Car in garage for over 2 months

[Nutgrove]

Hi, My 2001 BMW went into an independent garage in mid-November for a service, MOT, and new front brake discs (because there was slight vibration under breaking on the motorway). After they finished the service and disc change, it failed the MOT on brake imbalance. They replaced the brake calipers, but no difference, and after trying a replacement ABS unit in the car they sent the original off for testing which came back as 'ok'. They exchanged a 'boost pump' and also the master cylinder. They replaced the brake calipers again just in case they were a duff set, but still no improvement. There is now another problem in that the ABS light comes on after reaching about 20mph, and they can find a problem. They took it to the BMW main dealer who suggested exchanging the ABS unit again, but the garage decided this was not necessary as this had been done already. They are still working hard trying to solve the problem, but I am beginning to feel that a brake problem really shouldn't take this long to solve. I'm not really sure what to do! I can't really take it off them as they know what's been changed and another garage may have to start again. I wish it could go back to how it was before it went, but the abs light must be related to something which has happened in the last two months. Does anyone have any suggestions please?

[MegaCraggy]

when you say slight vibration under braking, did you feel it through the car or the steering wheel? have they checked the brake hose pipes, it might be worth replacing them, and have they inspected the rear brakes for any possible faults.

 

2 months is ridiculous to fix this, i would really consider taking the car somewhere else and have them look at it, they have actually added to your predicament by causing a fault with the abs, i'd hate to think how much this is costing you.

[Nutgrove]

Hi - thanks for the reply. The vibration under braking was through the steering - it was classic warped discs vibration. They have replaced all the flexi hoses and also the rear discs and pads too. The problem is that I won't want to pay anything to the current garage without the car being fixed, and as there is the new problem with the abs, is this something caused by what they have done or not? It's hard to say, although they have had the whole braking system to pieces etc.

[MegaCraggy]

howare they testing the imbalance after each component has replaced, road test or rolling road, or both?

[heliosuk]

This is a classic case of not following correct procedure in bleeding the braking system, especially more so since changing the ABS modulator. You can't do it properley without having it hooked up and electronically opening the valves in a set sequence. It's nothing like it used to be in the good old days.

 

Once this has been done road test. The swop wheels front to back and balance. Road test again and it still evident then start measuring run out and wear pattern on surface of discs under a magnifying glass.

 

A pad change could be in order as well as it's not unknown for varience in compressibility of the linings predominantly on metal sintered pads.

 

I also take it that routine things like steering and suspension joints are ok as are the run out on the wheels and tyres.

[Conniff]

Would certainly have the front bushes checked it the vibration is there after a disc and pad change.

[Nutgrove]

I don't think there is vibration now, but as I haven't had it back I don't know how it drives now. Brake balance has been measured on the MOT rolling road, and the system is being bled electronically as they are a proper Bosch service centre. The problem is the ABS/DSC light coming on and there not being a found cause for this. There is a £600 new Bosch ABS valve block on it's way from Germany now, so if this doesn't solve the issue, do I have to pay for it? It is a Bosch system in the hands of a Bosch service centre - I can't understand how it can be unsolvable.

[heliosuk]

None of these issues is insolvable and provided the correct process is followed there should be none.

 

However, the fact that ABS light and now DSC light come on is significant.

 

The first thing to check, which is not in the manuals, is to check the wheel diameter at the tyres.

 

I've posted it before but all 4 wheels have to be within a certain percentage of each other, otherwise it will trigger all systems associated with the ABS.

 

Now as you have a DSC light on as well this makes it a bit more complicated.

 

The DSC relies on a little black box mounted centrally in the car. The inertia of a skid is determined by the G force generated in unit and sends a signal to ABS unit.

 

These are just some thoughts with regards to progressing the problem but I can catagoricaly say it's not easy to trace these issues as they don't have access to what is known as live data.

[Nutgrove]

Thanks. Nothing's really changed with the wheels though. The rear tyres are newer than the fronts, but they were replaced over 6 months ago, and all are the same size.

I'm not sure what you mean by live data - is it driving with a laptop connected to the ECU so you can see what's going on? They have a fair amount of laptops and software but I'm not sure if they have the same degree as a BMW main dealer. I'll wait and see if this new unit solves the problem, and then will have some difficult issues to confront. If the problem is fixed, how many of the new parts fitted will I have to pay for? If it is not fixed, can I take the car away and pay nothing? If the answer to the second question is 'yes', are the garage responsible for getting the car repaired elsewhere?

[MegaCraggy]

you will have to pay the garage for the new parts fitted if everything gets resolved , it will also depend on what you agreed with the garage when you asked them to look at it.

if none of it has been resolved you will still have to pay for all parts they have fitted and take it to another garage to fix, they would be within their rights to keep your car until they get payment, if you pay , write clearly on the invoice "paid under protest", not just yours but also their copy too. this will be a record that you were unhappy with garage.

