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

1M views 1K replies 213 participants last post by  MeisterSchnitzelBrau 
#1 ·
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.)


 

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#51 ·
Donna, looks good from a data standpoint. I like 540iman's actual procedure linked with pictures to get to the actual test and resolution DIY.

Lot's of good data in this and other threads which I can see you've consolidated, now I believe the next action is to pull the key, actual test and replacement text with pics.

If you want to take this to the end, Perhaps you and 540iman can tag team to get to a consolidated, focused and effective DIY.
 
#52 · (Edited)
If this were your Carsoft output, what does that mean to you?

Single diagnosis ABS / ASC - Status ERROR !
Module info: ABS / ASC / DSC
Version: Bosch ABS 5
BMW Part Nr. : 6 75 89 71
Hardware Nr: 55
Software Nr: 3.18
Diagnose index: 16
Code index: 10
Bus index: 60
Producdtion Date: 3/01
abs1.dxt
114
 
#53 · (Edited)
Based on the diode test, the assumption now is that the problem is the ABS module.

I have the following four or five options:
0. Should I open up the ABS module and attempt fixes myself?
1. Or go with BBA Reman http://www.bba-reman.com ($225)
2. Or Module Masters http://www.modulemaster.com/en/abs/ate_bmw_asc.php ($105)
3. Or go with a new $450 + $45 tax = $500 rebuild from oembimmerparts.com (a sponsor)
4. Or give up and opt for BMW OEM (at $1,120 + $112 (~10% tax) = $1,232)

I really want to look inside the ABS module. Do you think opening it up will cause the rebuilders to not accept it for subsequent repair?

 
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#55 ·
You are absolutely correct. Yourself and EAC both are right there new. The only bad thing is you will require recoding if you get a new module rather than a rebuild and the NEW Bosch units from what I understand are essentially the same unit they were prior and therefore still have inherent heat sensitivity making a re-built in many cases better than new. Your point is well made. There is not such thing as a "re-build" kit from BMW and those prices are definitely WORST case meaning you stagger into a BMW stealership with a white cane and your wallet out.
 
#58 ·
Before you put down the Carsoft software, don't you feel you should ask carsoft? If your copy is bogus and that is why you are afraid to ask then reach deeper in your pocket and do the right thing. I could ask for you as my copy is legit, but I am not going to enable others to profit off the work by entrepreneurs. Think about it. Are you being fair to the authors?
 
#62 · (Edited)
Ah, this explanation helps. Thanks. Sorry for not knowing this ahead of time. This errant sensor reading might be the reason some people replace sensors and the ABS module yet still have the three warning lights lit.

It seems there is a "pressure sensor" P/N 34511165467 $111.68 screwed into the back of the hydro unit in the engine compartment of the 2002 E39.

I wonder what an "offset" error indicates?

Any advice how to test this ABS hydraulic unit "pressure sensor"?
 

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#65 ·
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!
 
#66 · (Edited)
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!

 

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#67 ·
Looking at the front brke pressure sensor at the rear of the hydro unit, I see the brake pressure sensor harness has three wires that we can tap into to test live voltage.


I did notice some "stuff" on the edge of the clip, so I cleaned that off and reconnected the clip.


I don't know if it's related but the problem still shows up as three lights lit on the instrument cluster ... but now ... it seems, the problem has "moved from:
114
to:
81 Einlassventil : vorne links

Which, in English, appears to indicate:
81 Inlet valve front left

But, Error 81 in the posted Bosch 5.7 codes appears to be:
81 Pressure Sensor

Are these the same thing? Or different?
 

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#68 ·
I don't know if it's related but the problem still shows up as three lights lit on the instrument cluster ... but now ... it seems, the problem has "moved from:
114
to:
81 Einlassventil : vorne links

Which, in English, appears to indicate:
81 Inlet valve front left

But, Error 81 in the posted Bosch 5.7 codes appears to be:
81 Pressure Sensor
Are these the same thing? Or different?
The way Carsoft works with my 530, the error code is accurate, but my descriptions are wrong, at least on the DME side.

If you did test for voltage at the pressure sensor with the ignition disconnected, then it makes sense that the module would throw a "pressure sensor" code, as it did not see the pressure sensor.

Plug the sensor back in, and reset the ABS module. I don't think the "81" will come back.

