2002 E39 ASC BRAKE ABS lights on => Diagnostic Procedure & Parts Location

Oh my. My 2002 BMW E39 has these three lights lit on my instrument cluster:
- Triangle (is it ASC or DSC?)
- Brake
- ABS

I see there are lots of threads on this so I'm reading through them, but, they all seem to know already if it's ASC or DSC they're dealing with.

Am I dealing with ASC or DSC?

ASC (automatic stability control) apparently senses 4-wheel differential speeds during cornering and cuts the engine power via a second throttle butterfly valve to help keep you from oversteering and spinning out in wet/snowy/unfavorable conditions. It may also apply the rear brakes lightly in some situations. It apparently doesn't touch the suspension at all. It has been described as ABS in reverse. Reputedly, while ABS controls the braking force at all four wheels, ASC + T controls the power delivery of the engine, and the way the rear differential distributes torque between the two back wheels only.

DSC (dynamic stability control) in contrast, is apparently a suspension-control system which goes beyond Automatic Stability Control + Traction by monitoring steering wheel movement, vehicle speed, transverse acceleration and yaw to register imminent instability when cornering. DSC then intervenes via the engine management system reducing drive torque and activating wheel brakes when necessary to keep the vehicle stable.

Having said all that, how do I know if my 2002 E39 has ASC or DSC?
(I think it's ASC but I need to know before beginning my troubleshooting.)

Your 525 is 2002 which has the DSC. If I recall correctly the ASC is on the 1997, 1998 E39 US models.

Originally Posted by NFS

Your 525 is 2002 which has the DSC.

Thanks.

It's weird, but, for the past three days, sometimes the three triangle/ABS/Brake warning indicators are on, other times only the two ABS/Brake indicators are on, and other times none are on (see photos below).

I wonder if this problem is related to the fact I've been constantly disconnecting my battery to reset the DICE iPod interface.

Have you tried the warning light reset procedure?

Normally when you've got all those lights lit up, it's a problem with the DSC module.

Originally Posted by Elvis530i

Have you tried the warning light reset procedure?

I'm still in the "research" stage... trying to find the canonical DSC/ABS CEL brake troubleshooting thread.

In summary, after reading some of the many threads...

Is this the DSC/ABS/Brake warning indicator diagnostic procedure?
- Determine what is being displayed to me (I'm in this stage)
- Understand how the system works (sensors tied to modules tied to lamps)
- Locate the sensors (4?) and associated control modules (2?)
- Read the ABS CEL OBDII error codes with the Carsoft 6.5.1 hardware
- Reset the ASC/ABS/Brake warning indicators & test the car
... If the problem re-occurs ...
- Determine if the problem is in the sensors, and if so, which one(s)
- Determine if the problem is in the modules, and, if so which one(s)
- If modules, decide whether to fix the module & reprogram or buy new
- Install new (or fixed) sensors or modules & test the system again

Is that the basic diagnostic procedure for DSC/ASC/ABS CEL warnings?

You may want to consider BBA Remanufacturing. They could not fix my unit, but they will honor the warranty and they have great customer service. My indy now is saying that the problem is the "precharge unit," whatever that is. I'm undecided about fixing it--he quoted me $850. My ABS works fine and only my DSC light remains lit.

Originally Posted by bluebee

I'm still in the "research" stage... trying to find the canonical DSC/ABS CEL brake troubleshooting thread.

In summary, after reading some of the many threads...

Is this the DSC/ABS/Brake warning indicator diagnostic procedure?
Skip this step- Determine what is being displayed to me (I'm in this stage)
- Understand how the system works (sensors tied to modules tied to lamps)
Move this down to after you've read the codes- Locate the sensors (4?) and associated control modules (2?)
- Read the ABS CEL OBDII error codes with the Carsoft 6.5.1 hardware
- Determine if the problem is in the sensors, and if so, which one(s); replace the sensors
- Reset the ASC/ABS/Brake warning indicators & test the car

... If the problem re-occurs ...
- If modules, decide whether to fix the module & reprogram or buy new
- Install new (or fixed) sensors or modules & test the system again

Is that the basic diagnostic procedure for DSC/ASC/ABS warnings?

Fixed
Short answer is that either you've got an intermittent issue one or more parts, or you need a new module. Probably both….

