E32 ABS sensor testing procedure

[shogun]

pertains to a E32 , build year. 08/1988 ,730i
(could also work for other models)


The sensors are quite easy to test with a simple ohm meter, Remove the cover from the motronic enclosure (4 screws), situated on the passenger side (left hand drive car) in front of the windshield. The ABS mudule is closest to the cooling fan, The brown relay between the modules is the ABS relay. Unlock the plug from the ABS module and pull it off

You cannot measure to ground because both conductors, center and shield, run directly to the connector on the ABS controller and are connected to ground through the controller. If you pull the connector, you disconnect the ground.

This is how one does it:

Pull the connector off the ABS module and turn it upside down. You will see 2 rows of pins, a short row and a somewhat longer row. The shorter row contains the odd numbered pins, the longer row contains the even numbered pins. The counting starts from the side opposite the cable entry, so from the fender.

now measure simply on the following pins:

Pin 4 and 6 = sensor left front 1000 ohm (red center)
pin 9 and 7 = sensor left rear 1000 ohm (white center)
pin 21 and 11 = Sensor right front 1000 ohm (yellow center)
pin 26 and 24 = sensor right rear 1000 ohm (green center)

where 4, 9, 21 , 26 are the shields=ground. transparent insulation.

one can open the plug easy by loosening the 3 screws. One can check if the colors are correct and see the numbers on the pins.

The resistance values can vary between 600 and 1600 ohm. Values below mean there is a short in the cable or sensor. The sensors have a 2 pin connector to feed through the frame. One in each front wheel well. The rear ones are probably under the rear seat.

You can measure directly on the plug but measuring on the ABS module is probably easier.

Most likely the cables in the wheel wells are broken because of the constant movements.

here you will have to remove the sensor and measure.

[shogun]

More info and hints on ABS faults from BBA Reman, advanced hints and tips bmw abs problems
http://www.bba-reman.com/content.asp...w_abs_problems

[kibokojoe]

Shogun
I am trying to find a ABS problem on my sons 91 735i e32. His ABS module only has 12 pins not 26 as you have mentioned. I have checked the ohms (meter set on 2K) on all of the sensors at the first connector and I get ~1.00 except the front right sensor which is 0.95. I don't think this is the problem. I would like to check the wire all the way up to the ABS unit but don't know which wires to try. Can you help me out


Thanks
Ken

[shogun]

There an electric guru has to chime in, I can only give you a link to the ETM http://shark.armchair.mb.ca/~dave/BMW/e32/

I have only found this info
https://www.bmwtechinfo.com/repair/m...ges/941604.jpg
from E36, unfortunately the pics do not work anymore http://www.bimmerboard.com/forums/posts/1071676

here is an ABS pinout with 35 pins (not all connected) , scroll down: ABS Steuergerät Anschlüsse E32 aus BMWs Elektronikwerkstatthandbuch: http://www.750i.de/d/repair.htm

here copied and translated by me:

Pin #.... Richtung..........Funktion..............Position
1............ E................ Battery............. ABS relais
2............ A....... Switched ground.... Magnet valve front left
4............ E.............. Ground.............. Wheel sensor
6............ E.... Wheel sensor front left.........----------
7............ E..... Wheel sensor rear left.........----------
9............ E............. Ground........... Wheel sensor rear left
10...........E..... Ground distribution..............----------
11.......... E..... Wheel sensor front right.......-----------------
14.......... E....... pump relais input..............------------------
15.......... E........... battery power................. generator
18.......... E......... switched ground....... magnet valve rear left
19.......... E......... switched ground....... magnet valve rear right
20.......... E....... Ground distribution.......-----------------------
21.......... E................ ground............ wheel sensor front right
24...........E.... wheel sensor rear right.....------------------------
25.......... E......... brake light switch........------------------------
26.......... E........... ground.................. wheel sensor rear right
27.......... A......... switched ground.................. valve relais
28.......... A........... switched ground................ pump relais
29.......... A........... display ground........... check control display
32.......... E......... display valve relais(?)............ valve relais
34.......... E............. ground distribution.............----------------
35.......... A............... switched ground......... magnet valve front right

