ESP - BAS - ABS Locked in Park

[Lozzar]

So...

Having briefly scanned this thread, I would suggest you have missed, mainly because you probably arent able to, some basic diagnosis here.

Can you read the live data with your scanner? If so, you should be able to see the brake light switch function on/off. If that is the case, you could simply know that your switch, wiring and ABS controller are working perfectly without having to swap out sensors and modules.

Next can you read the ESM module with your scanner? If the answer is yes, can you look at live data? The live data on STAR has a value for brake light switch operation. Is the ESM seeing the brake light switch function? If the answer is yes, then comms from the ABS pump to ESM is ok. That confirms wiring, CAN and ABS module function and the fault is with your selector module.

The way I can be sure of all of that is because none of it would communicate without being able to talk to one another. Also, if you were using a half decent scanner, the CAN for the ABS runs off the chassis network, if you had a CAN issue, it would take out the whole network and report it as running in single wire mode affecting other modules along the way.

Throwing bits at it and swapping modules and pumps is a sure fire way to (a) costing you a shed load of time (b) money (c) a lot of frustration.

Diagnostic tools in the hands of the right people will save all of your messing around.

Thanks for this. I did purchase an "iCarsoft MB v1.0", from Diagnosticworld.com. I was assured this was the right scanner. Previous to that i borrowed a "Proffessional Scanner" from a friend in Sheffield. I was on a tight time frame not wanting to affect his business. The images from the top class scanner are at the beginning of the thread. I then purchased the iCarsoft MB1.0 scanner and both scanners identified the Brake switch as the fault. You're no doubt correct, the scanner is not in the best hands in me and I may not be using the scanner properly. I did do a "Live" scan, Its a while since I did the check so I'm struggling to remember the values. Using the borrowed scanner I was able to save images if the results (at the start of the thread) but the iCarsoft scanner saves reports to a format with suffix .rex and is not comparable to any app I have to view it away from the scanner. Diagnosticworld were supposed to be helping me with that. I'll run my scans again and take phone images of the live data and report data and see if I've missed something or look at the data in conjunction with you helpful comments above. Many thanks.

 

[Steve@Avantgarde]

Just because it flags a sensor as a fault, it doesnt mean thats the issue, or even thats the cause of your problem. It could be an affected component, just like your selector module not coming out of park is, so you it may mean you will be looking at what live data is missing. The reason for that is a 2002 model has very primitive electronics, not all modules or sensors have a fault capability. So sometimes faults on these cars can spin you in all sorts of directions.

Does the ESL unit come up and read on the icarsoft?

When I talk about live data, im talking about reading actual values from the vehicle. EG: If you go into the selector module, its live values will be able to tell you what gear position its in. It will be the same for sensors and modules, that live data is the what you need to study to fix your vehicle.

Of course, if you had a STAR machine, there is a guided test function that would lead you right to the fault. A lot of people swear by the capability of icarsoft. I've never used one personally as I have Xentry STAR being an indie, the next best non genuine machines I've used with very good live data reads are the Texa and Autel (excellent for a generic diag tool) systems which have live data and wiring diagram attachments.

I would be interested to see a complete fault code scan of all the cars systems first. I think you need to go back to the begining and forget everything you have checked, tested or replaced. Oh and never assume anything...always replace on what you can test and prove to be faulty.

 

[Lozzar]

