E46 330i DSC+Brake (?) light

Gaygle · 26 Nov 2009 at 09:56

Hi,

This morning, whilst sedately pulling away from some traffic lights, the DSC light (yellow) and what i think is the brake light (yellow) came on and i heard a beep. I pulled over straight away and looked in the manual and it said something about DSC+ASC malfunction.

The "brake" light looked like this (O) and had no ! in it or anything.

From looking around, i have seen that it could be a DSC module failure, DSC pressure sensor or steering wheel sensor, but i was wondering how i go about resolving this? The concensus seems to be "just wait until it comes on again" as it could have just been an anomally.

Questions:
-I was going to take it to BMW, but being inexperienced with dealerships, do they charge to diagnose?
-Is it worth notifying the place i bought the car from? They told me that if there is any issues, notify them before notifying the warranty (AA) company as they can normally twist their arms into doing work that isn't covered.
-Do warranty's normally cover DSC failures/sensors? I have looked at the policy and it doesn't mention anything to do with DSC failures, only ABS or brake failures.

thanks

PMKeates · 26 Nov 2009 at 10:31

I would take it to the dealer, and just be nice about it. Clearly something's wrong.

It could be an ABS sensor. Hope for that. They are cheap and easy to replace. Then it's the steering wheel sensor, not so cheap and not so easy, but palatable. Then it starts rapidly getting very expensive from then on.

You can diagnose ABS sensors yourself. Drive along, stamp on the brakes. If the wheels lock, it's an ABS sensor. If ABS cuts in, I'm sorry, it's going to cost a bit

Additionally, if it's not ABS, have BMW or a good specialist with the appropriate BMW equipment diagnose it. BMW will charge a small fee if you don't have it repaired there. The majority of garages will maybe think they can find they fault, but they likely won't.

[TW]Fox · 26 Nov 2009 at 10:47

Probably a wheel speed sensor, but could be the hydro unit I guess.

Gaygle · 26 Nov 2009 at 11:24

PMKeates said:
I would take it to the dealer, and just be nice about it. Clearly something's wrong.

It could be an ABS sensor. Hope for that. They are cheap and easy to replace. Then it's the steering wheel sensor, not so cheap and not so easy, but palatable. Then it starts rapidly getting very expensive from then on.

You can diagnose ABS sensors yourself. Drive along, stamp on the brakes. If the wheels lock, it's an ABS sensor. If ABS cuts in, I'm sorry, it's going to cost a bit

Additionally, if it's not ABS, have BMW or a good specialist with the appropriate BMW equipment diagnose it. BMW will charge a small fee if you don't have it repaired there. The majority of garages will maybe think they can find they fault, but they likely won't.

I should mention that as soon as i turned off the engine, and turned it back on the lights stayed off for the remainder of the journey (10mi). I was under the impression that it is unlikely to be the ABS because this would make the DSC, Brake AND ABS lights illuminate. If it is the ABS sensor, i will literally cry - i've been trying to get rid of my old Primera, but it seems like an ABS sensor has died on it as well. I HATE ABS.

So, if i take it to BMW, they will read the fault and charge me for the fault reading only if i don't get it repaired there?

[TW]Fox;15400019 said:
Probably a wheel speed sensor, but could be the hydro unit I guess.

You have a price for both of those parts? I don't know if this is related, but i noticed a very irritating rattle from the steering column today, that i haven't noticed before.

[TW]Fox · 26 Nov 2009 at 11:27

Wheel speed sensor is about £150 a hydro unit + fitting £1500.

BMW will bill you for diagnostics whether you get the work done or not.

Gaygle · 26 Nov 2009 at 11:49

[TW]Fox;15400281 said:
Wheel speed sensor is about £150 a hydro unit + fitting £1500.

BMW will bill you for diagnostics whether you get the work done or not.

Thanks for the info. I guess i'm praying it's either just an anomally or a wheel speed sensor. How much do BMW charge for a diagnostic? I hope it's nothing like Nissan who wanted £115 just to plug it in.

[TW]Fox · 26 Nov 2009 at 11:52

Usually about £30-40.

There are places which can repair failed hydro units for between £200 and £400.

If you are worried about cost of diagnostics take it to a reputable independant. If they are trying to win your regular custom they might diag it for free.

NVP · 26 Nov 2009 at 14:09

[TW]Fox;15400019 said:
Probably a wheel speed sensor, but could be the hydro unit I guess.

Wheel speed sensor is just one warning light and is different to those described (Instead of it being a ! inside a cirlce and enclosed in brackets, it is actually a ! underlined with a squiggle and enclosed in brackets).

It looks to me as being a malfunction with the DSC as when the traction control system is switched completely off then both the OP described lights appear, but I don't have the vaguest idea as to what would be the cause.

[TW]Fox · 26 Nov 2009 at 14:10

Faulty wheelspeed sensors will also trigger the DSC light as when the sensor throws a fault it'll disabled DSC.

NVP · 26 Nov 2009 at 14:15

It disables the DSC?! Why does it do that? Surely that is dangerous? Or does it not actually disable it but just through up the warnings so that you get the car checked?

But even so, I assume that if it is a faulty wheel speed sensor then the wheel speed warning light would appear as well...?