Hinweis/notes:
E ist Eingang (zum Steuergerät), A ist Ausgang (vom Steuergerät) = E = input and A output to/from control module
Anschlüsse, die nicht erwähnt wurden, sind nicht angeschlossen. Connectors not mentioned are not connected

Widerstandswerte/resistance value:
Radsensoren/wheel sensors < 1 Ohm
Ventilrelais/valve relays 70..100 Ohm
Motorrelais/motor relays 34..58 Ohm

[whiskychaser]

On the old type wheel speed sensors there is another test you might try. Put your meter on AC range instead of ohms and spin the wheel. You should get a reading of a couple of hundred mV. If you find a break in the wiring after looking at the diagrams Shogun posted, check the leads where they come out of the bodywork down to the sensor plug. I worked on an E60 recently and that had just such a problem - the wire had chafed on the bodywork. I have DIS so could identify the area of the fault pretty quickly, particularly as it shows the road speed of each wheel. But it created 8 faults in 4 modules, cruise control didn't work and the cluster was lit like a Christmas tree. So much for progress

[stacksandkate]

I've done both the tests suggested here and all seems okay with the sensors and the wiring. I discovered the previous owner had taken the globe out of the ABS warning light as it remains on all the time. Any other suggestions? How about that relay beside the ABS module? can that be tested? Also my connector had the pins in number order with the shorter row 1-11 (I think) and the longer row 11-whatever the last number is. Figured it out though once I took the cover off the plug. Thanks for the tips. My car is a 1988 E32 735i

[whiskychaser]

There is only so much you can do with a meter. I'm actually troubleshooting a problem on my E46 and considered the fact that while the sensors may ohm out ok, they may be providing false readings. Reading fault code memories is useful but this is where live data comes in to its own. This is a screenshot I took yesterday. You can see that all the wheel speed sensors are well within 2kmph of each other and the brake is applied. You wont have the bottom three sensors on your car so the fault will be much easier to find

[biasvoltage]

I'm trying to delve into the dark arts of INPA, I just received my 20 pin ADS interface cable from Ebay but I can't find the software anywhere. Seems like everywhere I can find to download it is a trojan horse/spambot/fake/otherwise untrustworthy site that makes my virus protection light up like a Christmas tree.

[whiskychaser]

I'm trying to delve into the dark arts of INPA, I just received my 20 pin ADS interface cable from Ebay but I can't find the software anywhere. Seems like everywhere I can find to download it is a trojan horse/spambot/fake/otherwise untrustworthy site that makes my virus protection light up like a Christmas tree.

Check out the diagnostic software forum

[pandaboo911]

I've done both the tests suggested here and all seems okay with the sensors and the wiring. I discovered the previous owner had taken the globe out of the ABS warning light as it remains on all the time. Any other suggestions? How about that relay beside the ABS module? can that be tested? Also my connector had the pins in number order with the shorter row 1-11 (I think) and the longer row 11-whatever the last number is. Figured it out though once I took the cover off the plug. Thanks for the tips. My car is a 1988 E32 735i

Same problem here. I have an 88 735 as well. Abs light on constantly, but all the sensors are good. Not sure where the abs relay is located, but my abs computer doesn't seem to be getting any power.

Lmk of you ever figure it out.

[unity]

Apparently the 750 E32 is different. I could not find anything even close to what is described here. Want to test the sensors as close to the ABS module as possible. Already cleaned the sensors. Maybe I need to clean the gear teeth for the sensors. But want to be sure the sensors are good. ABS/ASC light kicks on after moving just a few feet.

