarlian
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Re: DSC light comes on at 20mph

Post by Tufarlian »

Brian4 wrote:The DSC system include a steering angle sensor on the column and 2 sensors under the passenger footwell carpet. After all this rain has the carpet there got wet and upset the sensors. Some of the INPA do not read the DSC system.
I have read about the yaw sensors under the passenger seat. Carpet doesn't feel wet but it's been raining so much lately that I can't honestly say the car is bone dry inside.
I've no idea how to check the steering wheel sensor. Jonco has offered to try his working INPA (thanks mate) later this week and I'm hoping it gives me something to go on.
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Tufarlian
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Re: DSC light comes on at 20mph

Post by Tufarlian »

In my messing about trying to track this down I have found that the NSF spring is broken. Looks pretty recent.

Could this cause the DSC light to come on?

And a supplementary question - any recommendations for standard springs, and I suppose shock inserts while I'm in there, or is it best just to go to BMW?

Thanks
Mark
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Tufarlian
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Re: DSC light comes on at 20mph

Post by Tufarlian »

Many thanks to Jonco for reading the codes with his INPA setup.

Code 177 DSC Pre Charge pump failure.

Scarily expensive for a new one but I checked the DSC and ABS fuses and found a popped one.
Replaced and all is well now. Result. :-)
Here's hoping it was just a one off and it doesn't pop another fuse.

Now, just that spring to get sorted......
Jonco
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Re: DSC light comes on at 20mph

Post by Jonco »

Tufarlian wrote: Scarily expensive for a new one but I checked the DSC and ABS fuses and found a popped one.
Replaced and all is well now. Result. :-)......
Great news - had been looking at wiring diagrams and was going to suggest fuse but you beat me to it.
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pingu
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Re: DSC light comes on at 20mph

Post by pingu »

Tufarlian wrote: I can get the allen bolt out but the sensor itself is still stuck in there. If I knew it was duff and I had the replacement I'm sure I could get it out but I don't want to damage a possibly good one.
Not relevant to you now, but you can test a sensor if you have an analogue voltmeter. Connect the two sensor wires to the voltmeter and spin the wheel. If the needle flutters, sensor is working. Good quality digital voltmeters can also be used, but the lag in a cheap voltmeter means the test may not work.
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Brian H
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Re: DSC light comes on at 20mph

Post by Brian H »

Glad you got this sorted, well done Jonco for the work with INPA.

Great tip Pingu, I see that the wheel sensors get their ground from the securing bolt, do you need to put the multimeter across the two terminals of the sensor or do you need a ground for reference?
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pingu
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Re: DSC light comes on at 20mph

Post by pingu »

Brian H wrote:Great tip Pingu, I see that the wheel sensors get their ground from the securing bolt, do you need to put the multimeter across the two terminals of the sensor or do you need a ground for reference?
I assume the two wires, but you should really test a good one to find out.

I wonder if the earth connection is to ensure that the trough of the ac voltage is 0v. If it wasn't earthed, could the voltage peak be too high for the electronics in the ECU?

RobertT has more knowledge about these things. I only really understand things I can hit with a hammer, or prod with a stick. Electronics are like black magic to me.
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Tufarlian
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Re: DSC light comes on at 20mph

Post by Tufarlian »

pingu wrote:....you can test a sensor if you have an analogue voltmeter. Connect the two sensor wires to the voltmeter and spin the wheel. If the needle flutters, sensor is working....
Useful to know. Makes it possible to test a sensor without having to remove it.
Thanks
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pingu
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Re: DSC light comes on at 20mph

Post by pingu »

Image

It looks like it is as I guessed. The sensor will be excited by the spinning wheel and it is the two wires that go to the car that should be checked for an alternating voltage. I still don't know what the earth connection is for :shock: .
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Re: DSC light comes on at 20mph

Post by henrycrun »

Still chasing my ABS/DSC lights.

