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1999 SLK 230 Kompressor
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Discussion Starter #1
Hello All,

Recently purchased a 1990 SLK 230 Kompressor which I adore. It has a few, er, issues, that I'll gradually work through as I think it deserves it. Car is in good overall condition with 100k miles.

Now, having read all the previous threads here on BAS/ASR lights I thought I'd share my story and request for help, ideas, suggestions etc.

Since I have had the car the BAS/ASR light comes on whenever I initially first press the brake pedal to shift out of Park. What is odd is that it will not light until that first press, but then stays on continually even if I don't move at all.

When I got the car I took it to MB for a full service and to put a couple of things right. Now, £2200 later the light is still on. The dealership initially said "Oh yes, that'll be the brake light switch, then". It wasn't. They then said, "give us £50 to read the diagnostics and it'll tell us what the problem is". I did and it didn't. They charged me a further £250 and kept the car for nearly two weeks then announced it needs a new BAS/ASR control unit for a "greatly reduced" £1000. Gulp.

So, like I said, having read all the previous posts (by the way, why do some not call it BAS/ASR, its the light called something different BAS/ESP?? in other markets??). I am at a loss to give £1000 for a new controller when I frankly doubt it will solve the problem.

Do you believe either re-cleaning all the sensors and associated ephemera might clear it up? Also, I ought to mention the cruise control. It works intermittently, i.e. some days it works, others not, the while the light still glows...

Any ideas as to what else I can clean, test, eliminate before I have to cough for the £1000. Oh, that's another question. Can I buy a controller from somewhere else as it's only three connectors to plug it in?

Bazzle, any ideas, mate?

All help most gratefully received and copious amounts of free beer to anyone who can help me nail the problem.

Cheers, all.

Michael.
 

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2006 SLK 350
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620 Posts
Not bad, 100k miles on an almost 20 year old SLK. LOL!!!

This is the main reason I decided to give up on going to the dealers for anything that I could even remotely do myself or have an independent shop take care of (usually for much less.

These people are merciless!

I would definitely take it to a trusted indy and see if they can sort out the problem. Additionally, I would check around and see if that part can be purchased for much less (you just may be surprised).

Don't do like I did. I got scammed for years on the MAF and other issues to the tune of thousands and thousands of dollars before I got wise, came to this website and learned how to do certain things for myself.

Now, I perform all the A and B services, myself, as well as any other repairs or maintenance I can do, and the dealer hasn't seen me in over two years (and, presumably, thousands of "ohh look what we found" dollars).

Screw 'em!
 

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1999 SLK 230 Kompressor
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11 Posts
Discussion Starter #3
oops, fat fingered that one!

Well spotted.... Obviously I meant 1999.... now, where are my glasses..

While we are on the subject, anyone know of a good independent specialist in the Midlands here in England? I live just outside Leicester.

Will certainly be doing the servicing etc. myself in future, just wanted MB to have it to put it back to their standards, if you see what I mean?

And a source for reasonably prices spares in the UK would be good, too. Don't want the world, do I!

Cheers, all.
 

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2001 SLK230 SPORT
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23 Posts
since it doesnt go on until you press the brakes, i would guess it has to be related to the brake switch, is it possible that they put a faulty switch in? when i had your problem, it was a sensor in the console, the sensor was $100 and $100 to install it.
 

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SLK170 2003
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34 Posts
I had the BAS/ASR come on and off once. It was traced to the brake lights contact. Check that there is no chip/scratches on the spot where the brake light connector is secured.
If there is, a light sanding to the exposed metal section, apply flux and then solder to cover the scratch to give a good contact.
Hope this will be of help.

Cheers
 

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1999 SLK 230 Kompressor
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11 Posts
Discussion Starter #6
I'll re-check all the contacts in the brake circuit, and see if I can take apart/check/clean the brake light switch.

Chevitz, which sensor are you refering to? I can't find a sensor in the console or a reference to it, maybe it's missing from my car??

David, are you refering to where the brake light wires attach to the brake light switch at the pedal end?
 

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96 Posts
On my 2000 SLK 230, I too had problems with the light coming on; again only after pushing the brake pedal.
Another difficulty is that when the light is on, the cruise controll doesn't work.

I bought the "brake pedal switch" for only ~$15, but it was a little difficult to change with so little room up under dash. I guess I am just too big. My smaller friend said he had changed one in 30 seconds.

After changing the switch, STILL the light came on after brake pedal application.

I finally solved the problem a year later.
When I first got the car I had changed wheels and tires to AMG 17 inch with YOKO ES100 235/40 X17 front and 245/40 X17 rear. They are about 6/10 of inch similar diameter. I had to replace both fronts and kept the slightly worn backs.(so slightly smaller diameter than originally). Now with the "bigger/ same" diameter fronts to the rears, the light does not go on.
This tells me that:
1. I didn't need the brake pedal switch.
2. The system is REALLY SENSITIVE to all 4 tire diameters being very close.

