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The BMW 5-Series (E39 chassis) was introduced in the United States as a 1997 model year car and lasted until the 2004 when the E60 chassis was released. The United States saw several variations including the 525i, 528i, 530i and 540i. -- View the E39 Wiki

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Old 02-29-2016, 05:48 PM
sactown540 sactown540 is offline
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ABS troubleshooting (trifecta)

Hey everyone,

(2001 525i)
So i have the infamous trifecta (DSC, brake & ABS) for the last few months.

It usually pops on only after driving in city streets (non-highway) for 15-20min..I surmise the engine bay becomes hot enough to trip the ABS module..
It sometimes will go off if i drive on the highway for a period of time then pull over and restart. Again i surmise the engine bay cools down which also cools down the abs module allowing it to work properly again..Also if trifecta was on say Monday afternoon it will be off Tuesday morning.

At first only the lights would pop on. Now when all three lights pop on the speedometer will go to zero, MPG gauge becomes inoperable and the odometer stops. BUT the cruise control still works.
This lead me to believe the left rear (driver side) speed sensor may be intermittently failing. Maybe heat is somehow affecting it since the exhaust pipe/canister is near by.

I cleaned and DMM checked all speed sensors. I believe my DMM is not working because I didnt get any results. I also didnt get any results when using DMM to check ABS module connector (speed sensors). Just constantly showed "OL".

When the trifecta occurs the cruise control is not affected. I tried swapping the rear speed sensors to see if it would affect the speedometer or cruise control. After swapping rear speed sensors, and having the trifecta appear a few times, I have the same results.
When trifecta occurs speedometer still goes to zero and cruise control still works.
This is leading me to believe the abs module is the culprit. Of course I'm not 100% sure since I havent been able to DMM check the speed sensors correctly.

Also when using INPA I get no codes for speed sensor or ABS. Live checking of the speed sensors show they all work fine when trifecta does not occur. When it occurs the left rear speed sensor does not work. I assume the abs module is affecting it since I swapped both rear speed sensors and i doubt both are bad.

Any other ideas? Would you assume its the ABS module from my results and get it repaired?

My plan next is to test my DMM to see if its broken then retest speed sensors themselves and ABS connector.

thanks for any help
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Old 02-29-2016, 06:11 PM
ca2014mp2 ca2014mp2 is offline
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if you replaced the speed sensors... yes, send in the module. you have the classic signs of a faulty abs unit.. ebay fix 85 bucks.. you can drive just fine with out the abs unit... you just are riding old school 1970 style brakes... no abs.. it will be fine for the week it takes to send it off.
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Old 02-29-2016, 06:26 PM
bobdmac bobdmac is offline
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When I recently had the trifecta, and I hooked up my Creator C110, the live data showed all four sensors reading the same speed in mph, which ruled out the sensors as a problem. It turned out that I had forgotten to re-install a fuse in the glove compartment. I think your analysis of a heat-related malfunction is probably accurate. The first time I had it, my symptoms resembled yours, but I didn't have a reader at the time, and so I guessed. It in fact turned out to be the module, which I had successfully rebuilt.
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Old 02-29-2016, 06:32 PM
sactown540 sactown540 is offline
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Originally Posted by bobdmac View Post
When I recently had the trifecta, and I hooked up my Creator C110, the live data showed all four sensors reading the same speed in mph, which ruled out the sensors as a problem. It turned out that I had forgotten to re-install a fuse in the glove compartment. I think your analysis of a heat-related malfunction is probably accurate. The first time I had it, my symptoms resembled yours, but I didn't have a reader at the time, and so I guessed. It in fact turned out to be the module, which I had successfully rebuilt.
I havent checked any fuses..
Did you have cruise control working when trifecta occured?

