2000 540i BRAKE, ABS, and DSC lights on, HELP!!!

Again, more stuff with this car.

Here's what happened today.

After having the vavle covers replaced and seeing all the sludge I got, I thought about cutting my losses on this car and trade it in or selling it. I stopped off at CarMax. Ya, I know, what was I thinking. They gave us a good price on a car a few years ago and I have been happy with the Jeep my wife bought from them as well, so I thought I would give them another try. We got a price for the car (what a joke) and went to get something to eat. We get home after they had closed, I parked the car in the drive way, turned it off, went out later to put it in the garage and when I started it the BRAKE, ABS, and DSC light came on. I took it out for a drive and the speedometer and odometer do not work. Could these guys at carmax screwed up something when they inspected it or is it just a coincidence?

Also, I found Bluebee's DIY on this. Great post. Anyway how do I test the 4 wheel sensor circuits from the ABS module connector? Could my problem be the ABS module?

Sorry still new and learning as I go. Any advice would be great.

Originally Posted by LoganWolf

I took it out for a drive and the speedometer and odometer do not work.

The left rear wheel speed sensor is responsible for the speedometer/odometer.

What was the price they gave you? They couldnt have messed anything up, mine did the same thing out of nowhere. Sensors usually go before the module.

Definitely use Bluebee's DIY to check the sensors at the connector. The check is very simple and quick. I would not just start replacing any parts without checking it first.

If you decide to keep the car you should consider changing the engine oil and filter more often and use a good quality synthetic oil. Personally, I would stay away from the engine cleaners that claim to remove sludge if you're considering that method...sometimes that can do more harm than good. The sludge probably occurred due to the PO not maintaining it properly. Sludge, while certainly not a good thing, does not necessarily mean a catastrophic failure is in your future. I'm assuming you are not using coolant and have no oil pressure warnings?

Good luck and I'm sure you can get some sound advise/help in here if if you can't get the issue sorted out.

Originally Posted by Vin M

The left rear wheel speed sensor is responsible for the speedometer/odometer.

And if it's not the sensor it could be the ABS module under the hood.
Module Master fixes them for $300.

I just saw the pics of your engine sludge from one of your previous posts....that's a bunch of sludge.

I still would not use any of the "sludge cleaners" if it were mine. Too great a possibility of sludge chunks clogging the oil pump pick-up that will cause an engine failure. If you are not having any problems, i.e. warning lights, smoking, using coolant, etc., I would use a good synthetic oil and change it along with the filter at reduced change intervals. Sludge typically forms in the "cooler" parts of an engine. If I'm not mistaken, the oil pan can be easily removed on an 8? Remove it and take a look.

Originally Posted by LoganWolf

Could my problem be the ABS module?

The trifecta happens to almost all of us at some point.

In most cases, either a (single) wheel speed sensor is bad or a badly tack-welded steel (power?) wire lifted off its gold bondpad inside the ABS control module.

In all cases, as explained in the DIY you referenced, the first step is a ten-minute test of the four wheel speed sensors with a digital multimeter (DMM).

If the wheel speed sensors are known to be good, then almost everyone simply has it rebuilt by BBA/MM/ATE. Cost is from $150 (which is what I paid, including $25 shipping) to $300 (depends on whom you choose to rebuild it).

Originally Posted by LoganWolf

I found Bluebee's DIY on this. Great post. Anyway how do I test the 4 wheel sensor circuits from the ABS module connector?

I see you did some homework so I'm saddened by that statement because the post you refer to (i.e., post #48) explains exactly how to test the wheel sensors.

Pray tell (so we improve it) - what is missing from the description below?