To test the output voltage, you could make up something like this: http://www.picoauto.com/breakout-lead.html
 
#72 ·
Bluebee, why are you making this more difficult than it is? Start the car or turn the key to position#2. You don't need an adaptor or any tool! You can strip a tiny bit of insulation away from each of the three wires if it is easier than to just back-probhe into the connector. Attach your ground VOM wire to any good ground- use the strut tower nuts. Take the remaining positive meter lead and test each of the three wires one at a time. One will read 0.0, one will read approx. 5.0 VDC, and one will read somewhere less like maybe .5 VDC or somewhere close. Then, start car and have someone press the brake pedal while you observe the wire voltage that was less than 5.0VDC. This will be the follower voltage. That's all there is to it..
 
#73 ·
Bluebee, why are you making this more difficult than it is? Start the car or turn the key to position#2. You don't need an adaptor or any tool! You can strip a tiny bit of insulation away from each of the three wires if it is easier than to just back-probhe into the connector.
That is one way, but if you live where they use salt on the roads, the bare copper will corrode very fast and may give you more trouble down the road.
 
#75 · (Edited)
Just by way of datapoints, the current code is no longer Bosch 114 (Pressure Sensor) but is BMW 81 (Inlet Valve, Front Left).

It's confusing to me that two different decoding systems are needed, but, that's what it appears to be (Bosch & BMW).

It's also confusing to me that the first error (front brake pressure sensor) doesn't seem to be related to the second error (front left inlet valve, whatever that is).

As another datapoint, since I worked on it this weekend, the three yellow warning lights have taken MUCH LONGER to light up (ten or fifteen minutes sometimes); and they seem to flicker on and off while I'm driving. Before, the three orange warning lights went on within a couple of minutes and stayed on.

I'm beginning to think it might be the ABS module after all ... which might explain the inconsistencies as it "tries" to sense information from the twenty or so inputs that it has to work with.

I'll keep an eye on it and test further, given your advice. Meanwhile I'm looking around in hardware & electronics stores for that tiny 1/2 mm square female connector that is the most important one to find. You'd think in the Silicon Valley that would be easy to find ... but not yet.

I'm going to try the following local connector companies:
- Molex over in Milpitas (920 Hillview Ct, 408-946-4700)
- JDR in North San Jose (1723 Rogers Ave. Unit O, 408-392-0100)
- JAE in Santa Clara (5201 Great America Pkwy # 320, 408-562-6003)
- Dicar in San Jose (1285 Alma Court, (408) 295-1106)

Does anyone know the "specifications" of that particular male-female square washington-monument shaped male pin?

It looks like the pressure sensor connector male posts are little washington monuments about a half millimeter by a half millimeter in square size and about a half inch long. It seems to be the same connector that is on the ABS connector. Does anyone have a spec for this that I can fax to the companies above before I stop in?

 

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#76 ·
Good luck bluebee! I no longer can help and I am lost as to what you are trying to accomplish. When it was the pressure sensor, I was with you and trying to help you get a reading from the sensor itself, but it seems like you have it well under control. I'll check periodically to keep learning myself.. G/L, I know your postings have helped many immensely.
 
#77 · (Edited)
I am lost as to what you are trying to accomplish
Thanks. You've been an immense help already! Much more than most!

Since this isn't an emergency, I have the luxury of attempting two things at the same time:
1. I'm trying to compile a good ABS DIY (with your help) so others have an easier time than we did
2. I'm trying to diagnose the cause of the problem (for myself, and for others to benefit from the diagnosis procedure)

For item 1, I don't mind doing a bit extra work (notice all the work annotating the pictures and editing the DIY for others). That's not for me. It's for others. With all your help, we can help others with this DIY.

For item 2, here's my current plan:
a) Continue to monitor the error messages with diagnostic tools (unfortunately, the errors seem to change over time)
a) Identify what is the purpose of the left inlet valve & where is it located (I called the local dealership and they never heard of it)
b) Choose how to test the pressure sensor (either strip the 3 wires or build a jig; I prefer to build a jig if I can - it's more graceful)
c) Test the left inlet valve ... if bad ... replace (bearing in mind it may be part of the hydro unit)
d) Test the pressure sensor ... if bad ... replace (bearing in mind a $100 test jig for a $100 part isn't feasible)
e) If both the inlet valve & pressure sensor test good ... rebuild ABS control module (thiis is probably where I'm gonna' end up anyway)

Does this sound reasonable as a test plan?

(I know most people would say "just skip to the last step"... and I'm fine with that as an end result ... but from a diagnostic standpoint, all indications currently are that it's a sensor, not the ABS control module).

 

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#80 ·
Oh my! You're wonderful! That looks perfect! And cheap!

I already determined a 20 AWG wire would fit into those tiny square holes.

I might even buy 42 of them to make my own ABS connector breakout box so we can test the entire ABS system in situ!