[shogun]

today we could fix a "ABS light on" prob on an E32 750iL of a friend. I already had prepared for the worst case a Bosch hydraulic unit 0265201022 BMW 1157874, fits:1988-1995 E34 Sedan: 518i 520i 524td 525i 530i 535i 540i M5 3.6 3.8, E34 Touring: 530i M5, 1987-1994 E32 730i/L, 735i/L, 740i/L 750i/L/S, 1989-1994 E31 850Ci M70 Automatic, Ref-nr: 0265201022, 0 265 201 022, 34511157874, 1157874, 1 157 874

ABS light was always on, tested the sensors, all o.k. and in line with the details in post 1. Then changed the control unit, did not help. Changed the cluster, just in case there would be something wrong, no change.
Tried the blink test based on the info I translated years ago from a German forum and it said no fault, but the light still on:
ABS/ASC blink test - Only possible on newer E32 (was not specified then in the original post month/year)
German version:
ABS/ASC-Blink-Code
- Bremspedal und Schalter "ASC" gleichzeitig druecken
- Zuendung "an"
- Bremspedal und Schalter loslassen
- ASC-LEUCHTE faengt an zu blinken
BC = BlinkCode

BC 1 = kein Fehler
BC 2 = EMS Fehler
BC 3 = Motronic Fehler (DME/ EMU)
BC 4 = Drehzahlgeber Fehler hinten links
BC 5 = Drehzahlgeber Fehler hinten rechts
BC 6 = Drehzahlgeber Fehler vorne rechts
BC 7 = Drehzahlgeber Fehler vorne links
BC 8 = ABS-Magnetventil hinten links
BC 9 = ABS-Magnetventil hinten rechts
BC10 = ABS-Magnetventil vorne rechts
BC11 = ABS-Magnetventil vorne links
BC12 = ASR-Plungenventil Fehler hinten links
BC13 = ASR-Plungenventil Fehler hinten rechts
BC14 = Ventilrelais Fehler
BC15 = Rueckforderpumpen Fehler
BC16 = Speicherladeventil Fehler
BC17 = Langzeitfehler Druckueberwachung
BC18 = Leckage Fehler (wird auch angezeigt wenn Druckspeicher (Gaspatrone) im ASC+T Hydraulikblock schadhaft ist (z. B. leer)
BC19 = Druck Fehler
BC20 = Getriebebeinflussung Leitungsfehler
BC21 = ABS/ASR-Regelgeraete Fehler
BC22 = TD-Signal Fehler (duerfte/koennte Tachoimpuls sein)
BC23 = Option pin Leitungs Fehler

Zu BC 22:
TD Signal Fehler
Regelgeraet Kl. 55
Zuendung aus
Stecker vom ABS/ASR-Regelgeraet und Motronic-Steuergeraet Bank links abziehen
Leitung vom ABS/ASR-Regelgeraet Kl.55 zum Motronic- Steuergeraet Kl.6 auf Unterbrechung/Plus-/und Masseschluss pruefen.
wenn in Ordnung
Fehlerspeicher Motronic auslesen
wenn in Ordnung
ABS/ASR-Regelgeraet tauschen
-------------------------------------------------------
Translation, hopefully correct:
- push brake pedal and ASC switch simultaneously
- Zuendung "an" / ignition on
- Bremspedal und Schalter loslassen /release brake pedal + ASC switch
- ASC-LEUCHTE faengt an zu blinken/ASC light starts to blink
BC = BlinkCode