UNDERSTAND DIGITAL MULTIMETER (DMM) TEST BASICS:
- http://www.allaboutcircuits.com/vol_3/chpt_3/2.html

REMOVE ABS-MODULE CONNECTOR:
- Facing the engine, slide the plastic retaining clip to the right with a 1/4 inch flathead screwdriver.
- It is a plastic retaining clip, so do be careful not to break it; it slides over about 1 1/4 inches or so.
- Once the clip is fully to the right, lift the electrical connector up
- Notice the female (blue) connector with 42 holes (and very tiny lettering)
- DO NOT STICK YOUR TEST LEAD INTO THE SQUARE HOLES!
(Only put test leads into the larger rectangular holes next to the square holes.)


NOTE ABS-MODULE PINOUT: (notice the test lead holes)
- Each wheel sensor circuit has a set of two wires in the ABS connector (pinout kindly supplied by 540iman)
- ABS-connector pins 13,29 = Left rear wheel sensor (also affects speedometer & odometer & tripmeter)
- ABS-connector pins 30,31 = Right rear wheel sensor (also affects cruise control)
- ABS-connector pins 28,12 = Left front wheel sensor (some say it also acts as a steering angle sensor)
- ABS-connector pins 15,16 = Right front wheel sensor (tells gearbox electronics how fast you're going)
Note: These pinouts are in the same order of the diode action of each sensor (do not reverse these numbers)
Note: Don't confuse with the brake pad wear sensor, which is only located on the front left & rear right wheel & which uses a black connector.
Note: ASC cars have only two sensors, one on the front right and the other on the rear left wheel.

UNDERSTAND WHEEL SPEED SENSORS:
Note: The wheel speed sensors are two-wire hall effect transducers which send a digital square wave signal with a low of .75 volts and a high of 2.5 volts to the DSC control unit. Each sensor receives a well-regulated 8 volt power supply from the control module through one wire. The ground path for the sensor is through the second wire back to the control module. The signal is generated by a pulse wheel affecting the voltage flow through the hall element in the sensor. The pulse wheel is integrated into the wheel bearing assembly, behind the seal. This protects the trigger wheel from foreign substances which may affect the wheel speed signal.

TEST WHEEL SENSOR CIRCUIT FROM THE ABS CONNECTOR (also checks wiring circuit):
OPTIONAL: Jack car up (so that all four wheels can be spun to test voltage & resistance fluctuations of the hall-effect sensors)
- Turn the car off and remove the key from the ignition.
- TEST 1: Switch the DMM into the diode test position
- Wrap a stiff 20AWG wire onto the ends of your DMM probe for sticking into ABS-connector pins
- Label the positive 20AWG wire with white tape so that you won't get confused as you switch back and forth
- Stick the ends of the wire into the appropriate female holes of the ABS connector (13-29, 30-31, 28-12, 15-16)
- In one direction, you should see 1.7 to 1.8 volts (note the pinouts mentioned are in order, positive to negative)
- In the other direction, you should see OL or some other infinite reading (open circuit)
- TEST 2: Switch the DMM into resistance checking mode (optional)
- You should see around 3.3 Mega ohms in one direction & approximately twice that in the other direction (but some say more)
- TEST 3: If desired spin the wheel at about 1 revolution per second, by hand (the resistance should fluctuate as the wheel spins)
- TEST 4: Switch the DMM into millivolt mode (optional) & again spin the tire & wheel assembly by hand (test-lead polarity won't matter)
- You should read between 1 and 5 mV when you spin the hub (no voltage implicate the sensor or circuit)
- OPTIONAL TESTS BELOW REQUIRE FLYING LEADS WITH THE IGNITION SYSTEM ABS SYSTEM CONNECTED & POWERED UP:
- TEST 5: Swith the DMM into the 10v and attach flying leads to the sensors with the power on
- You should see the voltage going to the sensor and the return signal
- Expect a baseline voltage of about +5 to +12 volts depending on the ABS system (does anyone know this value?)
- Expect that baseline voltage to the sensor to change (by how much?) as you spin the wheels
- TEST 6: Hook an oscilloscope with "flying leads" to the ABS sensors (notice that the ABS system must be powered)
- You should see nice clean square waves generated as you hand spin the wheels at about 1 revolution per second.
Note: The oscilliscope can detect problems that can't easily be found with a DMM (A scope pattern for a wheel speed sensor should show a classic sine wave alternating current pattern that changes both in frequency and amplitude with wheel speed. As the wheel is turned faster, signal frequency and amplitude should both increase. Damaged or missing teeth on the sensor ring will show up as flat spots or gaps in the sine wave pattern. A bent axle or hub will produce an undulating pattern that changes as the strength of the sensor signal changes with every revolution. If the scope pattern produced by the sensor is flattened (diminished amplitude) or is erratic, it usually indicates a weak signal caused by an excessively wide air gap between the tip of the sensor and its ring, or a buildup of metallic debris on the end of the sensor. A weak signal can also be caused by internal resistance in the sensor or its wiring circuit, or loose or corroded wiring connectors.)