I think I'll order 42 (for the ABS connector) plus 3 (for the brake pressure sensor) plus a few extras (just in case).

 

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#79 ·
You all lost me back at post #68. If the pressure sensor is at all an issue, it should be tested right at the connector for the three wires going into it. If two or three folks compare what their readings are without any brake pressure and with a firm depression of the pedal, I would think we could tell if there was enough of a difference to be an issue. The measurement should be taken with the car running and the trailing wire (of the three) identified. The reading would be from this wire to ground and done by using a "piercing" probe on the VOM set for VDC.

Beyond that, I am lost. I do not follow what you are trying to read at the module pins themselves. I can only speak from my personal experience, but I found ATE1234 (Auto & Truck Electronics) on Ebay to be a very good value as a re-builder of modules. Don's (the pres. of ATE) price of $105 for a rebuild with a lifetime guarantee is the least I have seen and he tests every module before rebuilding to see the "as-received" condition. He is even good about letting you speak with the tech. that works on your module after-the-fact if you would like to know what they found once they split your module open.

Beyond this I can't help you guys. I applaud the spirit of taking a thorough and logical approach such as you have been. It just seems at some point you lack the data you need to go much farther and that is where an ATE comes in. G/L
 
#81 · (Edited)
Does anyone know why the ABS connector has two holes for every pin?

Notice that the ABS connectors have two holes for every washington monument (with the exception of the extra-wide pin #1 and pin #2).

Does anyone know why there are TWO holes for (almost) every pin in the ABS system (the square one being MUCH smaller than the rectangular neighbor).

I wonder if the square one (smaller than 20 AWG) is for the monument while the larger rectangular one is for the test wire (I used 20 AWG, which would deform the smaller square holes).

 

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#83 · (Edited)
I think I misled you with the wording of my question.

From your answer, I deduce you're explaining the six larger wider rectangular pins and corresponding holes numbered #1 to #6. But I wasn't talking about those first six pins since the only ones that matter at the moment are the sensor pins which aren't any of those first six. (So it's my fault for not making the question clear).

To restate the question, notice there are 36 other pins that are all of the same size; these are pins #7 to #42. These 36 other pins actually have twice as many holes as there are pins. Each of those 36 has both a square hole (which the Washington-monument-like pins go into); and there is a slightly larger concomitant rectangular hole right next to each square hole.

Why? What's the second hole for?

I think the answer is:
1. The first (tiny) hole (square) is for the tiny pins (washington monuments)
2. The second (larger) hole (rectangular) is for the (probably round) test leads.

If so, BMW designed this connector rather well; they gave us a test point that is not the same as the connection point.

If this is true, we should tell everyone, moving forward, that they should stick their 20 AWG test leads into the test-lead hole and not into the pin's square hole. If they stick their large test leads into the wrong hole, they may deform it and damage it (my assumption), which would be a bad thing. I think that's why BMW supplies the test-lead hole. (My guess).

So, if I'm right, we now have a hint and a warning for the next person who attempts to test their ABS sensors from the ABS connector.

Right?

 

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#84 ·
Bluebee, I believe he understood your question. You may not have understood his answer. I think it is irrelevant, but the second hole by each pin is to allow more surface area on the other side for the small pin is his guess. I do not think he is referring to the 6 slotted holes. It is some sort of "clearance" hole is his guess.

This thread is jumping around so much I think you are going to lose readers. You had a pressure switch issue- then you didn't, but you never tested your switch and I don't know how you decided to discount it.. I tested mine and it clearly is very straightforward and easy to test on the car by back probing (sticking the VOM leads into the backside of the connector). What we will never know is what rise in voltage is necessary for the module's brain to be happy. Mine swung up to just a hair over 4 VDC with full brake pressure. it was about .4VDC with no brake applied.
 
#85 · (Edited)
Mine swung up to just a hair over 4 VDC with full brake pressure. it was about .4VDC with no brake applied.
OK. Let's get back on track. This thread is about two things:
1. How one would, in general, debug ABS issues (mostly this updated post)
2. My particular saga (which follows & updates the diagnostic procedure in #1 above)

MY SAGA:
- ABS/BRAKE/DSC lights are still lit (so I have not solved anything yet)
- All four wheel sensors tested good (thanks 540iman for the definitive tests!)
- Diagnostic tools first indicated a Bosch "114 Pressure Sensor Offset"
- Now they implicate a BMW "81 Einlassventil : vorne links (inlet valve, front left)"
- I ordered the pins to test the brake pressure sensor (but I don't think it's that anymore 'cuz the diagnostic tools no longer implicate it).
- Nobody seems to know what an "inlet valve, front left" is, let alone how to test it.

