Technical Braintrust --> Anti Lock Dash Light ON! (13 years long issue)

[CamayroZ]

Hello E30 folks,
30 years long '88 owner here with a very nice low mileage car.

I have a 2" binder of all the receipts for the car going back to when it was purchased new at Schomp BMW in Denver.

I have been chasing an issue on/off since 2009 with NO FIX! The Anti-Lock dash light would come on within a few miles of driving the car. I had the BMW dealer try repairing it a few times and they failed, only wasted my money and time. Here is a summary of what was done, and I can use your help:

June 5, 2009:

+ replaced Pulse generator: 34-52-1-178-982
+ replaced Pulse generator: 34-52-1-178-981
+ Replaced Relay: 34-52-0-000-192

April 3, 2010:

+ Replaced Pulse generator: 34-52-1-182-067

April 27, 2010:

+ New ABS Module: 380175699197 (manufacturer's PN)

June 3, 2010:

+ Dealer gave up and suggested removing the bulb!!!!

October 20, 2017:

+ (at another BMW dealer!) New Pulse generator: 34-52-1-155-041

So...multiple visits over a period of 13 years or 3,000 miles and probably $1,500 wasted.


Here is what I have learned:
+ Ignition off, if I start the car and go STRAIGHT line, it will take a mile for the Anti-Lock dah light to come on.
+ Ignition off, if I start the car and do a tight turn, the Anti-Lock dash light will come on immediately.


I don't the drive the car much, so I can jack it up and try all your ideas!!! But I will never take this car to a BMW dealer again if I can help it.

Thank you in advance!!!

PS: I am trying to attach a picture but continue to get this error "An unexpected error was returned: 'Invalid image geometry'" :( Anyone know why?!!!

[jimmy p.]

Unless I have missed something in the previous attempts to repair, it seems like the only thing left is the 4 corners of wires leading to and from the ABS units. You have changed everything else.
The E30 ABS system is a reluctor wheel, so it generates a voltage signal to the computer.
It seems to me after that you have changed all the components other than the wires all thats left to check is the wires.

My guess is once you start driving one of those sensors is not sending the same voltage to the computer as the others consistently thus tripping the light.
Have you resistance checked all the lines leading from the sensor plugs to the mass connector on the ABS unit?
Thats where I would start.

[jimmy p.]

Hey one other thought,,, along the way of your ownership did anyone ever change a front wheel hub for the much more commonly used E28 hub and forget / neglect to change the reluctor wheel with the original E30M3 one?
That are completely different resolutions and that would easily trip up the ABS computer.

[1990m3]

Hey one other thought,,, along the way of your ownership did anyone ever change a front wheel hub for the much more commonly used E28 hub and forget / neglect to change the reluctor wheel with the original E30M3 one?
That are completely different resolutions and that would easily trip up the ABS computer.

Ding Ding Ding -- at least that's my closest guess at this point. Or possibly a damaged ABS ring is an option too.

[mlytle]

yup. either of those things. both are simple to check. eyeball the abs rings, and continuity check the wires to each sensor from the brain.

[CamayroZ]

jimmy p. I appreciate the thoughts, this is what I know:
1) I do not think that anyone has replaced the hub with E28 hubs. I have owned the car for 30 years, and I did not have had a reason to make the change; and I have looked through all my receipts and do not see a hub change, plus, this issue just started in 2009, so as an owner it was OK from 1991 to 2009. --> I need to jack up the car and remove all wheels and start this diagnostics process. --> Can you tell me if there is a visual cue for E28 hubs?

2) I understand the variable reluctance sensors (two wire? Mag. pick up type?); So, I will "Ohm" them and see. Is there a diagnostic tool to read the codes and to tell which wheel end maybe the issue? Also, in my own recent diagnostics, a tight turn sets the light off very quickly. Can this point to front sensors?

I do not have a service manual for the car, so I will do more research to find out more...


mlytle Thank you...the brains are inside the cabin? Possibly under the dash?

[mlytle]

https://www.e30zone.net/e30wiki/index.php/ABS_Problems

https://www.r3vlimited.com/board/forum/e30-technical-forums/general-technical/378404-abs-light-on-e30-gurus-please-help-problem-solved

https://www.r3vlimited.com/board/forum/e30-technical-forums/suspension-unsprung/brakes-subframe-arms/259135-causes-for-the-abs-light-to-stay-on?t=291172

[Mick]

Can you tell me if there is a visual cue for E28 hubs?

Here's a thread with an image of them side by side. It will be obvious just by looking at them if you have 2 different ABS rings.

https://s14net.vbulletin.net/forum/s14/general-e30-m3-discussion/22585-e28-front-wheel-bearing-swap

[jimmy p.]

jimmy p. I appreciate the thoughts, this is what I know:
1) I do not think that anyone has replaced the hub with E28 hubs. I have owned the car for 30 years, and I did not have had a reason to make the change; and I have looked through all my receipts and do not see a hub change, plus, this issue just started in 2009, so as an owner it was OK from 1991 to 2009. --> I need to jack up the car and remove all wheels and start this diagnostics process. --> Can you tell me if there is a visual cue for E28 hubs?

