E39 Wheel sensor help please

Hello All

2000 "W" redg E39 528i SE auto

Tonight on the M25 I lost the speedo, and "vacuum" guage, the odometer, and I've the ABS fault light on, & all but temp reading on the OBC.

I guess this is all down to one wheel sensor, anyone any experience of this fault, and/or know which wheel sensor it is ? 

Thanks K

On an internet search I found this :

Hi guys. I posted this write-up in a separate thread, and several people suggested that I replicate it here. Between the time I first posted it (9/06) and now, I've used the procedure yet again to locate a failed speed sensor. For those keeping score, that means I've replaced three of the four sensors on my 540i in the past two years.

The actual sensor replacement is trivial; the tricky part is figuring out which sensor failed. I hope that this can help somebody!

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Replacement of Wheel Speed Sensor
E39 BMW

Synopsis: A malfunctioning wheel speed sensor can cause the anti-lock braking and traction control systems to become disabled, among other things.

Symptoms: Three lights appear simultaneously on the dashboard: ABS, an amber BRAKE, and the triangular "traction lost" icon. Traction control is not operational, nor is antilock braking. One or more of the speedometer, odometer, or cruise control might also be inoperable.

Tools required: Multimeter capable of testing diodes. 5 mm Allen wrench. Long, very narrow probes for multimeter, or equivalent. For rear sensors, a 10 mm socket, 8 mm socket, flat-head screwdriver, and needle-nose pliers might be required to remove trim.

Difficulty: Easy

Diagnosis: A BMW service computer can isolate the source of the problem; standard OBDII code readers cannot pull the requisite information. The Peake Research code reader seems to be capable of reporting whether or not a problem exists, but there do not appear to be any codes that reveal the location of the faulty sensor. If a wheel speed sensor is suspected, and no computer is available, the identification process is one of trial and error. Jack up you car and support appropriately. Access to the sensor is considerably easier with the wheel removed, so pick a corner and remove the wheel.

It is worth noting that certain failure modes are associated with particular corners of the car. If the speedometer and odometer do not work, the driver's side rear sensor is probably bad. If the speedometer works but the cruise control does not, then the passenger side rear senor is probably bad.

Locate the sensor (mounted on the wheel carrier near the hub) and trace its wire back to a blue connector. The connector might be housed in a black plastic box. Open the hinged box if it is present. There might be a second connector next to the blue speed sensor connector; that's for the brake pad wear sensor. Pull the blue speed sensor connector out of the box and disconnect the two sides.

Deep inside the sensor side of the connector, there are two metal prongs. Now comes the tricky part. Turn the mutimeter on and to its diode testing setting (it looks like an arrow with a line in front of it). Connect one probe to one of the prongs, and the other probe to the other prong. The meter should read ~1.4-1.8 V or indicate an "open" condition (e.g., "OL"). Reverse the probes. Once again, the meter should indicate either an open condition or a 1.4-1.8 V drop, but the result should be whichever one you didn't see the first time. If you see any other result, such as 600 mV in each direction or 0.0 V in either direction, you've probably found the bad sensor; congratulations! Note that a 0.0 V drop is possibly indicative of a poor test setup; verify that you are not shorting the multimeter probes. If the sensor tests out okay, try again at a different wheel. Of course, it's always possible that one of your speed sensors has failed in a way that wouldn't present itself in this test. In the worst case, you'd have to go to the dealer anyway for the diagnosis.

You might want to try another wheel even if you think you found the bad sensor in order to confirm that your technique is good. It's sometimes a bit tricky to get a good connection to those prongs. If you think you found two bad sensors, you probably messed up.

Be sure to reconnect all of the sensors that you believe are good. Once you have identified the faulty sensor, obtain a replacement BMW part. One sensor on my 540i was $120; I've read reports of them retailing for as little as $70.

Other possible causes: Reports indicate that the cause of the sensor failure might be a frayed wheel-speed sensor wire in the wheel well; inspect the entire visible run of the cable carefully to confirm the lack of frayed or pinched wires. If frayed wires are found, attempt repair using common wire-repair techniques. Other reports indicate that a bad ABS controller might cause similar symptoms.

Replacement: With the wheel off at the corner with the broken sensor, and the sensor cable disconnected, unsnap the sensor wire from the two mount points on the steering knuckle. Follow the cable to the point where it ends at the sensor. The sensor is attached to the car with one or two small bolts. A 5mm Allen wrench is required to remove the bolts. You might have to do this blind, but it's not that hard. After the bolts are removed, gently pull the sensor straight out of its hole. Put the new sensor where the old one was, and reverse the removal process. There were two bolts holding my old front sensor, but the new front sensor included only one mounting hole. Due to the sensor construction, I don't believe it is a problem to use only one bolt. Be sure to hook the new sensor back to the other connector, and don't forget to snap the cable into the cable brackets.

