W210 Cruise Control and BAS ASR promlem

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Oxfordjim

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The BAS ASR warning lamp came on when I pressed the brake peddle and has remained on since, then when on the motorway I noticed the cruise control no longer works, however the limiter does....on startup I get BAS and ASR alerts
I've checked all the fuses, any suggestions?
Thx
 

television

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Just change the brake lamp switch, it knocks the CAN speed signal in the BAS unit out, it is cheap and sits on the top of the brake pedal
 
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Oxfordjim

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Thx for quick reply...

Thx Television, I'll get a replacement switch, and let you know how I get on
Cheers :p
 
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Oxfordjim

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Forgot to mention...

My brake lights are still working, does this make a difference?
 

Alex Crow

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Just change the brake lamp switch, it knocks the CAN speed signal in the BAS unit out...

malcolm, i know you get a lot of requests for documents, but if you could forward me those 2x you mentioned before that detail the above i will be tremendously grateful. :D:D:D
 

television

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malcolm, i know you get a lot of requests for documents, but if you could forward me those 2x you mentioned before that detail the above i will be tremendously grateful. :D:D:D

Yes I will do that Alex,, I do know what you are saying but all ECU's that carry lines like the speed signal or something else have a de coupling circuit so that that signal cannot go down in the whole car, so in this case the speed signal is only lost within that BAS module and the rest of the car is not affected, like all complex electronic ECU this has to be the way, and more so when it comes to power circuits so that the whole thing does not crash.

So in the end the CAN signal is not correct and that is sent out to what ever part of the car needs that info, and this is where the CAN comes into the equation
 
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umblecumbuz

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Yes I will do that Alex,, I do know what you are saying but all ECU's that carry lines like the speed signal or something else have a de coupling circuit so that that signal cannot go down in the whole car, so in this case the speed signal is only lost within that BAS module and the rest of the car is not affected, like all complex electronic ECU this has to be the way, and more so when it comes to power circuits so that the whole thing does not crash

Well ... I'm improving. I understood some of those words!
Baz
 

television

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Well ... I'm improving. I understood some of those words!
Baz

It really a world on its own all this stuff, no car mechanic should be subject to it too deeply, it is very unfair what has taken a lifetime for me to be burdened on someone who is not into electronics. OK they have STAR that tells them what to do, and that is where it all ends
 

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Actually, the words I understood were: television, Alex, speed and crash!
Baz
 

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.........all ECU's that carry lines like the speed signal or something else have a de coupling circuit so that that signal cannot go down in the whole car, so in this case the speed signal is only lost within that BAS module and the rest of the car is not affected.........

thanks for the documents malcolm, much appreciated.

any chance of telling me where you read about the above^^^?
or an explanation of why you make the statement above?


i know what you mean about mechanics, as an engineer i am very busy doing work for other garages that have neither the knowledge or intellect to carry out successful diagnosis and repair - slaves to the instructions on WIS and STAR!
i estimate that over 1/3 of my work is for other garages, and the number of additional phone calls i get for help is overwhelming on occasion.

unless of course that was a veiled slur aimed at myself?
i do hope not.
 

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thanks for the documents malcolm, much appreciated.

any chance of telling me where you read about the above^^^?
or an explanation of why you make the statement above?


i know what you mean about mechanics, as an engineer i am very busy doing work for other garages that have neither the knowledge or intellect to carry out successful diagnosis and repair - slaves to the instructions on WIS and STAR!
i estimate that over 1/3 of my work is for other garages, and the number of additional phone calls i get for help is overwhelming on occasion.

unless of course that was a veiled slur aimed at myself?
i do hope not.

I know because that is how these things work, they have to, I could take say a speed signal for some electronic device that I was making up, but I would make sure that in the event of a burn up it did not take out the whole speed signal, for a little decoupling or buffer amp would pass the speed signal but not allow it to be killed.

If you take these BAS units and the codes here.

normally if there are no faults, then no codes, but the Brake switch malfunctioned and this interfered with the speed signal within the BAS unit, then the CAN could not send the correct signal that everything was OK when it was not, so the fault code C1025 is generated.

The component that wanted this info did not get an all clear message back so for safety it turned things off and put up the warning, all done via the EIS, the master controller.

All communication is done via the CAN, that is the idea of it. This BAS takes in so much info, so this has many in and out ports, all designed for the minimum interruption if one port goes down.

With electronics I cannot talk in car language, only the way I would discuss a problem with a like minded engineer, so I try and put up answer here in terms that are understood by most and my answer here and elsewhere is near enough I feel,, but is anyone really bothered, they are only interested in clearing the fault and replacing the switch.

I recall you questioning me about the statement I made re the CAN when you said that no can wires go to the brake lamp switch, well of coarse nothing at all on the car connects directly with the CAN circuits, the CAN is all outputs on these components with nothing else at all, in these cases the switch has not sent an all clear message to the BAS, and the CAN passes that information on in fault code terms.