BC 1 = kein Fehler / no fault
BC 2 = EMS Fehler / EMS fault
BC 3 = Motronic Fehler (DME/ EMU)/ DME/EMU fault
BC 4 = Drehzahlgeber Fehler hinten links/fault speed indicator rear left
BC 5 = Drehzahlgeber Fehler hinten rechts/fault speed indicator rear right
BC 6 = Drehzahlgeber Fehler vorne rechts/fault speed sender front right
BC 7 = Drehzahlgeber Fehler vorne links/fault speed sender front left
BC 8 = ABS-Magnetventil hinten links/ABS solenoid valve rear left
BC 9 = ABS-Magnetventil hinten rechts/ABS solenoid valve rear right
BC10 = ABS-Magnetventil vorne rechts/ABS solenoid valve front right
BC11 = ABS-Magnetventil vorne links/ABS solenoid valve front left
BC12 = ASR-Plungenventil Fehler hinten links/fault ASR plunger valve rear left
BC13 = ASR-Plungenventil Fehler hinten rechts/fault ASR plunger valve rear right
BC14 = Ventilrelais Fehler/ fault valve relay
BC15 = Rueckforderpumpen Fehler/ fault recycling pump
BC16 = Speicherladeventil Fehler/fault storage load valve
BC17 = Langzeitfehler Druckueberwachung/ long time fault pressure control
BC18 = Leckage Fehler (wird auch angezeigt wenn Druckspeicher (Gaspatrone) im ASC+T Hydraulikblock schadhaft ist (z. B. leer) leakage fault (is also shown when pressure vessel (gas bomb) in ASC+T hydraulic block is damaged (for example empty)
BC19 = Druck Fehler/ pressure fault
BC20 = Getriebebeinflussung Leitungsfehler/fault wire transmission control
BC21 = ABS/ASR-Regelgeraete Fehler/fault ABS/ASR regulators
BC22 = TD-Signal Fehler (duerfte Tachoimpuls sein) TD-signal fault (should be the speed impulse)
BC23 = Option pin Leitungs Fehler/option pin line fault

Zu/to BC 22:
TD Signal Fehler/TD signal fault
Regelgeraet Kl. 55/ regulator terminal 55
Zuendung aus /ignition off
Stecker vom ABS/ASR-Regelgeraet und Motronic-Steuergeraet Bank links abziehen/disconnect from the ABS/ASR regulator unit and MOTRONIC module bank left the connectors
Leitung vom ABS/ASR-Regelgeraet Kl.55 zum Motronic- Steuergeraet Kl.6 auf Unterbrechung/Plus-/und Masseschluss pruefen.
check the line from ABS/ASR regulating unit terminal 55 to MOTRONIC- control module terminal 6 for interruption/plus-/and ground connection
wenn i.O./ in case that is o.k.,....
Fehlerspeicher Motronic auslesen/read fault codes
wenn i.O./in case that is o.k.,....
ABS/ASR-Regelgeraet tauschen/change ABS/ASR control unit

No change.
Then changed the K10 X54 relay in the fuse box left side engine bay = ABS overvoltage protection relay https://www.autogenius.info/bmw-735i...e-box-diagram/
Bingo, that was the problem, he disassembled the relay + tested it, tested the other one to compare, same result, installed both relays one after one to test, both o.k., so it looks like the only problem was a bad contact or oxidation on the relay spades.


Stabilant 22A Electrical Contact Enhancer , Model: All BMW
Complaint: Connectors which carry low current are more likely to form deposits which affect the resistance of the circuit through the plug connector. Depending upon the particular circuit these deposits can cause malfunctions and consequently activate warning lamps and check control indicators.
Remedy: Part replacement can temporarily stop the problem. If the connector is the problem then without disconnecting the connector measure the resistance of the circuit running through the connector to make sure the connector has a high resistance. A good resistor will have close to 0 ohms resistance. Visually examine the male and female terminals in the connector housing by removing them. Look at the integrity of the wire crimps, and in some male terminals the integrity of the weld of the male pin to the terminal. Then reinstall. With a zero residue electrical contact cleaner liberally spray the male and female connectors, and allow the air to dry. Apply Stabilant 22A to both male and female terminals so they are saturated, and reconnect the connectors while they are still wet. When the Stabilant 22A dries it will leave a thin coating of polymer film which is conductive between mating surfaces, and is non-conductive between adjacent pins. It can also prevent the formation of more harmful deposits.
=================
Stabilant is a Canadian-made substance used to enhance conductivity while sealing out moisture. The VW part number is ZVW 186 001 STABILANT 22A. According to VW you should NOT apply Stabilant to oxygen sensor terminals.
If you disconnect a connector you must reapply Stabilant. Stabilant conducts electricity as well as a soldered joint. Stabilant has the interesting property of enhancing conductivity between two connectors but remaining a non-conductor between adjacent terminals in a multi-pin connector.