thanks for your help
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Old 02-29-2016, 06:33 PM
ca2014mp2 ca2014mp2 is offline
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Good point bob also add that you can test with dvom at the connector to the abs module so you don't have to go to each wheel... it's then proves the sensors all the way to the abs unit.. but when you say it gets hot and then stops working or a big bump in the road that screams the unit is bad... If i was in your shoes I would feel confident about sending the unit in..
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Old 02-29-2016, 06:34 PM
sactown540 sactown540 is offline
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Originally Posted by ca2014mp2 View Post
if you replaced the speed sensors... yes, send in the module. you have the classic signs of a faulty abs unit.. ebay fix 85 bucks.. you can drive just fine with out the abs unit... you just are riding old school 1970 style brakes... no abs.. it will be fine for the week it takes to send it off.
I havent replaced speed sensors but need to DMM check them again. I dont want to replace all ($400+ oem)..id rather diagnose them first.
Didnt know i could remove it and still drive the car..thanks for the help
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Old 02-29-2016, 06:38 PM
sactown540 sactown540 is offline
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Originally Posted by ca2014mp2 View Post
Good point bob also add that you can test with dvom at the connector to the abs module so you don't have to go to each wheel... it's then proves the sensors all the way to the abs unit.. but when you say it gets hot and then stops working or a big bump in the road that screams the unit is bad... If i was in your shoes I would feel confident about sending the unit in..
Yeah i tried today to check the abs connector per bluebee post but didnt get any results so i know my dmm is broken or i just dont know what im doing..lol.

Yeah everything is fine in the morning but after driving on the streets for extended period of time the trifecta will pop on..On the highway it usually wont. Seems heat related to me..heat to the abs module or heat to the left rear speed sensor..
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Old 02-29-2016, 06:39 PM
sactown540 sactown540 is offline
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Originally Posted by bobdmac View Post
When I recently had the trifecta, and I hooked up my Creator C110, the live data showed all four sensors reading the same speed in mph, which ruled out the sensors as a problem. It turned out that I had forgotten to re-install a fuse in the glove compartment. I think your analysis of a heat-related malfunction is probably accurate. The first time I had it, my symptoms resembled yours, but I didn't have a reader at the time, and so I guessed. It in fact turned out to be the module, which I had successfully rebuilt.
who did you have rebuild it? how much?
thanks
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Old 02-29-2016, 06:42 PM
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if youre unsure of your meter, put it in ohms mode...touch the red and black probes together. it should read 0 ohms or close. change the mode to dc...touch the leads to the terminals on your car battery. should see close to a 12 volt reading....put it in ac mode...probe one of the electrical outlets around you..should get a reading of 115 volts ac or thereabouts. many dvms have a fuse in them, low amp rating for protection of the unit.it could be blown. if when reading ohms, touching the leads together doesnt show a reading of 0 ohms or close, the probes may be bad. if the probes are removable, disconnect them from the unit and short the connections on the dvm together with a piece of wire of something like that and put it in the ohms mode. if it reads 0, its your probes, if anything else its your meter or the fuse. arent you able to get any codes while the trifecta is lit? no stored codes?
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Old 02-29-2016, 06:45 PM
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Originally Posted by sactown540 View Post
I havent checked any fuses..
Did you have cruise control working when trifecta occured?

thanks for your help
the intermittency kinda rules out a bad fuse.
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Old 02-29-2016, 06:51 PM
sactown540 sactown540 is offline
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Originally Posted by mattmar1 View Post
if youre unsure of your meter, put it in ohms mode...touch the red and black probes together. it should read 0 ohms or close. change the mode to dc...touch the leads to the terminals on your car battery. should see close to a 12 volt reading....put it in ac mode...probe one of the electrical outlets around you..should get a reading of 115 volts ac or thereabouts. many dvms have a fuse in them, low amp rating for protection of the unit.it could be blown. if when reading ohms, touching the leads together doesnt show a reading of 0 ohms or close, the probes may be bad. if the probes are removable, disconnect them from the unit and short the connections on the dvm together with a piece of wire of something like that and put it in the ohms mode. if it reads 0, its your probes, if anything else its your meter or the fuse. arent you able to get any codes while the trifecta is lit? no stored codes?
thanks for the tips of checking the DMM. I will review it again and see if its broken. I did try ohms on the speed sensors and even then it would not read anything. It would jump results when the probes were touched together though...idk.

