ABS not working. No error codes or lights

[mrscalex]

Strange one this and I'm not sure where to go with it. Btw it's not a regular ABS warning lamp on what do I do. I've fixed and reprogrammed replacement modules various times to fix that.

I was aware previously the ASC button was doing nothing which seemed strange. And I've never seen the traction light come on in use. So I had my suspicions.

The MOT tester has now pointed out that the ABS warning light is not coming on when the ignition is activated. This clearly suggests it's not passing required start-up checks. I hadn't in all honesty spotted that light not coming on previously.

So I've got to conclude the ABS system is not operational.

Here's the big BUT though. The dash warning light does not come on in use (and as above it doesn't come on during ignition. AND there are no error codes.

I could just change out the ABS module and that's about all I can think of at the moment. But I previously replaced it because it was throwing an error and it coded up with no problems which I wouldn't expect if it was duff.

I guess there's a possibility too the warning light is blown and the resistance is high causing the system not to power up. But then you'd think there would be an error code.

So I have 2 things to try but experience tends to tell me if there's no logic to why you are replacing something it probably isn't going to fix it.

I'm at a loss as to what is going on! Ideas please!

 

[Sean d]

Is there a bulb in it as it may have been removed in the past, not a clue as to why its not showing any error codes

 

[mrscalex]

Is there a bulb in it as it may have been removed in the past, not a clue as to why its not showing any error codes

The best lead I've got at the moment is that it's the bulb blown and is shutting down the system. I've now found out that is normal practice on an E36 at least.

https://www.bimmerforums.com/forum/showthread.php?2353198-ABS-light-not-illuminating-help/#12

I still struggle with the fact it's not throwing an error code. If it knows the bulb is blown or absent why can't it put an error out?

Maybe if a bulb error is detected it doesn't even try to establish communication with the module. Which could mean there is an underlying error being concealed and waiting to be discovered. Which might also mean a previous owner removed the bulb to disguise it.

I am starting to question myself if I did replace the ABS module now as I've done it on so many cars. If I didn't then it would fit the explanation better as it would mean I hadn't after all definitely seen the warning light on.

 

[NZ00Z3]

..

 

[mrscalex]

Can you activate the ABS unit with your scanner? I do this with INPA. This will tell you if the ABS unit is functional.

The idea that the bulb might be the problem has the biggest possibility at the moment.

Very fair point as regards INPA. I shall add that to the list. Thanks.

 

[Mario]

Hello - I have had to fix a similar problem, ended up being the previous owner "masked" a problem with the DSC sensors by cutting the track that drives the DSC light on the binnacle/cluster motherboard and wiring a small cable to another light, it appeared "operational" but the DSC was showing faults. I could fix the motherboard. Your issue seems to be different but if you plug INPA and it does not show faults or you can run tests to "purge" the DSC pump from DIS I believe I would start looking at the binnacle, maybe replace it with a "known" good one and see if that works. you can also see if the button works on INPA if you look on digital values on the DCS section. Hope it helps Robert.

 

[mrscalex]

Hello - I have had to fix a similar problem, ended up being the previous owner "masked" a problem with the DSC sensors by cutting the track that drives the DSC light on the binnacle/cluster motherboard and wiring a small cable to another light, it appeared "operational" but the DSC was showing faults. I could fix the motherboard. Your issue seems to be different but if you plug INPA and it does not show faults or you can run tests to "purge" the DSC pump from DIS I believe I would start looking at the binnacle, maybe replace it with a "known" good one and see if that works. you can also see if the button works on INPA if you look on digital values on the DCS section. Hope it helps Robert.

Appreciated thank you.

 

[Mario]

Appreciated thank you.

Hope it works, let us know what you find

 

[Dino D]

Hello - I have had to fix a similar problem, ended up being the previous owner "masked" a problem with the DSC sensors by cutting the track that drives the DSC light on the binnacle/cluster motherboard and wiring a small cable to another light, it appeared "operational" but the DSC was showing faults. I could fix the motherboard. Your issue seems to be different but if you plug INPA and it does not show faults or you can run tests to "purge" the DSC pump from DIS I believe I would start looking at the binnacle, maybe replace it with a "known" good one and see if that works. you can also see if the button works on INPA if you look on digital values on the DCS section. Hope it helps Robert.

Totally off topic: sneaky but clever, I see a new service for exactly this coming up on eBay soon now that the EML light is a MOT failure...