2) I understand the variable reluctance sensors (two wire? Mag. pick up type?); So, I will "Ohm" them and see. Is there a diagnostic tool to read the codes and to tell which wheel end maybe the issue? Also, in my own recent diagnostics, a tight turn sets the light off very quickly. Can this point to front sensors?

I do not have a service manual for the car, so I will do more research to find out more...


mlytle Thank you...the brains are inside the cabin? Possibly under the dash?

1) If you never had a front hub changed then that is not the problem.
The reason it popped into my head was if you had it would have defied all the diagnosis that you have had done, and could easily have gone unnoticed, but its a non-starter if your car still has both its original front wheel bearings. ---BUT--- As Dave posted, do not discount a damaged ABS ring, that could also do it.

2) you have already seemingly changed out all the wheel speed sensors so its probably not them, if it were me I would be focusing on the actual wires from the plug at each wheel speed sensor to the large mass connector at the ABS computer (which is under the dash by your left knee).
Get the pin out from the ETM and test each conductor from the plug to the connector --- and --- if they are all all the same, start wiggling stuff LOL.

No I dont think the turn triggering "necessarily" points to a front sensor because the two rear wheels are traveling at different speeds in a turn as well so the discrepancy could be in the rear as well.
It "could" be a front one in that in a turn the front struts where the ABS wires are attached articulate, which in turn pulls on the ABS wires so there could be a damaged chassis side wire that shows up when those struts fully articulate.

There are no codes anywhere on any E30M3, its a very analog car (1984 technology). A DMM is your weapon of choice here.

DATA POINT: On my 1988 street car I just re-wrapped all the ABS wires on the chassis. The jacketing was in horrible condition, all the wires were exposed or about to be.
The outer jacket was literally crumbling off and my car has been garage kept and only driven under pretty charmed conditions since 1994.
I see similar deterioration in almost every single E30M3 that gets posted for sale on BAT.

Good luck.
Cheers
Jimmy P

[Dave @nz]

Hi,
I agree with the above points remove all 4 wheels visual check the reluctor rings also make sure clean and free of rust, not sure if you could prod them with a screwdriver just to confirm that one is not free spinning on the hub.
The rear ABS wiring and plugs are under the rear seat so dont think they would be a problem.

[CamayroZ]

^ I appreciate all the input here...I will be getting after it this week, to hopefully once and for all get this problem resolved.

Are there any Mods on this forum? I am trying to post some pictures of the car to share but I continue to get an error: "An unexpected error was returned: 'Invalid image geometry'"

[RAD2LTR]

^ I appreciate all the input here...I will be getting after it this week, to hopefully once and for all get this problem resolved.

Are there any Mods on this forum? I am trying to post some pictures of the car to share but I continue to get an error: "An unexpected error was returned: 'Invalid image geometry'"

Are you trying to directly upload the image, or link it from somewhere? If trying to directly upload, it might be too big of an image.

Will

[mwagner10702]

I am trying to post some pictures of the car to share but I continue to get an error: "An unexpected error was returned: 'Invalid image geometry'"

I get the same error message. I have noticed others who have tried posting pictures mention they get the same message. Something is effed up on the server side would be my guess.

I have a Onedrive account and host my pictures there. Onedrive has a tool that lets you embed pictures into sites like this. Other photo hosting sites probably have similar options / tools. This is what I would recommend if you want to post pictures.

[CamayroZ]

I get the same error message. I have noticed others who have tried posting pictures mention they get the same message. Something is effed up on the server side would be my guess.

I have a Onedrive account and host my pictures there. Onedrive has a tool that lets you embed pictures into sites like this. Other photo hosting sites probably have similar options / tools. This is what I would recommend if you want to post pictures.

Yes, something is screwed up with this website and "uploading" pictures of any size or type does not work...I wasted an hour on this! And I am not smart enough with Onedrive or other fancy stuff :(

Anyhow, back on the subject, I will be working on trouble shooting the ABS system this coming weekend.

Thank you again

[CamayroZ]

Hey one other thought,,, along the way of your ownership did anyone ever change a front wheel hub for the much more commonly used E28 hub and forget / neglect to change the reluctor wheel with the original E30M3 one?
That are completely different resolutions and that would easily trip up the ABS computer.

Here's a thread with an image of them side by side. It will be obvious just by looking at them if you have 2 different ABS rings.
https://s14net.vbulletin.net/forum/s...l-bearing-swap

Mick, jimmy p. et all...

Update here:

Time has been a challenge with too many projects, but this car is now on the top of my que...I finally raised front end, removed wheels, and looked at the front ABS tone wheels, and both side look the same and awfully like the E28 tone wheel shown in the above thread! They appear to look like a "fine" tooth ring.

I then went back and looked through my receipts which goes back to new, and in 2008 I purchased from Turner Motorsports new Front Wheel Bearings with ABS (E30M3 must use old ABS Ring); P/N: 31211468752. I had a good friend helping me on "easy" stuff, and wonder if I did not swap the ABS wheel? This is when "Anti-Lock" dash lights started to come on... Maybe this is it?

I think that the next step for me would be to remove the front hubs and verify?

If this appears to be the case, can these Tone wheels be procured?

Too bad I cannot post pictures here! :(

Thanks again.