Using INPA i didnt get any codes. I have a few codes for coil#3 but nothing related to ABS, or speed sensors. All I do get is when trifecta comes on and i hook up my computer to live data it shows left rear wheel speed sensor inoperable. But im not sure if the speed sensor intermittently went out or the abs went out and is affecting the speed sensor.
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Old 02-29-2016, 07:24 PM
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for one, youve got to determine why your left rear wss is showing bad..a working dmm comes in handy, or swap the rear sensors and see if it follows. if you read the trifecta troubleshooting instructions, when reading the sensors with a dvm, at one point you reverse the dvm leads.a consistent OL reading irregardless of lead polarity means either a bad meter, open wiring tween the connector and the wss, or a totally shot wss. not sure what you mean with "it would jump results when touching the probes togather" an OL display means infinite resistance between the leads,or its in voltage mode and the voltage read thru the leads is over the set range of the meter.
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Old 02-29-2016, 07:49 PM
sactown540 sactown540 is offline
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Originally Posted by mattmar1 View Post
for one, youve got to determine why your left rear wss is showing bad..a working dmm comes in handy, or swap the rear sensors and see if it follows. if you read the trifecta troubleshooting instructions, when reading the sensors with a dvm, at one point you reverse the dvm leads.a consistent OL reading irregardless of lead polarity means either a bad meter, open wiring tween the connector and the wss, or a totally shot wss. not sure what you mean with "it would jump results when touching the probes togather" an OL display means infinite resistance between the leads,or its in voltage mode and the voltage read thru the leads is over the set range of the meter.
My bad, i wasnt that clear.
My INPA live data showed the rear left speed sensor not working when trifecta occurs.
When trifecta doesnt occur live data shows left rear working fine. (To my knowledge the rear right sensor is cruise control and rear left is speedometer & odometer)
I swapped both rear speed sensors since my cruise control as not been affected by the trifecta. But after swapping them, i have the same results. I doubt both sensors are bad which further lead me to surmise the abs is malfunctioning and not the sensors.

"it would jump results..." i meant that i would touch the two DMM (digital mulit meter) leads together and the DMM screen showed "OL" then to a random voltage then back to "OL" so i assumed it was working. But now since I performed most of the trifecta troubleshooting instructions and have gotten zero results except "OL" i assume my DMM is broken. I need to fix it or get another then retest. Sorry for the confusion.
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Old 02-29-2016, 10:17 PM
Dukkhuli Dukkhuli is offline
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I did same thing mine when i scan sayd front left sensor i change no suces so i rebuild my abs module at myairgags.com 99$ plus shipping and it was a sucses
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Old 02-29-2016, 10:24 PM
Aussie528iT Aussie528iT is offline
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sactown540
The cruise control on your 2001 525i uses the average of the 2 front wheel speed sensors not the rear sensor.
This is the arrangement with all E39s from 8/1998 with fly by wire throttle. ie: with M54, M52TU and M62TU engines.
That's why the cruise control still works when the speedo doesn't.
When you get the "Trifecta" it means that speed info isn't being sent to the CAN bus modules which are engine ECU, Auto gearbox ECU if you have one, instrument panel and ACS/DSC module. All these modules need speed info for one reason or another.
The problem can be an intermittent failure in a speed sensor, a wiring fault in a speed sensor, or an intermittent fault in the ASC/DSC module - usually heat soak related, just to give a few possibilities.

IIRC the wheel speed sensors are Hall effect devices on later cars post 8/1998 so they need to be tested more like diodes. Electronic nerds need to come in here.

RonR
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Old 02-29-2016, 10:28 PM
sactown540 sactown540 is offline
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Originally Posted by Dukkhuli View Post
I did same thing mine when i scan sayd front left sensor i change no suces so i rebuild my abs module at myairgags.com 99$ plus shipping and it was a sucses
thank you
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Old 02-29-2016, 10:31 PM
sactown540 sactown540 is offline
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Originally Posted by Aussie528iT View Post
sactown540
The cruise control on your 2001 525i uses the average of the 2 front wheel speed sensors not the rear sensor.
This is the arrangement with all E39s from 8/1998 with fly by wire throttle. ie: with M54, M52TU and M62TU engines.
That's why the cruise control still works when the speedo doesn't.
When you get the "Trifecta" it means that speed info isn't being sent to the CAN bus modules which are engine ECU, Auto gearbox ECU if you have one, instrument panel and ACS/DSC module. All these modules need speed info for one reason or another.
The problem can be an intermittent failure in a speed sensor, a wiring fault in a speed sensor, or an intermittent fault in the ASC/DSC module - usually heat soak related, just to give a few possibilities.