MY PLANS:
- I plan on testing the brake pressure sensor and reporting the results (thanks for your comparison results!)
- I hope to locate the "inlet valve, front left" and test it (somehow)
- If both test good, I plan on sending my ABS control module out for a rebuild

So, the main unanswered questions is ...

QUESTION:
What is an "inlet valve, front left" and how does one test it?

NOTE: I'm googling for the following and tracking down the references:
"inlet valve, front left" bmw abs

It looks like it might be an abnormal solenoid valve circuit(s) in the ABS control module or hydraulic unit. Apparently test voltage must be 0V with valves off and 12V with valve on (the inlet and outlet valves are active for short times only during ABS modulation).
 
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#86 ·
I would think that it has to be part of the module itself
The more I look this up, the more I think you're right that it's the ABS module masquerading as a series of red-herring errors.

For example, this BMW Bosch 5.7 error resolution says "Inlet/Outlet valve" fault codes could actually indicate a bad ABS control module (having nothing to do with the inlet or outlet valves themselves).

But, if it is actually the inlet valve, it must be inside the hydro unit based on this description of the hydro unit:

The hydraulic unit consist of an aluminum block containing 12 solenoid valves, 2 pressure accumulators and the return pump.
• 4 inlet solenoid valves (normally open)
• 2 changeover solenoid valves (normally open)
• 4 outlet solenoid valves (normally closed)
• 2 intake solenoid valves (normally closed)

What scares me, if the solenoid valve is actually bad, is it apparently is required to ensure normal braking is possible in the event of a defective control unit. So it's important to locate and test these solenoid valves.
 
#87 ·
Yes, I think you're right on both accounts. The valve itself would be inside the aluminum block and virtually impossible for a lay person to test. There is a spool inside that shifts when voltage is applied to those coils that "hang off" the electric-side of the module. Coils set up a field that pulls the spool one way or another. The question then becomes "is the valve itself actually not shifting" or "is the valve shifting properly and the module just does not recognize it"?

Still don't know what software you are using, but suspect you are close to done unless you can build a test set-up to check the module. It becomes a matter of economics at some point. You will always have that question of is an input to the module not there or is it there and the module just can't sense it.
 
#88 · (Edited)
You will always have that question of is an input to the module not there, or is it there and the module just can't sense it.
Hi 540iman,
I agree.

At this point, we're far past what most other people would have done:
- We've read every single bimmerfest post on the subject
- We've scoured the Internet for additional E39 Bosch 5.7 ABS troubleshooting advice
- We've combined all this and documented the entire procedure in a single post
- We've included everyone's advice that has been offered to date
- We've added plenty of E39 specific pictures (for the newbies, which I used to be just a month ago)
- We've answered everyone's questions as best we could (and we'll continue to ask questions)
- We've analyzed options and we've come to the same final conclusion as everyone else ...
etc.

In the end, I think you're right. Despite the fact that Carsoft 6.5 keeps reporting anything but the ABS control module, the anecdotal evidence seems to implicate the ABS module itself.

I have no problem with the money to rebuild my ABS module. I just don't think I'm done with the diagnostic steps yet. For example, I'm still not sure if I can GRACEFULLY take apart the ABS module to look inside and perhaps even to snap a few photos of it's inner working parts before sending it out to the rebuilders to fix.

At this point, I plan on:
a) Testing the brake pressure sensor (but I really don't expect it to be bad)
b) Give up on testing the "inlet valve, front left" (because it's inside the hydro unit)
c) Seeing if I can gracefully open up the ABS control module (for a living autopsy)
... and, after that ...
d) Sending it out for a rebuild (if I haven't destroyed it by opening it up first)

Meanwhile, I'll take almost all the advice given here and report back the results for others to benefit from who don't have to read hundreds of threads to get where we are today ... they can just print and read this one.

QUESTION:
Has anyone here ever opened up their ABS module gracefully and then sent it out for a rebuild?

Does anyone know for sure the rebuilder will take it after I've dremeled off the cover?
 

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#89 ·
Is the fuel gauge REALLY tied to the ABS system? How? Why?

I sporadically run into anecdotal evidence that the fuel gauge is tied to the ABS unit operation but I can't, for the life of me, understand why that would be.

When I look at the wiring diagrams for the Bosch 5.7 ABS system, I see no connection to the fuel gauge.

And, I don't see why wheel, yaw, steering angle, or brake-pedal and brake-pressure sensors that are tied to the ABS would have anything to do with the fuel gauge.

Yet, there is ample sporadic evidence that the fuel gauge sometimes goes haywire when the ABS system does.