All underbonnet fuses OK, but does anyone know exactly where Fuse 49 is ?
I've looked under panel below the steering wheel but can see only 3 relays. Where is it....
Mike Fishwick
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Re: DSC light comes on at 20mph

Post by Mike Fishwick »

It seems that the car is trying to tell you that everythinhg comes through the initial self-test routine at switch-on with no problems, but a problem is seen at 20 mph when the system goes live, so I doubt if a code reader will throw up anything of interest.

I would bet that both front sensors are pretty grubby by now, and until you can remove and clean them any conjecture is worthless. If that means wrecking the sensors to get them out, so be it - at least it would be a job worth doing, and cheaper than having a garage plug a computer into the car.
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Brian4
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Re: DSC light comes on at 20mph

Post by Brian4 »

henrycrun wrote:Still chasing my ABS/DSC lights.

All underbonnet fuses OK, but does anyone know exactly where Fuse 49 is ?
I've looked under panel below the steering wheel but can see only 3 relays. Where is it....

I can't see a fuse 49 on the Z3 wiring diagram. Where did you get a reference to it from?
Has your car got the DSC button or ASC as the DSC has far more sensors and the ASC really only has the 4 wheel speed sensors and the brake light switch in circuit, and operates through the ABS module to apply brakes as it sees fit

As said above wheel speed sensors can be tested for continuity and is the wheel is spun with a test meter on voltage you should see it change.
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henrycrun
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Re: DSC light comes on at 20mph

Post by henrycrun »

Fuse 49 is listed on my main fusebox cover "located under steering wheel" (Car is a 1.9 built Jan 99)
Just the one ASC button on the dash.
I've spun each wheel with a meter and I 'seem' to get pulses generated all round.

I've also been to to a garage have codes read, but they couldn't get a connection to the car.
Starting to get concerned as the MOT is in 3 weeks...
John Wilson
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Re: DSC light comes on at 20mph

Post by John Wilson »

I agree with Mike that you should just get the wheel sensors out, and if they are damaged, then just replace them for a few quid. At least the bolts are removable and have not sheared, which is the biggest problem. Once out, they can then be easily cleaned on a regular basis, thus preventing future problems. It is the front ones that get the most dirt.
henrycrun
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Re: DSC light comes on at 20mph

Post by henrycrun »

I would swap them out but the fronts are stuck fast.

BTW - does the speedo use ABS sensor pulses and if so, which corner ?
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Robert T
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Re: DSC light comes on at 20mph

Post by Robert T »

Speedo pickup is on the diff, not the wheels.

Cheers R.

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MikeR
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Re: DSC light comes on at 20mph

Post by MikeR »

ECU Testing Ltd in Derby helped me out with ABS/DSC issues.

Robert - I've sent you a pm.

Cheers
MikeR
henrycrun
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Re: DSC light comes on at 20mph

Post by henrycrun »

BTW - do the ABS and DSC lights have the capability to display AMBER or RED depending on the severity of the fault ?
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Robert T
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Re: DSC light comes on at 20mph

Post by Robert T »

Not as far as I know. I did see this on the brake hydraulics light when running some tests on a 2.2 recently, but not on any of the other lights. None of the pre-facelift cars have this.

Cheers R.

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henrycrun
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Re: DSC light comes on at 20mph

Post by henrycrun »

Front RH ABS sensor diagnosed at garage last week.
Just spent 3 hours, on and off with WD40 trying to unstick it. No luck.

Any suggestions ?
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colb
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Re: DSC light comes on at 20mph

Post by colb »

AS its been identified as faulty your only option is to drift it out with a punch and a hammer destroying it in the process, clean the mounting hole up and fit your new one.

Colb
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John Wilson
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Re: DSC light comes on at 20mph

Post by John Wilson »

You could try a proper releasing oil. I believe that The WD40 people do a releasing oil, but that the standard WD40 is not strickly for that use. Try keeping it soaking for a few days. It might save you a few quid distroying the sensors.
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Brian H
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Re: DSC light comes on at 20mph

Post by Brian H »

colb wrote:AS its been identified as faulty your only option is to drift it out with a punch and a hammer destroying it in the process, clean the mounting hole up and fit your new one.