IIRC the wheel speed sensors are Hall effect devices on later cars post 8/1998 so they need to be tested more like diodes. Electronic nerds need to come in here.

RonR
99 528iT M52TU RHD Euro spec 5HP19
Very interesting. I thought it was the rear right that affects cruise control.
Well to make sure i need to definitely check my speed sensors again.
Thanks for the input!
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Old 03-01-2016, 08:11 AM
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Quote:
Originally Posted by Aussie528iT View Post
sactown540
The cruise control on your 2001 525i uses the average of the 2 front wheel speed sensors not the rear sensor.
This is the arrangement with all E39s from 8/1998 with fly by wire throttle. ie: with M54, M52TU and M62TU engines.
That's why the cruise control still works when the speedo doesn't.

RonR
99 528iT M52TU RHD Euro spec 5HP19
Ron-I do not understand this post! I have a 2000 528iT, build date 7/99, and a couple of years ago my cruise stopped working. Speedo worked fine. So I replaced the right rear wheel speed sensor after it failed Bluebee's diode test and all other WSS passed. I thought my diode tests and the fact that the cruise controlled stopped working was a double test for the right rear WSS.

As soon as I replaced the RR speed sensor, the cruise started working and has worked perfect ever since. So that proves to me that the RR WSS provides the data to the cruise control.

This failure was not intermittent, it was absolutely constant with the engine cold, hot, whatever.

sactown540-I just want to say that you have the classic symptoms of a failed module that needs to be repaired. Your cruise works because the circuits in the module that have to do with the RR sensor are OK, hot or cold engine. All your testing of WSS make no difference unless you are testing them at the wheel connectors. You have no idea if the circuits in the module are working or not as the ABS system works intermittently.

Edit-link to Bluebee's exhaustive ABS posts-
https://www.bimmerfest.com/forums/sh...01#post4205801
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Old 03-01-2016, 08:29 AM
bobdmac bobdmac is offline
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Quote:
Originally Posted by sactown540 View Post
I havent checked any fuses..
Did you have cruise control working when trifecta occured?

thanks for your help
I never tried the cruise control. In fact, I haven't used it since I've had the car.
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Old 03-01-2016, 08:45 AM
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Quote:
Originally Posted by Aussie528iT View Post
sactown540
The cruise control on your 2001 525i uses the average of the 2 front wheel speed sensors not the rear sensor.
This is the arrangement with all E39s from 8/1998 with fly by wire throttle. ie: with M54, M52TU and M62TU engines.
That's why the cruise control still works when the speedo doesn't.
When you get the "Trifecta" it means that speed info isn't being sent to the CAN bus modules which are engine ECU, Auto gearbox ECU if you have one, instrument panel and ACS/DSC module. All these modules need speed info for one reason or another.
The problem can be an intermittent failure in a speed sensor, a wiring fault in a speed sensor, or an intermittent fault in the ASC/DSC module - usually heat soak related, just to give a few possibilities.

IIRC the wheel speed sensors are Hall effect devices on later cars post 8/1998 so they need to be tested more like diodes. Electronic nerds need to come in here.

RonR
99 528iT M52TU RHD Euro spec 5HP19
johnstern was 100% correct, the rr wss is cruise control, the lr speedo. the 99 and 00 model years arent true "fly by wire" throttles, they are cable operated, the dme can override the throttle plate opening (drivers wish) via asc and other problems. and yes the wss's are hall effect and need to be looked at as diode like when testing the dvm way, as is spelled out well in the trifecta troubleshooting threads on here.
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Old 03-01-2016, 08:55 AM
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Originally Posted by sactown540 View Post
My bad, i wasnt that clear.
My INPA live data showed the rear left speed sensor not working when trifecta occurs.
When trifecta doesnt occur live data shows left rear working fine. (To my knowledge the rear right sensor is cruise control and rear left is speedometer & odometer)
I swapped both rear speed sensors since my cruise control as not been affected by the trifecta. But after swapping them, i have the same results. I doubt both sensors are bad which further lead me to surmise the abs is malfunctioning and not the sensors.