Mark
 

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SLK170 2003
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34 Posts
Mark,

The brake light bulb holder contact against the tail light metal part. The chip/scratch can be a small area and hence the contact between the bulb holder and the metal is poor. The BAS/ASR light will come on and off depending on the contact. When the car is in motion or there is vibration when the engine is started, poor contact will trigger the BAS/ASR light.
This problem with the brake light contact was also brought out by one of the member sometime ago.

Cheers
 

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1999 SLK 230 Kompressor
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11 Posts
Discussion Starter #9
David,

I took out both rear cluster and yes, there was pitting and corrosion in all the tracks. Made good all the connections, filled the holes with solder and put them back but the problem is still there.

Now, ***** UPDATE ***** what happens is this. Start car, BAS/ASR light is off. Press brake pedal, brake lights come on BAS/ASR light is off UNTIL you press a bit harder, enough to pressurise the fluid in the system, THEN the BAS/ASR light comes on.

So, it would appear the brake light circuit is working ok and the BAS/ASR light only comes on when there is some pressure in the brake circuits. So, is there some sort of sensor or switch or something that might be causing the problem? I've tried looking in the manual I got from the web on 2 x DVDs, apparently the MB manual, but drawn a blank.

Anyone any more ideas??????

Cheers, all.

Mick.
 

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1999 SLK 230 Kompressor
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11 Posts
Discussion Starter #10
Tyres and Wheels

Mark,

I have the factory standard wheels and tyres on mine so hope that it isn't causing the problem!

When you fixed your problem, did you try putting the others back on to see what happened? Also, does your light come on with tyre wear? I'm just really curious as to how sensitive this thing is?

Cheers,

Mick.
 

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Are you aware of the factory recall on the taillight assemblies?
Last year, mine were replaced for free at the dealer even though I am the second owner and I had ~100,000 miles on the car.

My taillight assemblies were pitted at the socket with a sporatic brake light on one side.
New assembles did not fix the BAS/ ASR light. But the new tires on front with the slightly worn on rear DID fix the problem.

I MAY have had 2 problems before the taillight assembly change:
1. the assemblies
2. the tire diameter differential.

Even though you can fix with solder, why not get brand new ones for free?

So I haven't tried putting the old original 16 inch tires and wheels back on (YOKO ES100 225/45 X 16 ZR). Besides, they are in use on my daughter's 190E 2.6. They look just OK on the SLK 230, but they really improve the looks of the 190E. It also handles much better now.

Mark
 

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1999 SLK 230 Kompressor
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11 Posts
Discussion Starter #12
wasn't aware of the recall on the tail-lights. I'll look into that.

As to the problem, I am startingto think it may be only when the brake system has some pressure in it as it (the light) only comes on when you press hard enough to actually use the brakes and not just light the brake lights.

I'm trying to find a wiring diagram for the whole brake BAS/ASR circuits but nowt so far.
 

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Two 1998 SLK230s, 2003 SLK230 SE, 2002 ML320
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920 Posts
A few points
- the faulty brake light assembly recall was in the USA only. The rest of us have to effect our own repairs. I did but in the end replaced them with the better looking and brighter LED assemblies.
- The brake light problem has nothing to do with the BAS light coming on
- Earlier SLKs has ASR and post facelift (2001 I think) have ESP.

I think you're on the right track thinking about hydaulic brake pressure. Have you checked the brake fluid levels and also for any leaks? You may not notice as there are two brake hydraulic circuits I believe.
 

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1999 SLK 230 Kompressor
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Discussion Starter #14
Brake fluid is spot on, no leaks either.

Wasn't aware of the recall being only USA, figures, but thanks anyway. I've repaired the various tracks and all work very well now but still the light comes on *AFTER* pressurising the system. Odd.

I'm now of the mind it is not merely a brake light circuit issue but am not too sure where to go next.

Anyone??
 

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Two 1998 SLK230s, 2003 SLK230 SE, 2002 ML320
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920 Posts
Did you get any diagnostic trouble codes from the car? These are helpful in isolating the problem. Use CarSoft or the MB dealer or an independent mechanic can pull them for you.
If you fill in your avatar on the left, it would be helpful to have your location and model of SLK.
Other causes reported for the BAS light staying on:
- excessive brake pedal travel (brakes not bled properly)
- low voltage (alternator or battery giving up the ghost)
- wheel sensor rings dirty - measure the revs at the wheels and if not matched the BAS light will come on
- tyre pressures out of spec leading to wheel speed differences
- tyres not the right size leading to outer circumference differences between wheels

Best next move is to get the diagnostic codes.
 

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SLK170 2003
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34 Posts
Mick

The other possibilities maybe :-

a faulty steering angle sensor,

The rear right speed sensor was defective.

Low battery (voltage measure, and replace if necessary

Central control unit is defective:-
Magnet Cam Adjuster (MCA) cable harness should have no trace of engine oil as the oil from the harness can contaminate the ECU and cause the warning lights to come on. From previous articles in this forum, this is an expensive repair I believe it is similiar to the controller you have mentioned in your first write-up.
Hence check that the MCA harness or connection plug do not have traces of engine oil.