Now Alex please do not think or infer that I would slate you in any way, to the contrary I think that you are one of the only mechanics around that has a good understanding of electronic circuits, and I take my hat off to you on these things.

I did start writing out some clear explanations to put up in a sticky or DIY, but to a fair extent it is not wanted owing to the very few that might understand it all
 

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I know because that is how these things work, they have to, I could take say a speed signal for some electronic device that I was making up, but I would make sure that in the event of a burn up it did not take out the whole speed signal, for a little decoupling or buffer amp would pass the speed signal but not allow it to be killed.

If you take these BAS units and the codes here.

normally if there are no faults, then no codes, but the Brake switch malfunctioned and this interfered with the speed signal within the BAS unit, then the CAN could not send the correct signal that everything was OK when it was not, so the fault code C1025 is generated.

The component that wanted this info did not get an all clear message back so for safety it turned things off and put up the warning, all done via the EIS, the master controller.

All communication is done via the CAN, that is the idea of it. This BAS takes in so much info, so this has many in and out ports, all designed for the minimum interruption if one port goes down.

With electronics I cannot talk in car language, only the way I would discuss a problem with a like minded engineer, so I try and put up answer here in terms that are understood by most and my answer here and elsewhere is near enough I feel,, but is anyone really bothered, they are only interested in clearing the fault and replacing the switch.

I recall you questioning me about the statement I made re the CAN when you said that no can wires go to the brake lamp switch, well of coarse nothing at all on the car connects directly with the CAN circuits, the CAN is all outputs on these components with nothing else at all, in these cases the switch has not sent an all clear message to the BAS, and the CAN passes that information on in fault code terms.

Now Alex please do not think or infer that I would slate you in any way, to the contrary I think that you are one of the only mechanics around that has a good understanding of electronic circuits, and I take my hat off to you on these things.

I did start writing out some clear explanations to put up in a sticky or DIY, but to a fair extent it is not wanted owing to the very few that might understand it all

malcolm, i have 2x things to say...

1. i do not agree with some of what you are saying - i note that you reasonably point out the possible missunderstandings with terms used etc.
i hope we can agree to disagree on our points of difference.

2. i am glowing from reading the bold text in your post - it would be appreciated from anyone, but means a great deal coming from you.


for all interested forum members, general reading on CAN BUS systems...

there is not yet a truly MB specific can capture and review system yet available, but it is coming! have a look here, free demo download very interesting... http://www.cancapture.com/cancapture.html

a good wikipedia page on bosch developed CAN function, protocols etc... http://en.wikipedia.org/wiki/Controller_area_network

and a slightly easier reading article with a case study on an MB car... http://www.asashop.org/autoinc/may2007/techtips.htm
 

television

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malcolm, i have 2x things to say...

1. i do not agree with some of what you are saying - i note that you reasonably point out the possible missunderstandings with terms used etc.
i hope we can agree to disagree on our points of difference.

2. i am glowing from reading the bold text in your post - it would be appreciated from anyone, but means a great deal coming from you.


for all interested forum members, general reading on CAN BUS systems...

there is not yet a truly MB specific can capture and review system yet available, but it is coming! have a look here, free demo download very interesting... http://www.cancapture.com/cancapture.html

a good wikipedia page on bosch developed CAN function, protocols etc... http://en.wikipedia.org/wiki/Controller_area_network

and a slightly easier reading article with a case study on an MB car... http://www.asashop.org/autoinc/may2007/techtips.htm

In your point 1 Alex, does it really matter, I read some of the links and I will not agree with some parts,it all depends on the school where you were taught, so you see it the way you have read about it, and I read it all my way. The other thing is there are many CAN bus systems and the one that MB use is not really like any other in several respects, so just reading about the voltages on the average car is meaning less on a MB and you could end up in deep water if you tried to find a CAN fault by the average link on the Web

Now short of getting hold of the micro design and component chart within a BAS ECU we can do no more, by this I do not mean the pin outs, other standard chips I have all the info that I need. So we have MB describing the fault one way,the links another, me another and you in your way.

It reminds me of when I had to lecture on how lasers worked around the UK, I was taught by Tascam, sitting in on a lecture in Sweden on the same subject with a lecturer from Yamaha he missed many important things out and I had to go up and fill in the missing parts.

With your point 2, then as I said I admire the fact that you want to know more than most, and do. With engineering one can see moving parts,check end floats and what ever as it can all be measured. In electronics nothing moves and nothing to see, sure we can test in more ways than one.
Life is not so easy for those in the field, as we have limited information, I like you always want to know why something failed, it must be boring to just change something because STAR said so. I have only ever got job satisfaction if I know that I have done a good job, you are the same :D:D
 

television

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... I give up!
Baz

Best way, life is boring now with all the fun of changing parts at component level gone for ever, you just need a credit card to replace the complete lump now days
 

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