"it would jump results..." i meant that i would touch the two DMM (digital mulit meter) leads together and the DMM screen showed "OL" then to a random voltage then back to "OL" so i assumed it was working. But now since I performed most of the trifecta troubleshooting instructions and have gotten zero results except "OL" i assume my DMM is broken. I need to fix it or get another then retest. Sorry for the confusion.
your dvm is definitely suspect, or its leads. in what mode was the dvm set when you touched the leads together and got the jumping reading? if it was ohms, as i suspect it was,it sounds like something is intermittent, probably the leads. the OL meant the leads werent in contact with each other, or whatever was being read had a very high resistance, the "voltage" you read was the resistance, but when it went back to OL with the leads shorted, something aint right here. new dvms are cheap enough, or expensive enough if you want to go that way. however the expensive type is not necessary for what youre doing, a $10 one will accomplish what you want to do.
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Old 03-01-2016, 09:06 AM
bobdmac bobdmac is offline
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A code reader that can display live wheel speed readouts in mph gives you a diagnosis independent of whether the ABS module can read it or not, and you don't have to crawl under the car to mess around with positioning the meter's probes correctly. You just plug it in, choose the menu under "chassis," and get the car rolling. It may be a little more difficult with the extra cord for the engine compartment OBD port, however.
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Old 03-01-2016, 10:36 AM
sactown540 sactown540 is offline
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Originally Posted by johnstern View Post
sactown540-I just want to say that you have the classic symptoms of a failed module that needs to be repaired. Your cruise works because the circuits in the module that have to do with the RR sensor are OK, hot or cold engine. All your testing of WSS make no difference unless you are testing them at the wheel connectors. You have no idea if the circuits in the module are working or not as the ABS system works intermittently.

Edit-link to Bluebee's exhaustive ABS posts-
https://www.bimmerfest.com/forums/sh...01#post4205801
thanks for your input.
I rechecked my INPA codes and realized that the code 30 i get wasnt coil#3 but Left rear sensor. See image attached. I still think its the module since i swapped rear WSS but i will diode test the connector to make sure.
I am a little lost about speed sensor test. I read bluebees post and others several times but im not 100% sure. I must be slow.

Questions:
Can i test sensors outside of car like attached pics? or do they need to be installed?
Do i need to rotate the wheel while testing? I assume no.
Does my setup look right in 3rd pic? Fyi the sensor is out of the wheel hub.

What i did was test the female end of the actual speed sensor (while the sensor was installed into wheel hub and also outside) by probing two prongs within blue connector, but all i get is 'OL'. If im doing the test correctly i assume my DMM is malfunctioning . See 2nd and 3rd attached pics.
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Old 03-02-2016, 12:37 AM
Aussie528iT Aussie528iT is offline
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For those that don't think the cruise control is supplied from the average of the 2 front wheel speed sensors go to the bottom of page 42 of this pdf.
http://www.beisansystems.com/misc/SE...ROL_SYSTEM.pdf

As I said in my post the modules on the CAN bus need speed info that comes from the rear wheel speed sensor.
If this speed info is not there then the CAN bus modules can't work properly and this may prevent the cruise control from working but it is not because the cruise control wheel speed info comes from a rear wheel speed sensor.
Its because the CAN bus modules are missing other speed info that comes from the rear wheel speed sensor.

The M52TU engines are fly by wire. The throttle cable is just a sort of belt and braces approach to provide back up for failure of the potentiometers at the throttle
Instead of the pedal position sensor being at the pedal as in the later M54 engine it is part of the throttle body and is activated by the throttle cable acting at the throttle body.
The throttle body info is on page 51 of the above pdf.

I hope this helps.
RonR
6/99 M52TU 528iT

Last edited by Aussie528iT; 03-02-2016 at 12:45 AM.
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