ASC light always on. What could be the problem?

[Fatandre]

Hey guys. I am having a problem with my ASC light as it is always on.
Only the ASC light and I cant turn it of with the button.
What should I look into?

[uinvyme]

Mine does it sometimes. I think it's related to voltage or the unit possibly on its way out. Normally happens on a restart from the daily run, never on the initial cold start

Sent from my SPH-L720 using Tapatalk

[alex840]

Are you getting anything on your MID/OBC? I had the speed sensor (expensive) break off. Driver side, if I recall correctly.

Hey guys. I am having a problem with my ASC light as it is always on.
Only the ASC light and I cant turn it of with the button.
What should I look into?

[TxGR8White]

Look into:
- wrong size wheel and tires (they can't be more than 3% different between front and back)
- dirty/broken speed sensor on each wheel
- failed ASC+T Hydro pump (if your car has ASC+T)

[Fatandre]

Look into:
- wrong size wheel and tires (they can't be more than 3% different between front and back)
- dirty/broken speed sensor on each wheel
- failed ASC+T Hydro pump (if your car has ASC+T)

Just to be clear its only the ASC light
I have asc T
It also happens with stock wheels and tires.

[TxGR8White]

Your ASC+T Hydro Pump has failed - good luck, those are hard to find.

[Black88GTA]

Has this car been sitting for a while? Mine did this after sitting a few months, and the "fix" was to drive through a couple puddles enough to (I assume) clean the crap off the wheel sensors. I think rust had built up on the rotors while sitting, and when I took it out for the first time after that all of it got scrubbed off and ended up on the wheel sensors.

[alex840]

-Mine was: broken speed sensor
-failed ASC+T Hydro pump (if your car has ASC+T). I have one on my parts car, but someone called DIBs already. If they don't come through, I will let you know.

Look into:
- wrong size wheel and tires (they can't be more than 3% different between front and back)
- dirty/broken speed sensor on each wheel
- failed ASC+T Hydro pump (if your car has ASC+T)

[tangcla]

Check the ASC cable. My cable had frayed and that caused the cable to 'stick', and made the ASC light come on.

[Timm]

Give it a poke - they usually get going again:

[Fatandre]

So i should Just make a hole in the relay and poke it with a screwdriver ?

[TxGR8White]

So i should Just make a hole in the relay and poke it with a screwdriver ?

That is like asking if you should jam a screwdriver through the fender into the Hydro pump and see if it fixes itself - we narrowed it down for you. You now need to do actual diagnosing on your vehicle and find the problem. When I had this problem 10 years ago, I narrowed down to the Hydro Pump and had to pull it and replace it. You can check the 4 wheel sensors pretty easily. The sensor itself rarely fails, but you need to look at the wiring too. Usually it is just dirt build up on the magnet - clean them off and see if the light goes out. If it doesn’t, then you will most likely need a new ASC hydro pump.

[Fatandre]

-Mine was: broken speed sensor
-failed ASC+T Hydro pump (if your car has ASC+T). I have one on my parts car, but someone called DIBs already. If they don't come through, I will let you know.

Let me know
Did how is your csi ?

[Timm]

That is like asking if you should jam a screwdriver through the fender into the Hydro pump and see if it fixes itself

Ooohhh! That's a bit of a slight for us Shadetree mechanics! But I also realize that you have an early 850, so the relay is not where it is on the 840 anyway....

[pollack138]

Suggest check asc codes and go from there (http://www.bimmerboard.com/forums/posts/213216).

[TxGR8White]

Ooohhh! That's a bit of a slight for us Shadetree mechanics! But I also realize that you have an early 850, so the relay is not where it is on the 840 anyway....

Fatandre has an 850....

[ChrisFuture8]

On my car, the MID displays the "Brake Assist" message and "Check" message. The cluster shows the (!) indicator. It comes on and goes off on a regular basis.
The funny thing is, every time when I flip the headlights, the "Brake Assist" message and (!) lamp on the cluster comes on right away. I had a leak in the pentosin system that I have recently fixed and have bled the system via the valve by the shock tower on driver's side.
The brakes are very mushy so I need to bleed the brakes. Not sure why turning on the headlights would trigger the Brake Assist warning to come on the MID.

[Diskovod]

Fatandre, start the ASC self-diagnostic.
I've read the manual, it was pretty easy.
It will blink on the dash, and you'll see.

I don't remember, you need to turn ignition with ASC button pressed for 10 seconds or something like that.


In my case, a very odd one, the system did not like the ASC+T/ABS control module. So it blinked to the last error - control module.
Everyone told me it must be an ASC+T pump. Nevertheless, I bought a spare ASC+T/ABS control module, installed and it was fixed.
The fun thing that the ASC module didn't answer to normal service tool diagnostics via the round plug. So self-diagnostics works!

p.s. For your interest, I've opened up the ASC+T/ABS module and it looked scary and perfectly fine. The scary thing is that there are many gel-celled processors, and it's all "made in Austria" which you don't see often.

[Fatandre]

Thanks Diskovod.
How do you read the blinking?

[Diskovod]

Here are the instructions
https://imgur.com/a/hWxkyaZ











Please, save the images, it's likely they won't last forever, and they exceed bimmerforums size quota.

[clockwork]

sadly I replaced my tandem pump for my ASC+t system and it seemed to fix the ASC+t light form coming on for months, then again it came back.
I'm looking to see why its back.
Have you bled your pentosin system properly by disconnecting the ABS module connection then bleeding the ASC+t nipple back into pentosin reservoir? I just did it again and it definitely helped make my steering groan a lot less again and braking somehow seems a little crisper, but still did not solve my ASC+t light, which comes on only after the car heats up. Never on a cold start.

[cartoonz]

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[72tpik5]

As if an 8 needs ASC+T. I can't imagine a driving condition when it would be necessary. I am considering disabling mine.

[clockwork]

Give it a poke - they usually get going again:

sadly, my 03/90 build will not connect and allow INPA to perform this test.

[Fatandre]

What is it that gets damaged in the ABS- ASC T unit?

They are pretty hard to source