 

did they not inform you and ask you for your Authorization when replacing these parts ?

test drive the car before payment, as you state you are still unsure that the vibration is still there, have they informed you what parts that they replaced cured this?

As for the matter regarding the abs/dsc you might have some redress there about paying, because it seems this problem manifested when they were trying to cure the other problem , i would argue your case on this, and another thing you should ask for either way , is for all the old parts back.

[Nutgrove]

Thanks MegaCraggy. There was nothing wrong with the car when it went in to the garage. It was for a service, MOT, and front disc replacement which was part of the service - these are consumable items these days I believe? I would be more than happy to get the car back exactly as it went in! If only I could turn back time.....

[heliosuk]

Can you ask them to clear down the chassis system control module, test to get lights on again and let you know the fault codes that are being registered. Then post them here or let us know and I'll have a look. Remember the codes just because registered does not mean that part is faulty.

[LancerQRL]

a trick on a bmw to turn off the abs and dsc lights is to turn the steering lock to lock a couple of times then drive about half a mile, worth a try.

[Nutgrove]

Thanks very much - I'll try all of the above and report back!

[heliosuk]

Can't remember exactly but the speedo sensor on beemers is on the diff I think which is another signal the DSC picks up on. ABS uses the wheel speed sensors.

 

I wonder if they have jacked up the car on one end and the yaw sensor has got stuck????

[Nutgrove]

The fault code that is coming up is 'Brake pressure implausibility'. Not sure what that means though.

[heliosuk]

Need the code nutgrove. It will usually start with a letter followed by 4 numbers and for the code above there will have to be others as well so if you could get all codes it would help. It's also possible to be a 2 digit code but think this would be unlikely.

[Nutgrove]

Sorry for the delay, and I don't have the actual code. It is to do with the pressure from the charge pump when the self test runs at 20 mph. The pressure is low, and so the lights all come up on the dash - ABS, DSC, and also the '!' warning triangle. The garage have reached the end of their time with it as it is now 3 months, and although they are not charging for the 100 or so hours labour, I have a bill for about £3000 for parts which they have fitted which have not solved the problem. The list of parts is extensive, and would be a large bill even if it was fixed. A broken car and £3000 out of pocket is not good, especially as it would only be worth about £4500 in perfect working order.

[heliosuk]

I'll see what I can do with this. Can you ask them how they know the pressurre was low? Are they relying on the electronics or did they have an actual pressure reading?

 

It still suggests to me a Bleeding of fluid problem believe it or not.

[Nutgrove]

Hi, thanks for your help. They have replaced the pressure sensor twice in the abs valve block, but are getting error 5C which is low charge pump pressure or pressure 'out of acceptable parameters' I think. They have bled the system many times now and used gallons of brake fluid and they have done this using the computer (opening the nipples and pressing a button on the computer I believe).

[Nutgrove]

Actually I just went to the garage for all the codes, and this is a print out from one program which was done by someone they called in:

 

5C DSC: Pressure-sensor test

DSC actively switched

no ABS control

Stop-light switch: not actuated

no ASC control

no DSC contol

Brake booster: passive

no ACC control

no HDC control

 

 

The Win Star machine which is owned by the garage came up with these errors:

88 - Pre-charge pump

92 - Brake pressure sensor plausibility

 

If anyone has any further ideas I'd be most grateful!

[heliosuk]

Hi Nuts,

 

Sorry for the pun as I expect it is driving you so.

 

I have come across this before and it is extreamly rare but can happen. I'm not able to tell you where but is fixable if it is what I think and the history of the repair will sort of verify it.

 

If youd be kind enough to pm me with a breakdown/precis of what happened and the history of the garage diagnosis I'll run it by my guys to confirm or discuss what is the likely cause and suggest a way of getting over it. I could also do with knowing if the pedal feels hard or sinks i.e. irrespective of the lights, does the pedal feel normal. A way of doing this and gauging the degree of degredation is, if possible, to pump the pedal some 20 times, then run the engine for a few minutes. Turn off and repeat the pumping. Pedal should go hard after about 6 to 10 pumps. This exhausts the servo assistance and gives a real life condition of the hydraulic system.

 

To be fair, if it is what I think it is then it's highly unlikely they will have come across it.

[Nutgrove]

Hi all,

 

It went to a BMW specialist who managed to diagnose a faulty master cylinder and fix it within 2 days. I have been presented with a bill for £2500 (which includes the service and the disc and pad change - originally quoted at £1200). The question really is if this is fair to charge the extra £1300 especially as it has taken over 3 months. The charge pump is what was causing the problem originally, so I obviously don't mind paying for that.