[Philax]

Dear all,
Thanks for all interesting advises regarding ABS issues. I had for years this ABS light ON every time I started running the car.
This means that ABS is OFF so less security in emergency cases.
I finally replaced the ABS control module (easy job : 5 minutes only) and light is OFF fortunately :-)
I start changing relays, sensors to all wheels, cleaned the reading parts of all wheels without success before

Hope this can help some other oldies BMW lovers.
Philax

[Smoky540i]

Good info Philax

[Annddrriy]

When I connect carsoft 6.5 to check ABS module it was not respond ? ABS light in't on.

[shogun]

I am not a carsoft expert, but I have read often, that it will not work perfect on the E32. Recently read on the German forum of a similar problem:
he could get:
DME: OK
Inst.Cluster: Module does not respond
SIM: Module does not respond
AIRBAG: Module does not respond
ABS/ASC: Module does not respond
BC/MID: OK
DWA: Module does not respond
ZKE/ZVM: Module does not respond
HKL: OK
EGS: OK
EWS, LCM/CCM, PDC, CVM, CAS, ZGM, RLS: Module does not respond
E32 750i built 12.1990
DME reading he could only DME1 cylinders 1-6, bank 2 cylinders 7-12 shows : Cylinder bank 2 : DME 2 does not respond

some info http://www.bba-reman.com/gb/content/...w_abs_problems

[Annddrriy]

Any idea how to disconnect ABS system but to not effect brake light when need to use it ? Thank You !

[shogun]

Never tried, I would fix the ABS. Fuses 1 and 17 are for ABS, but they are also for many other functions, fuse 17 exactly for 24 functions, fuse 1 for 10. So you cannot just pull the fuses.

[Annddrriy]

The ABS module not respond with diagnostic tool carsoft 6.5 and no light on dashboard but there is a problem I still looking for how to fix ABS module or this is something else related to ABS module like a wheel sensor or possibility wheel hubs got rust and not pick up correct reading from rusty hub rings. Maybe will buy GT1 interface with laptop to get better diagnostic.

[shogun]

maybe you start with a multimeter and test as per my post #1, check the front and rear sensor visually.
I once had a ABS problem front left, light was on, turned out the wire loom connector from the ABS sensor was broken, also found on other cars broken wires of the sensor.
Visual inspection is important too, not only laptop testing.

[Annddrriy]

That is good idea thanks.

[Annddrriy]

If disconnect ABS module from harness the brake light will work ?

[shogun]

I have never tried to disconnect the ABS and drive or start the engine and probably nobody else, do it and test it, or check the wiring diagrams http://shark.armchair.mb.ca/~dave/BMW/e32/
see 1990 diagrams page 3450-00/01/02/03, there you can see that there is a line to the main relay and injection, maybe you get some other trouble then.

[Annddrriy]

Transmission kick down switch. When accelerator pedal pressed all of way down kick down switch grounded or no ground ? What can happen if kick down switch not ground to the frame it get rust a lot ?

[shogun]

does your car have a EML system or not? M30 came with EML or normal throttle. There's no kick-down switch on the EML system of the M30 and M70, the pseudo kick-down signal is derived from the EML system when the throttle pedal output exceeds 70%. This signal is sent from the EML to the EGS.
test per Bentley if I remember right:
Pin 20 to ground.
Pedal at idle: .40
Pedal at full throttle: 3.8

In case your car does not have EML, check the wiring diagram for details and/or the Bentley repair manual

I checked for you, in case the M30 has no EML:
have a look at the kick down switch which is located behind the gas pedal., there you should have 5Volt, and when you push the kick down switch is is grounded. That you can measure at the transmission control module Pin 2 wire green/yellow.
Double check in the ETM by built year for your car.
Also check the throttle cable adjustment at the throttle, maybe wrong adjusted. Then the transmission does not get the kick-down signal. When yu open the throttle by hand completely, then just before it is fully open you should feel a very strong resistance! If not, adjust the throttle cable. See Bentley manual.