Even after a full-fledged DICE battery reset procedure, I still have the DSC ABS BRAKE lights going on after a while of driving.

So, I'm gonna Carsoft the thing this weekend and let you know the codes so you can help me better.

One problem (a good one, I guess) is there is a lot of information about this problem scattered about - but I haven't found the one jewel of a thread (maybe we can make this one that so others benefit from our efforts).

Donna

When my ABS module failed those 3 lights would come on and then off when I shut down the car. The lights would come back on again after a little driving. I always got 3 lights thou.

Originally Posted by NFS

When my ABS module failed those 3 lights would come on and then off when I shut down the car. The lights would come back on again after a little driving. I always got 3 lights thou.

Same here. They'd go off sometimes, and then back on again a while later, but I'm pretty sure it was always all 3 lights. Of course, on my car I had the extra bonus that whenever I'd turn on the headlights, or the stereo up really loud, I'd get the transmission going into failsafe mode. I basically couldn't drive the car at night. That was related to the ABS module, as well (not enough eletrical current at the transmission control module).

If it is your ABS module, I'd recommend Module Master. They're also on Ebay under Circuit Solutions. They fixed mine and I think it cost me $325 including return shipping. They also provide a 5 year warranty on the repair.

Short answer: your module's shot and/or you need new sensor(s).

Based on the fact that it's intermittent and you've been fooling with the battery (I'm assuming the DICE install doesn't require you to get into you wheel wells or the steering column), it's the module. If you want to be sure, get the BMW STEALER (i.e. the guy with the expensive computer) to read the codes. Few aftermarket readers can.

What's the display going on about? Detached? Is that the DICE? Also, bloody cold in NorCal apparently!

Edit: It's possible to fix the module yourself, in some cases, apparently. Volvo owners have been doing it for a while. If you're handy with a soldering iron and have a vise and Dremel or hacksaw, you could try fixing it yourself. However, this assumes that you have chip creep with fully functional chips, rather than blown chips and solder in good shape.

Originally Posted by bmw_n00b13

Short answer: your module's shot and/or you need new sensor(s).

I know. I know. I hope to figure out the diagnosis procedure and document it in this thread (if it's not fully documented elsewhere).

My first task is to find a picture of the module and sensors (I think the sensor picture will be easy ... I might even already have one from my brake job - but where is the ABS module location in the engine bay?

get the BMW STEALER (i.e. the guy with the expensive computer) to read the codes. Few aftermarket readers can.

Do you think Carsoft 6.5.1 can read these codes correctly?

Detached? Is that the DICE?

Yes. Detached means the iPod isn't hooked up to the DICE at that moment I snapped the photograph. Otherwise the song name and artist would be displayed on the instrument cluster.

bloody cold in NorCal apparently!

Yea. It was "freezing" here in San Jose this morning. 60 degrees F at 6am at 60 miles per hour when I snapped that shot of my display. Brrrrrrr....

you could try fixing it yourself.

It may come to that. I don't mind purchasing whatever tools I need; it's what I do to get to the bottom of things.

What is the mysterious BMW OEM "repair kit" for the ASC control unit?

After a week now, I can report that I don't have the symptoms of intermittent speedometer but I do have all three DSC or ASC, ABS, & BRAKE lights lit on my instrument cluster after a period of time after I start the 2002 E39, so it's looking like either the 4 wheel-speed sensors or the ABS module itself.

If it's the ABS module itself, it looks like REALOEM lists it as:
E39 525i ASC hydro unit/control unit/support
01 Hydro unit ASC 34516756341 $2,003.22
02 Repair kit, control unit ASC 34526756343

Do you know what this BMW OEM "repair kit" is? It's not mentioned in the ABS fix DIY which says it can be repaired by these two companies:
1. Module Masters
2. BBA Remanufacturing

So, I ask, what is this BMW OEM repair kit anyway?

Also, do we have self-repair instructions handy (the bimmerfest search button is broken - it constantly reports "connection to three.performanceix.com:3312 failed".

Since nobody on Bimmerfest knew the answer, I called the local dealership who said that nobody ever buys the #1 thing called "Hydro unit, ASC"; he said everyone buys the #2 thing called "repair kit, control unit asc".