Commentary: I have had three speed sensors fail on my 1999 540i. The first time, a front sensor failed. The DSC, ABS, and brake warning lights were be off when the car was first started but would turn on after driving a couple hundred feet. A year later, a rear sensor failed. The same three lights shone at startup and never reset. The Peake reader indicated code 0F 78. A few months after that, I had another rear sensor fail. I was able to use the above procedure all three times to successfully locate the failed sensor.

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Jeff
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Edit: Here is a DIY with pics from M5board.com.
http://www.m5board.com/vbulletin/e39...front-diy.html

I've had a look today, as on saturday the bloody thing was working fine, so the diagnostic software my mate has was showing no fault, no codes stored.

I've checked them with a multimeter, and they are rears both 1.622, offside front 1.611, but the nearside front is 2.022, so that one is looking dodgy, and would explain why sometimes it works, and sometimes it doesn't.

The only thing that doesn't tie in with the chaps post, is if I've found the dodgy one, then on my 2000 UK spec car, it's the front nearside that controls the speedometer, odometer, etc etc.

I'll keep you posted, as once I've sorted this, we'll be able to put it in the "how to do" section .............. , as I'm not about to be beaten by a poxy 2 wire inductive sensor.

Once I've replaced one, cured the problem etc, I'll cut the plug of the faulty one and make a small battery powered test rig that can check them, and then post the details on here.

These aren't magic, they are only 2 wire inductive sensors !

Ah, welcome to world of the E39 and faulty wheel sensors.

Sounds like you are well on your way to diagnosing which one it is.

If it is a front one that is faulty then another symptom will be rough autobox gear shifts as the front wheel sensors are used to control the shift points of the autobox.

Uh oh :

http://forums.bimmerforums.com/forum/showthread.php?t=700242

I've repaired a few ovlov ones for people, but from this thread the beemer one looks ........ well ........ sh*te !

And ....... pictures

Andrew

Whilst you are correct in what you say regarding the wiring loom, that kind of issue, on a 10 year old car with full bmwsh is very very unlikely, that kind of issue will show itself quite quickly if a "clip" is missed during build, allowing the loom to rub on something, it can also be an issue if somebody has been playing with a cars loom, fitting audio crap, lights, whatever, or if the car has been involved in a serious bump etc.

None of the above applies to this car.

This issue regarding the faliure of electronic circuits in cars (and many other things to be honest) is a mixture of EU regs (I'll explain in a moment), very complicated circuitry, and extremes of temperature etc in a cars engine bay.

The abs unit has been an issue on Volvo V70 T5's for example, but not in most cases on the other V70's, and this is supposedly down to the abs mounting position versus the exhaust manifold ( I've actually repaired three of these for mates).

The EU regs bit dates from either 1995 or 2005, I can't remember which, and concerns the use of lead in solder, they've made everyone (with a few exceptions) go lead free, due to the amount of polution caused by throwing away electrical/electronic items into landfill, and the lead getting into the soil (it must be an issue, but it bemuses me, as that's where it came from .... the ground, so we're only putting it back).

The exceptions I'm aware of are the aircraft and medical industries, because leaded solder has a very long history,we can predict how it will react, lead free solder doesn't have a history.

There are issues regarding components too, a component built using lead free technology doesn't like being soldered with leaded solder and vice versa, so repairing older circuits with new components can be an issue (reliability wise)

Leaded solder used to be on red reels, and unleaded on green reels, but I have noticed that the buggars are palcing lead free on red reels now, I can still buy leaded solder (for how long we're not sure), but from non trade outlets, you should only be able to get lead free now.

So, my knowledge of the solder issue, and the Volvo issue, combined with the fact the problem isn't a sensor, and given there is so much information on the internet from the states about this (where they have more extremes of temperature than we do), is what is leading me to suspect the abs module.

If I'm wrong, I'll post it.

Nigel wrote: Some more info for you lads ...... mines the 265 223 001 http://www.ecutesting.com/bmw_5_series__e39__abs_pump_mo.htm l I'll get a quote, and let you know how much

£150.00, 2 - 3 working days for a repair, no exchange units in stock

Nigel wrote: Andrew Whilst you are correct in what you say regarding the wiring loom, that kind of issue, on a 10 year old car with full bmwsh is very very unlikely, that kind of issue will show itself quite quickly if a "clip" is missed during build, allowing the loom to rub on something, it can also be an issue if somebody has been playing with a cars loom, fitting audio crap, lights, whatever, or if the car has been involved in a serious bump etc.

I agree but wouldn't an older car be mibbie more susceptable to wiring being chaffed as it has had 10 years worth of road bumps.

All I'm saying is don't discount it as you may be going down a road of forking out more hard earned than you need to!

Have a read of this which happened to an E39 M5 after a few years worth of road bumps

Keep going Nigel, you'll get there.

It's frustrating when a simple fault with part of an electronic system is a complete unit at £x00's of pounds when it only needs a new bit of electronic circuitry at a few pence or a couple of quid at most.

Let us know how you get on.

Righty ho

I've been and had it coded, all seems ok.

I'll write this up properly, with what I've learnt, all the contacts etc, and pop it in the how to do section