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

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.

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

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?

Rebuilding is always a option but we sell the new bosch unit for 450.00 so I would not use the 1K+ figure in your choices.

Originally Posted by oembimmerparts

Rebuilding is always a option but we sell the new bosch unit for 450.00 so I would not use the 1K+ figure in your choices.

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.

Originally Posted by 540iman

Did you replace the sensor you found had a goofy reading? I thought I recalled you found a bad one???

Well, all four sensors tested similarly. Here are my results. Notice that the forward bias drop of the hall-effect sensors is higher than what a pure diode would be but they are consistently higher in all four wheels.

So I assume that the sensors are good. I should do the voltage and resistance check with the wheels spinning to double check the results though.

Originally Posted by bluebee

Apparently Carsoft can't read OBDII codes but it's supposed to tell me the actual trouble spot but, I guess nobody has the experience to figure out what it is telling us. Sigh. I guess I give up on Carsoft; it turned out to be a total waste of time.

Just a few points:

- On our BMW's OBD is only for emission related systems.
- Carsoft told you the error ABS error code (114) and the version # (Bosch ABS 5)
- I would re-solder any bad solder joint. I can't count the number of things I have fixed just by doing that. You have nothing to loose.
- Here is a list of Bosch 5.7 error codes:

BMW ABS/ASC module - Bosch 5.7

If you experiencing problems with your ABS/ASC and you have Bosch 5.7 electronic you can check the following codes. This Bosch electronic module have problems with engine heat and after some time felts. You can use Carsoft or INPA to check your car.

List of error codes:

5 Right Rear Wheel Speed Sensor
6 Right Front Wheel Speed Sensor
7 Front Left Wheel Speed Sensor
14 Solenoid Valve Relay (check fuses 17 & 33)
15 Pressure Sensor/Pump Error
21 Module Memory Failure - ABS/ASC module is faulty
23 Incorrect Coding - ABS/ASC module is faulty
24 Wrong Impulse
30 Left Rear Wheel Speed Sensor
31 Open Right Rear Wheel Speed Sensor
32 Open Right Front Wheel Speed Sensor
33 Open Left Front Wheel Speed Sensor
50 Right Front Outlet Valve - ABS/ASC module is faulty
51 Left Rear Outlet Valve - ABS/ASC module is faulty
54 Left Front Inlet Valve - ABS/ASC module is faulty
55 ASC Intake Valve - ABS/ASC module is faulty
58 Gear Box Control Unit (CAN bus error)
59 DMER1 (CAN bus error)
61 Steering Angle Sensor Identification
66 Speed Sensor Voltage Supply
67 Intermittent Interference
75 Engine Speed Fault from DME
81 Pressure Sensor
82 Open Yaw Rate Sensor
86 ASC Cut-off Valve Rear Axle
88 Precharge Pump
89 Low Voltage
90 Temporary System Deactivation
94 DDE Fault/Yaw rate sensor
97 Steering Angle Sensor
10 Brake Light Switch
108 SN Control
112 Open CAN to Instrument Cluster
114 Pressure Sensor Offset
117 Brake Light Switch Failure
118 DME Status-Internal Error

I don't know if Bosch 5 codes are different from Bosch 5.7, but I would think they would be the same.

Keep up the good work

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?

Originally Posted by Max_VQ

don't know if Bosch 5 codes are different from Bosch 5.7

Oh my! Thank you. I apologize. I didn't realize the information was right there ... under my nose. I just didn't understand what I was seeing! I admit my ignorance (as if I could hide it). Sorry. But thanks for pointing it out. This will help others too so it's useful to go a step deeper if we can....

On the modulemasters web site, for a 2002 525i, they say it's a Bosch 5.7 so I think your list of error codes is the correct list.

114 Pressure Sensor Offset

Hmmm .... Which pressure sensor? We haven't covered "pressure sensors" in detail yet. I presume it's a hydraulic pressure sensor. Maybe to monitor how hard we're pressing on the brakes? Would that sensor be in the brake master cylinder or on the ABS hydraulic unit?

QUESTION: Do we have a test sequence to locate and identify a bad "pressure sensor" (wherever it is)?

There is a pressure sensor mounted right on the back of the manifold behind the solenoids. Wonder if connections are loose or bad sensor?

Originally Posted by bluebee

On the modulemasters web site, for a 2002 525i, they say it's a Bosch 5.7 so I think your list of error codes is the correct list.

I would trust what Carsoft shows and not what the MM web site shows. On the E39 we have many different versions of ABS. See the attached pic.
(data from page 7 of http://www.carsoftinternational.com/...20Overview.pdf

[edit] Does your module look like any of the ones here: http://www.modulemaster.com/en/abs/all_modules.php

I think you may have 5.7... More good reading in the attached PDFs.