Prices out the door at the California dealership for parts are:
- #1 Hydro unit, ASC ===> $2,775 + $277 (~10% tax) = $3,052
- #2 Repair kit, control unit ASC ===> $1,120 + $112 (~10% tax) = $1,232
- 2x sensors front ===> $134 x 2 = $268 + $27 (~10% tax) = $295
- 2x sensors rear ===> $201 x 2 = = $402 + $40 (~10% tax) = $442

Is this the sum total of "suspect" parts?

Or is there an "ABS CONTROL UNIT" that we also need to look at?

- #1 Hydro unit, ASC ===> $2,775 + $277 (~10% tax) = $3,052
- #2 Repair kit, control unit ASC ===> $1,120 + $112 (~10% tax) = $1,232
- 2x sensors front ===> $134 x 2 = $268 + $27 (~10% tax) = $295
- 2x sensors rear ===> $201 x 2 = = $402 + $40 (~10% tax) = $442

Does anyone have a set of PICTURES of each of these parts in an E39?

Originally Posted by bmw_n00b13

Short answer: your module's shot and/or you need new sensor(s). This is rather obvious

Based on the fact that it's intermittent and you've been fooling with the battery (I'm assuming the DICE install doesn't require you to get into you wheel wells or the steering column), it's the module. .

How do you reach this conclusion? Resetting the dice at the battery has Zero to do with the module. Please don't speculate.

Im going to be doing my rear drivers sensor (hopefully) tomorow. I will upload some pics to this thread then.

Yes that is the control module, thats were its supposed to be.

Hello all,
I replaced the LCM on my 97 E-39 sedan with one I picked up at a salvage yard. All of my lights are now working fine. The tamper dot came on as the replacement part was from another vehicle. My concern, is this tamper dot something I need to be concerned with as I'm about to hit the road for vacation about 1600 miles and is there danger of harm to other systems on my vehicle.
Took it to a indy shop to have it coded they came up with the fault code indicating the mismatch.
Help please!!!!!!1

Yes, that's the module, there are 6 torx screws I believe.
Bluebee or anybody else; Do you happen to know how are the abs pulse generators supposed to read? I took both of my front ones off the wheel and they both go to infinity (open) when read, I tried different scales just in case I'm loosing my mind. I thought they were supposed to read something like 4 MOhm. If that's the case, then both left and right fronts are gone on my car. I also have the nice tro of amber lights...

I had success, but it likely cost me $105 for a module re-build that I didn't need. After getting the three lights of death, I just flipped a coin and sent the module off to ATE for a lifetime guarantee rebuild. They advised they would test it first, but rebuild it even if it checked "ok" as the heat will get it sooner or later. Got it back and the errors were still there. Did the "diode test" and 3 wheel sensors showed just fine and the front passenger was open-clearly bad. Replaced it for $65 from AutoHauz and all is good once again. Don't even need to clear the error. It clears itself.

the car on the right in the pics above must be a UK car or a mirror image :\…...unless they flipped the washer tanks around too.

No harm will come to your car if you drive with the tamper dot, but it's going to be difficult to sell the car. The dot's there to prevent sale using false weights and measures. Preferably make a new thread if you have an unrelated question.

Can it be possible or I should say likely that one of these reputable rebuilders test a Bosch 5.7 unit after repairing it say it tests fine when in fact is still causing these warning lights to stay on?

Here is my thought on testing the sensor...
Since the output has a range of 0-5volts and it measures pressures from 0-250bar we can figure out the scale of the output:

250 bar = 3,626 psi
3,626 / 5 = 725.2 psi/volt or 1.3 mV per psi.

With the ignition on, measure the voltage on the pressure sensor while someone is pressing hard on the brake pedal.
My guess is that should create about 3,000 psi of force and should show around 4.13 volts. At rest it should show very close to 0 volts.

Good luck!

Hi Max_VQ,
Your input is a fantastic addition to the DIY we're creating to help others who follow in our footsteps! Thanks.

While, I was hoping for an "off the car" static test of some sort, I'll do whatever I can & report back. I do have the Bentleys but I just can't find my electrical volume II. The hardest part, I think, will be to access the signal while the components are attached to the car.

Do you or 540iman know the pin numbers on the ABS connector for the three pins are (power, ground, signal output)?

BTW, your math seems perfect. Witness this Corvette Bosch 5.3 description whose math jives with your estimates quite nicely!