INTERPRET DIODE-TEST RESULTS:
- If the DMM, in diode mode, reads infinity ("OL") in both directions, you've got a bad sensor or circuit
- If the DMM, in resistance mode, reads much greater than 7Mohms, you've got a bad sensor or circuit
- If all 4 sensors read OK, it's most likely the ABS control unit.
- If you think you found two bad sensors, you probably messed up.
- Rarely is the cause due to bad steering angle (yaw/lew) sensors
- Rarely is the cause due to a bad hydro unit
- The problem is almost always a wheel rotation sensor or the ABS control unit

ACTUAL RESULTS ON MY 2002 E39 THIS MEMORIAL DAY WEEKEND:


DOUBLECHECK WHEEL SENSORS AT THE WHEEL:
Note: You can run this test w/o removing the wheel but access to the sensor connector is easier with the wheels off the E39
- If one or more sensor circuits test bad in any of the three tests above ... then ...
- Locate the sensor blue connector in the rear of each front wheel well by turning the front wheels
- Easiest to first locate the sensor (bolted on the wheel carrier near the hub) and trace its wire back to a black plastic hinged box housing
- Open the locked hinged plastic rectangular black box with a small flathead screwdriver
- Locate the blue wheel sensor connector (next to a black brake wear sensor connector)
- Pull the blue wheel sensor connector out of the box and disconnect the two sides
- Re-check the sensor there with the diode function of the DMM



CHECK WHEEL SENSORS OFF THE VEHICLE:
- If any sensor still checks bad, pull the sensor off the vehicle for a closer inspection
- Chock wheels and jack E39 BMW and jack stand at the 4 jack pad locations
- Remove 4mm allen head bolts to sensor retention screw (two retaining bolts for fronts, 1 bolt for the rears)
- Pull wheel sensor out of hub assembly, straight up.
- Clean with CRC electronic cleaner
- Check with DMM diode-test meter as before
- Grease with Staburags NBU 12/K or equivalent grease
- Replace sensor back into hub assembly, snug tighten to 6 foot pounds
- Replace rear wheel, tighten to 82 to 96 foot pounds
Note: You might wish to swap sensors on the same axle when replacing so as to obtain further diagnostic information should an anomaly occur.
Note: Here is a picture of a dirty and cleaned sensor (magnetic particle buildup)

You know I had the same thing (the three lights on + speedometer not working) happen to my wife's 2000 540 after I had it up to replace the water pump. In Bluebee's DYI which is linked in her post here among the first things to try is slowly turn the steering wheel from far left to right. I assume this will reset the steering angle sensor and since I did rotate the steering wheel while the car was up with engine off to get an easier access for the jack I thought I might have done something to throw off the sensor and I'd give it a try. Unbelievably it has been several weeks since and she has not had the lights come on again. I am still not completely convinced that this was the fix as my reasoning tells me that things seldom get repaired by just turning the steering wheel but this will be the easiest thing to try. They might have turned the wheel with the car up as I did. Again, it might just be my imagination just trying to help.