Cheers

David
 

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1999 SLK 230 Kompressor
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Discussion Starter #17
David, thanks for all of the above. I've checked just about everything and all seems to be in order.

Now, I've just been out to test drive and have come up with some rather interesting and frankly puzzling new information.

To re-cap, start engine, no light. Apply brakes enough to light brake lights, no light. So, without pressing too hard on the brake pedal, off for a somewhat tentative test drive...

While driving and using the brakes *lightly* (I know, I know, should always be so... to appease all our advanced driving brethren) the brakes function normally and light stays off. Now, here is the REALLY interesting bit... whether in traffic or out on the open road, if the pedal is moved a long way, and it does seem to move a long way on my car, infact almost to the floor, on comes the light. Brakes still function normally albeit harsher with that amount of pedal travel. Switch off, restart, no light until next long push of pedal.

So, now I'm wondering does the BAS/ASR system monitor pedal travel somehow? Could it be that the system thinks there is a problem with the brakes as the pedal moves such a long way? In truth I have only just discovered this as previously I just used to press the pedal all the way, shift out of park and drive away, it is only since trying to nail this problem I've tried barely using the pedal. I did query the pedal travel with MB atlast service but was told "Our pedals do travel a long way, Sir".

Anyone know if there is a 'spec' for how far the pedal should travel before being unable to move further?

Far from being a mere annoyance this is now becoming quite interesting!

As usual, all help, suggestions, mickey taking PMs gratefully received.

Cheers, all.

Mick.
 

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1999 SLK 230 Kompressor
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11 Posts
Discussion Starter #18
OZTDS - see previous post re brake pedal travel as you mention in one of your earlier posts.

I had the fluid changed at the last service by MB and pedal travel has stayed the same. Do you know what is allowable by the BAS system? Will try to re-bleed all brakes but hope they did it properly!

Cheers,

Mick.
 

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Two 1998 SLK230s, 2003 SLK230 SE, 2002 ML320
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920 Posts
OZTDS - see previous post re brake pedal travel as you mention in one of your earlier posts.

I had the fluid changed at the last service by MB and pedal travel has stayed the same. Do you know what is allowable by the BAS system? Will try to re-bleed all brakes but hope they did it properly!

Cheers,

Mick.
Mick, I don't know off-hand what the spec is. I have had 3 SLKs and on all of them the brake pedal had very little movement.
Check that calipers and brake pads are properly seated and aligned and that you don't have air in the brake lines. Maybe a broken seal somewhere in the master cylinder or one of the slave cylinders - but you said no leaks evident.
There are some posts:
http://www.benzworld.org/forums/r170-slk-class/1246076-excessive-brake-pedal-travel.html
http://www.benzworld.org/forums/r170-slk-class/1175839-fluid-changes-needed-not.html
http://www.benzworld.org/forums/r170-slk-class/1285952-power-brake-booster-master-cylinder.html
 

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Two 1998 SLK230s, 2003 SLK230 SE, 2002 ML320
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920 Posts
David, thanks for all of the above. I've checked just about everything and all seems to be in order.

Now, I've just been out to test drive and have come up with some rather interesting and frankly puzzling new information.

To re-cap, start engine, no light. Apply brakes enough to light brake lights, no light. So, without pressing too hard on the brake pedal, off for a somewhat tentative test drive...

While driving and using the brakes *lightly* (I know, I know, should always be so... to appease all our advanced driving brethren) the brakes function normally and light stays off. Now, here is the REALLY interesting bit... whether in traffic or out on the open road, if the pedal is moved a long way, and it does seem to move a long way on my car, infact almost to the floor, on comes the light. Brakes still function normally albeit harsher with that amount of pedal travel. Switch off, restart, no light until next long push of pedal.

So, now I'm wondering does the BAS/ASR system monitor pedal travel somehow? Could it be that the system thinks there is a problem with the brakes as the pedal moves such a long way? In truth I have only just discovered this as previously I just used to press the pedal all the way, shift out of park and drive away, it is only since trying to nail this problem I've tried barely using the pedal. I did query the pedal travel with MB atlast service but was told "Our pedals do travel a long way, Sir".

Anyone know if there is a 'spec' for how far the pedal should travel before being unable to move further?

Far from being a mere annoyance this is now becoming quite interesting!

As usual, all help, suggestions, mickey taking PMs gratefully received.

Cheers, all.

Mick.
Something is seriously wrong if the brake pedal a) has different catch points and b) travels almost to the floor.
How can MB give you back a car that has that behaviour and charge you money for their service? I'd be making a warranty claim on the service - at least you may get a diagnosis.
The brakes should be effective with only a few cms of brake pedal travel.
I would venture to say the car is dangerous to drive in its current condition if as you describe. :eek:
 
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