How can that be?

What possible connection is there between the ABS and the fuel gauge?

 

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#149 ·
That is what I did...

This is what I did. I had my mechanic pull my ABS module. It was sent to BBA Remanufacturing (http://www.bba-reman.com/us/index.aspx) and they fixed it in one day. It cost me $320 and $50 to ship it FedEx and back. I drove a week with no ABS and all the crazy stuff. I just made sure I kept my tank full. We plugged it back in today and no lights are on. It is all good!

---------

I sporadically run into anecdotal evidence that the fuel gauge is tied to the ABS unit operation but I can't, for the life of me, understand why that would be.

When I look at the wiring diagrams for the Bosch 5.7 ABS system, I see no connection to the fuel gauge.

And, I don't see why wheel, yaw, steering angle, or brake-pedal and brake-pressure sensors that are tied to the ABS would have anything to do with the fuel gauge.

Yet, there is ample sporadic evidence that the fuel gauge sometimes goes haywire when the ABS system does.

How can that be?

What possible connection is there between the ABS and the fuel gauge?

 
#90 ·
There are other re-builders for less not mentioned BTW. ATE (ATE1234 on Ebay) charges $105. I do not believe the fuel gauge is tied to the ABS module per se', but the fuel useage system is. It needs inputs from the speed sensors just as the speedometer/odometer do to calculate fuel usage and fuel remaining. I believe it is the fuel remaining calc. that gets so jacked up by levels being sent from the fuel gauge, but no input that mileage is being put on the vehicle but fuel is being consumed with no speed sensor output. There is a lot of incest between the BMW systems; they share inputs and look at each other for confirmation they are ok.

The reason for the yaw sensors and angle sensors being tied-in is because the Dynamic stability control uses them. The DSC uses the ABS system to do its thing. ABS and DSC work in tandem-if one is sick, the other has sympathy pains.
 
#91 ·
Where (else) does the E39 obtain mileage information?

I do not believe the fuel gauge is tied to the ABS module per se', but the fuel useage system is. I believe it is the fuel remaining calc. that gets so jacked up by levels being sent from the fuel gauge, but no input that mileage is being put on the vehicle but fuel is being consumed with no speed sensor output.
That makes sense that the fuel-usage system needs to know the mileage, and, since the mileage comes from the left rear wheel sensor, that the fuel-usage system gets "jacked" up.

But the fuel-remaining gauge is just a potentiometer, right? It should just show the level of fuel, no matter the mileage (otherwise emptying or filling the tank with fuel would screw it up).

Anyway, I do understand that the fuel-usage system may need the left rear wheel sensor so maybe that's what everyone is talking about when they (erroneously?) say the fuel gauge started acting erratically when they removed their ABS module.

The reason I care is that I'm trying to write a definitive DIY for troubleshooting, taking into account everyone's input (including a LOT of yours 540iman!) ... and ... well ... the erratic fuel-gauge reports don't seem to fit my model of what is going on.

While the ABS module is off the car for rebuild, another good point you brought out in your related post was "your odometer and your internal mileage tracking will disagree the longer you have no odometer. I do not know how far the two can differ before you throw a code that you may have a real hassle resolving."

I wonder if anyone has more details on this potential problem of conflicting mileage with the ABS module removed?

QUESTION:
- Other than the left-rear wheel speed sensor, where else does the E39 obtain mileage information (which would be out of whack)?
 
#92 ·
Bluebee,

Agree 100%. The fuel gauge in every car I have come across is nothing more than some sort of float and a potentiometer. So, in theory the ABS/DSC/speed sensors should have no effect on the fuel gauge accuracy. If I can take the comments made by others verbatim, somehow the fuel gauges that are otherwise accurate seem to become unreliable for some at the same time they get the dreaded three lights of doom (Abs,dsc, brakes). My comments are a vague and lame attempt to somehow explain the phenomena. I know of no correlation between the two systems, but since many claim it does happen, I am trying to reverse explain some type of plausible "possibility". I think I am either close to explaining it OR there is no correlation and it is just coincidence.
 
#93 ·
in theory the ABS/DSC/speed sensors should have no effect on the fuel gauge accuracy
Let's just keep an eye on the threads so when the next person notices the fuel gauge becoming flaky along with ABS, we can ask them to confirm it at that time.

BTW, this recent posting is a fantastic ABS/DSC module autopsy (with a large zip file of detailed pictures).

I'm still very unsure of how to take apart the module to look inside (I very much am curious as to the condition of the solder joints).

Any additional suggestions as to how to take the ABS module apart?
Also, do you think the rebuilders will take it once it has been opened?

 

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