Thanks for the replies. I stopped by local Autozone and had them check for error codes on the OBD but no code errors showed up. I'm going to pick up a new DMM tomorrow. The one I have is about 15 years old and it is a little out of date. Besides I don't think I have used since I purchased it and I really don't trust it.

I hope I can follow Bluebees write up and found out what is going on.

http://www.eaceuroparts.com/catalog/product/426

When you determine your module is bad give me a call.

I need of some more guidance on testing the ABS module connector . First off I grabbed the wrong wire at Lowes. Picked some regular galvanized 20 AWG not electrical, go figure. I know it will carry a current so I tried it anyway. With the meter set to diode pins 13,19 gave a reading that would fluctuate all others stayed at 1. Any idea what's bad?

The car got mad that you went to get a # on selling it!
All my cars had some weird failures as soon as i put up a "for sale" sign or listed them online for sale. lol scary.

Pin 19 is feeding the engine control module and Pin 13 feeds the sensor. I think with the "1" readings, you're not making a connection with the test ports.....try a "jumbo" paper clip....worked well for me.

The best advice ANYONE can give you is to learn how to use the search function. How many times are we going to have to go over this...

Originally Posted by LoganWolf

Any idea what's bad?

It's really hard for us to 'guess' (especially since I didn't experience major problems reading so I never learned the troubleshooting steps); but, taking a long shot stab at it ...

• Maybe you put the wire in the wrong hole (there are two holes for every pin)?
• Maybe the wire is still too thick (see my note below about 20 AWG)
• Try this test trick from Fleetman himself over in post #398 of the ABS thread:

Originally Posted by Fleetman

check that you are making a connection at the ABS connector (meaning your "test" leads are ok to use) is to probe for 12vdc at ports, 2, 3, 6 or 7 (switch your DMM to DCv) along with a good, known ground....

As for the 20 AWG, it was a long time ago (about a year), but, IIRC, I found the wires to use as probes lying around so I wasn't certain what AWG they were. So I measured them with my micrometer, and then looked up in the AWG wire tables to surmise they were 20 AWG.

Thinking back on that, I may not have been right (I don't really know at this point). Actually, I 'still' have the wires so I could measure them again.

Anyway, we should ask anyone 'else' who tested this successfully what AWG they used to be sure of that 20 AWG that I quoted loooong ago (in post #48 of this thread).

Couple of things...........

1. The new DMM I bought was bad. Took it back and exchanged it for a different one, also bad. Got a third one and guess what, third time is a charm.
2. Used paper clips instead of wire.
3. ABS-connector pins 13,29 read 500-600mV. Left rear wheel sensor bad. That's my guess. Going to replace it tomorrow. Found it locally for $72.

Will let you know how it worked out.

Originally Posted by 540iman

The best advice ANYONE can give you is to learn how to use the search function. How many times are we going to have to go over this...

I think I figured out how to use it, I'm just green. 1st BMW. I haved owned 7 fords, 1 Mits., and a Jeep, all I ever needed to do was the basics (breaks, oil, shocks, alternator, etc.) All had over 100,000 before I got rid of them and they were still running great. This BMW has been a challange, so I'm still learning........

Running a cheap transmission Fluid in your engine is a good, gentle sludge cleaner. i would run about a quart of ATF for about 30 min before changing my oil. ATF is rich in detergents, but like Fleetman said, the concetrated engine flush fluids may do all too good of a job, and remove large chunks of sludge debris and let them clogg oil gallies and plug the pump pickup screen.

you go Loganwolf! It sounds as if you've probably found your problem and the speed sensor will probably take care of it.

As for the sludge, as long as you're not having a problem with warning lights, smoking and etc., I would simply keep changing the oil and filter regularly....in my experiences, sludge forms in the cooler spots in the engine and doesn't necessarily migrate to other areas UNLESS you use a cleaner.