 

[Mario]

Totally off topic: sneaky but clever, I see a new service for exactly this coming up on eBay soon now that the EML light is a MOT failure...

Very dangerous too since you think the DSC is operational but in reality it's disabled.. Potentially a criminal offence if someone dies as a result of failure to tell the future owner of this "hack", I spent weeks trying to tackle the problem of a "faulty" dsc button until I happened to stumble onto the cable

 

[mrscalex]

Very dangerous too since you think the DSC is operational but in reality it's disabled.. Potentially a criminal offence if someone dies as a result of failure to tell the future owner of this "hack", I spent weeks trying to tackle the problem of a "faulty" dsc button until I happened to stumble onto the cable

We don't know what the cause of my issue is yet - I'm getting the car back to look tomorrow.

But if it is the bulb removed or a similar hack I 100% agree with you. It had completely pulled the wool over my eyes.

And if it's not a hack (come to think of it regardless) someone at BMW needs a telling off for designing a car that fails to give an error or warning lamp signal that the system is not operational.

What kind of design is that? Bulb blown (let's assume) > shut down system > give absolutely no indication that either has happened. Okay the ASC button does nothing but I foolishly assumed it was broken and just not turning the system off.

It's just as well the MOT tester was doing things by the book and looked for the lamp coming on during ignition. I had completely missed this since I had the car. So did the MOT tester last year as the fault was almost certainly there last year.

I look forward to getting to the bottom of this one!

 

[mrscalex]

Oh, look what’s missing.

11 & 19 which are the ABS bulbs.

And the irony? They went out immediately after indicating no error. I must have fixed whatever was wrong when I rebuilt the car last year. Probably the wheel sensors which I routinely replaced.

 

[Mario]

Good to know that you have fixed it. Happy motoring Robert

 

[the Nefyn cat]

Nice when it's something simple, ain't it? Now onto the next problem.

 

[mrscalex]

Yes. But it’s only simple because with the assistance of other forum members logic was applied before diving in.

I could equally have started swapping stuff out but it seemed to make no sense and now we know why.

Can you imagine if someone had taken it to certain garages? They could have been changing system components like sensors or even the pump/module and running up a big bill. Or worse still spotted it put the bulbs in and charged £200 for it claiming it was something major.

 

[the Nefyn cat]

Know what you mean, I've seen people going out and buying stuff in the hope that if they change everything the problem will just disappear. And then you find a dodgy earth/something similar by using logic. That's the sort of thing I was taught during my apprenticeship, and it still works (most of the time) today. When it's an Army apprenticeship, you WILL learn.

 

[Mario]

Yes. But it’s only simple because with the assistance of other forum members logic was applied before diving in.

I could equally have started swapping stuff out but it seemed to make no sense and now we know why.

Can you imagine if someone had taken it to certain garages? They could have been changing system components like sensors or even the pump/module and running up a big bill. Or worse still spotted it put the bulbs in and charged £200 for it claiming it was something major.

I have had this happening on 3 different cars either with the DSC/abs lights, airbag lights or the engine check light where previous owners or unscrupulous garages have removed or rigged bulbs on the dash.

On my 3.0 before my ownership a garage diagnosed and fitted a new dsc switch under the previous ownership, another garage charged for diagnostics a few years earlier for the same problem.dash was rigged and modded to simulate the light was working to mask a problem with the very expensive rotation sensor

Moral of the story, check with the computer first, you can test most if not all components separately including the dash lights by looking at digital values on impa

 

[mrscalex]

Moral of the story, check with the computer first, you can test most if not all components separately including the dash lights by looking at digital values on impa

Well in my case I had found errors on the ABS looking at the diagnostics a year ago, fixed them and assumed it was all working.

Are you saying missing dash bulbs are reported by INPA? Or that INPA can be made to turn all the dash lights on at once to check?

 

[g8jka]

There should be a way of testing the instrument cluster to check that all needles, bulbs etc work as they should. If the bulb doesn't light up it's most likely blown or removed by a previous owner. It's actually quite handy that it's now an MOT testable item, you may never had noticed otherwise. Nice easy fix

 

[Brian H]

There should be a way of testing the instrument cluster to check that all needles, bulbs etc work as they should. If the bulb doesn't light up it's most likely blown or removed by a previous owner. It's actually quite handy that it's now an MOT testable item, you may never had noticed otherwise. Nice easy fix

There is a way to do this, you can put the cluster in to test mode and select one of the functions to check dials and lights.