Originally Posted by 540iman

There is a pressure sensor mounted right on the back of the manifold behind the solenoids. Wonder if connections are loose or bad sensor?

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"?

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?

Originally Posted by Max_VQ

I think you may have 5.7... More good reading in the attached PDFs.

Your documents are FANTASTIC to help me understand the system!

All cross referencing indicates I do have the Bosch 5.7, including those references in the documents you posted which explain how the whole Bosch 5.7 ABS/DSC system works with the sensors.

Others will benefit also! One way, if we can figure it out how to do it, to test this front-brake pressure sensor would be to do a "flying lead" while the car is running to see if a 0 to 5 volt signal is generated while using the brakes.

But, it would be easier to do a static test of this front-brake pressure sensor with the car ignition off from the ABS module connector.

Do you have any ideas how to test the "offset" of the front-brake "pressure sensor" that is screwed into the rear of the ABS hydraulic module.

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!

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?

Originally Posted by bluebee

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

Originally Posted by Max_VQ

The way Carsoft works with my 530, the error code is accurate, but my descriptions are wrong, at least on the DME side.

Thanks Max_VQ for all the help (your attachments have been fantastic!).

I agree that the diagnostic information from the OBDII port seems to change so I ran it a least a half dozen times, resetting each time.

For example, from the OBDII port, after reconnecting the brake pressure sensor connection, I did reset the original error code which, weirdly, initially came back as:
81 Einlassventil : vorne links (inlet valve, front left)
105 Brems Licht Schalter (brake light switch)

But then, after resetting the OBDII error, the ABS test consistently reported:
81 inlet valve, front left
(even after multiple error resets)

To test the output voltage, you could make up something like this: http://www.picoauto.com/breakout-lead.html

Interesting. I generally buy any tool I need. I'm guessing, from the pic below, is it that you shove the leads into the BACK of the brake pressure sensor while the sensor is connected to the hydro unit?

If so, this would be the suggested procedure to test a brake pressure sensor (but now my error is "inlet valve"???).

1. Turn off ignition
2. Remove the three-wire brake pressure sensor electrical connector (do not remove the sensor, just remove the connector!)
3. Check the brake pressure sensor (male prongs) for continuity with a DMM we don't know what values to expect???? but we may as well write them here
4. Turn ignition on (car not running)
5. Test brake pressure connector (female side) for 12v supply voltage
6. Turn ignition off
7. Reconnect brake pressure sensor
... here's where the test jig comes in ...
8. Stick three 1.5mm test probes into the BACK of the connected brake pressure connector in situ
9. Attach your DMM voltmeter to the power & signal wires (we need to determine which color is power, ground, and signal)
10. Turn ignition on (car idling)
11. Ask an assistant to press on the brake pedal as you measure the voltage change
12. You should see 0 volts to 5 volts corresponding to 0 to 250 bar pressure (0 to 3,626 psi) changes in the front brake lines as your assistant presses on the brake pedal from soft to firm.

How does this look for a test sequence for the brake pressure sensor?

The questions for confirmation are:

A) Is the suggestion to stick a probe into the BACK of the brake pressure sensor to measure voltage sweep in situ?

B) Does anyone have an idea what part the diagnostic message "inlet valve, left" is referring to?

Originally Posted by bluebee

Interesting. I generally buy any tool I need. I'm guessing, from the pic below, is it that you shove the leads into the BACK of the brake pressure sensor while the sensor is connected to the hydro unit?

Not quite... The cable is like a "Y" adapter:
(1) one wire (for example the top left of the Y) goes to the pressure sensor
(2) The same coloured wire as (1) goes to the connector that attaches to the sensor. (this is like the top right of the Y)
(3) the "bottom of the Y" goes to your meter. (same colour as 1&2)

This allows you to insert your meter/scope in between the sensor and plug.

YOU MUST BER VERY CAREFUL NOT TO MIX UP THE WIRES. YOU COULD SHORT SOMETHING OUT AND KILL YOUR ABS controller or DME.

You don't have to buy this, as I think it is expensive, but you could make something for much less.

Originally Posted by Max_VQ

The cable is like a "Y" ... you could make something for much less.

Hi Max_VQ,
Oh. I understand. It's a splice. Like in the picture below?

I agree, for DIY use, the professional jig is pretty expensive (for what it is) ... so I think I will scour the local auto parts stores (hardware stores?) for a tiny SQUARE wire to fit into the female end of the brake pressure sensor connector.

Does anyone know where I can get a secure tiny square female connector I can use for the male end?

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..

Originally Posted by 540iman

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.

I do live where they salt the roads. Back probe the connector then. I just think you or bluebee is making this harder than it is. Pierce the wire with a sharp probe or back probe the connector. Either way it is no big deal.

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?