EDIT: Examples of warning lights:
DSC lights

Tire Pressure/Run flat indicator light

vemp_0906_02_z+tire_pressure_monitoring_system+warning_light.jpg

[TW]Fox · 26 Nov 2009 at 14:19

It disables DSC because part of the system is not functioning, therefore the system is disabled (What if the faulty part failed to send the correct signal and the system kicked in when it wasn't supposed to?).

The DSC light illuminates when the system is not functioning (Whether manually by pressing the button or due to a fault). The ( ! ) icon indicates that Dynamic Brake Control (Part of DSC) is also not functioning (ie the entire system is disabled).

The second warning light is nothing to do with DSC. It is the Tyre Pressure Warning light - it warns of a tyre thats under pressure.

There isn't a wheel speed sensor warning light. I really suggest you familiarise yourself with what the lights mean - both for your own peace of mind and also if you intend to give advice on what the lights mean to others.

NVP · 26 Nov 2009 at 14:23

[TW]Fox;15401600 said:
It disables DSC because part of the system is not functioning, therefore the system is disabled (What if the faulty part failed to send the correct signal and the system kicked in when it wasn't supposed to?).

The second warning light is nothing to do with DSC. It is the Tyre Pressure Warning light - it warns of a tyre thats under pressure.

Oh I see! I thought the "wheel speed sensor" you referred to was the same one which diagnoses the tire pressure/run flat as they are calculated by the number of rotations made over a certain time.

Sorry, my confusion.

EDIT: Sorry to derail the topic slightley but Fox could you explain "Dynamic Brake Control" please? Or do you have any links to a good description of the entire DSC system I could read up on? Cheers

[TW]Fox · 26 Nov 2009 at 14:24

Some of the tyre pressure control systems do use the wheel speed sensor to calculate whether a tyre has punctured, yes. But he has a 2002 330i Sport and it's very unlikely his car is fitted with tyre pressure control. anyway, so he wont have this system.

Howard · 26 Nov 2009 at 14:26

nuvpal said:
It disables the DSC?! Why does it do that? Surely that is dangerous?

I think I'd rather have disabled DSC than potentially faulty, funky DSC

NVP · 26 Nov 2009 at 14:27

[TW]Fox;15401636 said:
Some of the tyre pressure control systems do use the wheel speed sensor to calculate whether a tyre has punctured, yes. But he has a 2002 330i Sport and it's very unlikely his car is fitted with tyre pressure control. anyway, so he wont have this system.

OK my bad, sorry if I confused you even more Gaygle.

Howard said:
I think I'd rather have disabled DSC than potentially faulty, funky DSC

Yeah I get it now, I didn't realise that the wheel speed sensor Fox was referring too was part of the DSC, I thought it was for the Tire pressure/Run Flat indicator.

PMKeates · 26 Nov 2009 at 14:31

nuvpal said:
EDIT: Sorry to derail the topic slightley but Fox could you explain "Dynamic Brake Control" please? Or do you have any links to a good description of the entire DSC system I could read up on? Cheers

http://www.kinmak.com/downloads/doc/m3training/TSC1.pdf

56 pages on DSC

DBC is an interesting function, and feels weird. A car once threatened to pull out shortly in front of me as I driving along a back lane. I rammed the brake on hard and fast the moment their car rolled forward, and then they stopped, so I let off the brake. The car didn't - it kept braking for about another second or two, holding the pedal to the floor!

NVP · 26 Nov 2009 at 14:37

Cheers PMKeates! Will be a good/interesting read after work. Thanks.

Gaygle · 26 Nov 2009 at 16:21

nuvpal said:
DSC lights

Yeh, these are the lights that came up (and there was a beeeep) (the same as if you hold down the DSC button for 5 seconds).

Also, i do have Tyre Pressure Control but that light didn't come on when the fault occurred.

I went for a drive for an hour at lunch and no lights/nothing abnormal occurred, but just to be safe i've got it booked into a BMW specialists tomorrow with the proper BMW diagnostic equipment so hopefully should find out what was wrong.

They're also checking out the rear heated screen (FOC!), because when it's activated, it kills the radio signal and just gives it static. Looking around, it seems this is quite a common problem, and i'm just hoping that the elements in the rear screen are faulty so it can be replaced under warranty.

[TW]Fox · 26 Nov 2009 at 16:23

Gaygle said:
They're also checking out the rear heated screen (FOC!), because when it's activated, it kills the radio signal and just gives it static. Looking around, it seems this is quite common problem, and i'm just hoping that the elements in the rear screen are faulty so it can be replaced under warranty.

Had this on the 530d. Required replacement rear screen under warranty.

Most aftermarket warranties specifically exclude audio equipment cover.

Gaygle · 26 Nov 2009 at 16:27

[TW]Fox;15402407 said:
Had this on the 530d. Required replacement rear screen under warranty.

Most aftermarket warranties specifically exclude audio equipment cover.

Unfortunately, the guy said that if it can't be proven that the elements in the rear heated screen have failed, then AA won't replace it under warranty. Tomorrow, i'm getting them to check the elements as well as the little aerial box within the N/S C pillar, so at least i know the root of the problem. It's not a big thing, as i normally listen to CD's/iPod, but just want to get it sorted.

I was wondering though, would i be able to get it replaced under insurance? Obviously i'd have to pay the excess.