Yes, a BMW can be a challenge but there's nothing on our cars that cannot be repaired by using the assistance of others in here. I've gotten frustrated with the "search" myself at times (soooo much reading) but it always gives me an answer. Use the search when possible and if you still haven't found your answer or need a clarification.....ask away young grasshopper!

Originally Posted by BillAngel

Running a cheap transmission Fluid in your engine is a good, gentle sludge cleaner. i would run about a quart of ATF for about 30 min before changing my oil. ATF is rich in detergents, but like Fleetman said, the concetrated engine flush fluids may do all too good of a job, and remove large chunks of sludge debris and let them clogg oil gallies and plug the pump pickup screen.

I put some Seafoam in there a few days ago, about 1/4 of a bottle. Car still smokes a ton if not more and it has burned about a quart of oil. I've been looking at other BMW's at some of the small lots around town (6 total) and all of the ones I have looked at have as much sludge if not more. One had green slime in it and so much slugde that it had frozen the oil cap (sales guy used pliers to break it loose ). I'm guessing it was a mixture of water, oil and coolant.

I plan on changing the oil in about 500 miles. Then again at a 1000 without Seafoam and see what I got. I did check the oil filter for debris and so far just some small stuff, no big chuncks.

SeaFoam intake cleaner or oil treatment (do they make an oil treatment).
If it is Seafoam that you induce into your motor via a vacuum line, then it is not doing anything but cleaning out your intake manifold and the tops of the intake valves.

Just got done looking at the sensors. Oh what fun.....

Here is what I found.

When I purchased the car, the previous owner had the breaks and rotors done for me. This was quite generous I thought until I took a good look at things. Some how the sensors on all four tires are hanging down loose just a little bit. They are close to the rotors. They all look burnt to a crisp. I called the previous owner and he sent me to a break shop (pre-paid). They looked it over. He then showed me what was wrong and how the guy who did the breaks did not use what looked like a heavy coat hanger cut in half to hold the sensor in place when the pads and rotors where put back on. This guy had two other cars in his shop with the same problem, a Lexus and another BMW. He gave me a reasonable quote of $450(about $100 for each sensor and $75 for labor). He called the previous owner and told him the price. He thought it over and after seeing the pictures of the sludge, which he says he was unaware of, he decided apologetically to just give me my money back on the car or fix the sensors.

Somehow I feel lucky but I'm not sure how. Great guy and I love the car, I also have grown attached to it but the sludge is so bad. He gave me a few days to decide. So I have an appointment for Friday to have the sensors fixed or to take the car back to him.

Wait. So you just bought this car and were going to trade it in? I would get your money back and find a 5 you are more comfortable with.

Originally Posted by LoganWolf

He then showed me what was wrong and how the guy who did the breaks did not use what looked like a heavy coat hanger cut in half to hold the sensor in place when the pads and rotors where put back on.

I'm glad you are working it out with the previous owner but I have two comments based only on what you've said (it would be nice to see a picture of what you've described).

The first comment is that I'm incredulous that a 'mechanic' (a) had to even remove the sensors (as they're generally not removed during a brake job) and (b) that they could possibly put them back with a coat hanger. One set of sensors has a single bolt holding it in (how hard could 'that' be to replace?), while the other axle has two bolts on each sensor. It's not a difficult job by any means to bolt back in (it might be difficult to remove, but that's what mechanics do every day).

My second comment, I hesitate to say, well ... because I don't wish to offend ... and, I generally let a few typos slip ... but ... ummm ... you wrote it multiple times ... so ... ummm, I'll whisper this gently ... it's brake, not break.

Back on topic ... please post a picture of the coat-hanger sensors as I've never seen a brake job done that way so I, for one, am intrigued by what is there.

I would get the money back, Check out craigslist.com, there are always BMW 5 series for sale. Find one you may like, take to your mechanic, have him do a thorough inspection.