Colb
+1, the hole in the king pin which the abs sensor sits in really does get choked up with corrosion, I removed the front wheel hub/bearing assembly and attacked it from that direction.
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Re: DSC light comes on at 20mph

Post by henrycrun »

Does anyone have a favourite penetrating oil ?

(I only know of Plusgas and WD40)
siwilson
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Re: DSC light comes on at 20mph

Post by siwilson »

henrycrun wrote:Does anyone have a favourite penetrating oil ?

(I only know of Plusgas and WD40)
Good old 3 in 1 and lots of patience. Works pretty much every time.
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Mike Fishwick
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Re: DSC light comes on at 20mph

Post by Mike Fishwick »

Both WD-40 and Plusgas evaporate too quickly - I prefer to use diesel, which will creep through anything.
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Re: DSC light comes on at 20mph

Post by henrycrun »

My tame mechanic swopped out the faulty wheel sensor today - and the blooody ABS+Traction lights are still on.

Is there a reset that has to be done ?
John Wilson
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Re: DSC light comes on at 20mph

Post by John Wilson »

It sometimes takes a couple of journeys before resetting itself. Hope it works.
John
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Re: DSC light comes on at 20mph

Post by henrycrun »

Thanks

In the meantime, I may buzz through for continuity, from the wheel sensor plug to the ASC pump connector.

Can anyone point me towards a wiring diagram that gives ASC pump pin numbers (and colours) for the 1.9 M44 1998 ?
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BladeRunner919
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Re: DSC light comes on at 20mph

Post by BladeRunner919 »

You can download the ETM from here: http://wedophones.com/BMWManualsLead.htm
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Re: DSC light comes on at 20mph

Post by henrycrun »

Correct me if I'm wrong but I can't see any wire colours on those.
In addition the pin #s in the schematic don't seem to match the pin #s in the list.
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Re: DSC light comes on at 20mph

Post by henrycrun »

Had another diagnostic done today, the new wheel sensor is working OK, but now we have
- ABS Pump fault.

Can I just swop this out for an identical unit ? Are there any coding issues ?
Brian4
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Re: DSC light comes on at 20mph

Post by Brian4 »

If you speak to the guys at BBA Reman they are very helpful. As far as I know they don't need coding.

http://www.bba-reman.com/UK/
or
http://www.ecutesting.com/
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Re: DSC light comes on at 20mph

Post by Zed Carer »

henrycrun wrote:Can I just swop this out for an identical unit ? Are there any coding issues ?
I had to have my replacement pump re-coded Details Here. The guy who re-coded it said that each vehicle has a code (IIRC its 34 digits) stored in the vehicle's ECU and this has to be copied to the ASC unit so it knows what other systems the vehicle has fitted. Theoretically if you can get a pump from an identical vehicle then it is possuble that it wouldn't need re-coding as the code should be the same for both vehicles.
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bertiejaffa
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Re: DSC light comes on at 20mph

Post by bertiejaffa »

I still have to take mine off and get it sent away - probably a daft question but how easy is it to get off - If I unscrew the pipes what is going to pour out?
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Re: DSC light comes on at 20mph

Post by henrycrun »

Only brake fluid, just mop up as you go with rags or paper towel.
May want some releasing oil on the pipe unions first.


Just to finish my long winded story.
Received a used Z3 ASC Pump sourced from Spurs Fan (Many thanks!)

I checked that the part numbers matched my existing unit, both on the pump body - and on the integral controller (hard to read without poking a camera into the darkness)

Then got a local garage to fit the unit and bleed the system.
They then cleared the fault codes, ABS and Traction Lights went out (for now!)
Car quickly MoT'ed for another year.
Result !
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Re: DSC light comes on at 20mph

Post by spurs fan in a coupe »

Brilliant

Really pleased that it seems to have worked

Enjoy
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Re: DSC light comes on at 20mph

Post by Cabrioot »

Good job hope its out for ever. :)
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