A Small Break Through: Hi Guys, apologies for a time lapse. I employed 2 Local, Mobile Diagnostic Engineers in the last two weeks (remember the car is immobile, locked in Park). The first guy ended up with the same diagnosis as my £100 iCarsoft MB v1.0 machine (www.Diagnostic-world.com), the "Brake Switch reading Implausible". Did lots of tests, fuses, connectivity etc. Eventually we passed the issue to another engineer with the superior "Star" machine however from a purely diagnostic stand point we got no further. There's a realisation that it has to be something to do with the wiring linked to the Brake Switch and not the Switch itself. I showed him the 2nd hand ABS SAM Aluminium case unit I had. This resides in the passenger side fuse box (RH Drive car). We swapped it and got the same result, the Brake light permanently on. But this time, Mel, the Diagnostic guy, had the experience and confidence to pull out all the SAM units from this fuse box to examine them underneath and look at as much wiring as possible. During this process Mel pulled and tugged on the various wire harnesses and the Brake Light Flickered!
It wasn't clear at first why this was happening but when he was putting these units back into the plastic Fuse Box that we had a breakthrough! The Aluminium ABS SAM unit touched a Bolt holding the fuse box in place. There were small sparks! The sparks coincided with the brake light going off and on. Sadly we couldn't find a position where the the brake light stayed off. However this told Mel that we must have a Bad Earth somewhere. Finding Bad Earth connections is not Mel's speciality. He does have a friend who works for Benz. His friend has had cases like this and it can sometimes be a Relay fault. We are checking which Relay(s) is linked to the Brake switch and hopefully make more progress. We have made progress but not fully fixed yet. Costs so far not too bad!! compared to some of the stories I've read. Regards.

 

[mattkh]

Thanks.
Whereabouts in the car is this fusebox..?
As a guess there are about five earthing points on a car.
What you are naming Aluminium ABS SAM unit, is it the one connected to the ABS pump or something else.

 

[Lozzar]

Thanks.
Whereabouts in the car is this fusebox..?
As a guess there are about five earthing points on a car.
What you are naming Aluminium ABS SAM unit, is it the one connected to the ABS pump or something else.

Hello again Mattkh, thank you for continued interest. Your question is best answered with graphics: Hope they are clear enough. The Securing Bolt secures the outer plastic box where the module and many fuses and relays are housed. Under the Bonnet on the Passenger side (RH Drive Car) up against the bulkhead, an area potentially susceptible to water draining off the windscreen although in my case it looks quite dry, a few leaves maybe. Regards.

 

[mattkh]

Thanks very much for the graphics. Briliant.

 

[Lozzar]

Thanks very much for the graphics. Briliant.

No problem. The ABS module in the photo, I have 2 of these now. I bought a replacement one off Ebay thinking that was the problem. It was cheap enough to take that punt. As it happens the fault is exactly the same with either module. When I get this fault fixed I will stress test the purchased module and make sure it is a good working module and at that stage I will be happy to sell it on for the same £50 I paid for it. So if anyone diagnoses that they need this module I'll be welcome to pass it on for £50. Regards.

 

[mattkh]

A humble request whenever you can do it.
A photo please. The so called brake servo, a saucepan shaped that sits below the brake fluid bottle.
If you can see any electrical connector going to the saucepan area (not the one to the bottle), I would love to see a photo of that showing the wires and the colors. Thanks.

 

[Lozzar]

A humble request whenever you can do it.
A photo please. The so called brake servo, a saucepan shaped that sits below the brake fluid bottle.
If you can see any electrical connector going to the saucepan area (not the one to the bottle), I would love to see a photo of that showing the wires and the colors. Thanks.

I will do that this afternoon. It's something I want to investigate anyway. The Sensor there is called the the "Brake Pressure" sensor and this can be a source of the fault I have even though all the diagnostic tools suggest the "Brake Switch" sensor is the fault using that non-descript phrase "Implausible". Common sense would suggest the two must be linked, at least through the CAN Bus if not directly. Regards.

 

[Lozzar]

I will do that this afternoon. It's something I want to investigate anyway. The Sensor there is called the the "Brake Pressure" sensor and this can be a source of the fault I have even though all the diagnostic tools suggest the "Brake Switch" sensor is the fault using that non-descript phrase "Implausible". Common sense would suggest the two must be linked, at least through the CAN Bus if not directly. Regards.

See pictures of the Brake Servo Pressure Sensors. Couldn't work out how to remove them. Does anyone know if they are Integral to the "Servo"?? (or Brake Booster as it is described in US videos). Can they be removed and replaced??

 

[mattkh]

Thank you for the photos. I looked at pictures of the brake servos on ebay. From what I can see the sensors seem to be integral .
Am I right in thinking that the MBenz standard color is BROWN for EARTH,
If so, then you can check the resistance from the brown wire (with the ignition OFF) on the two plugs of the servo, to the negative terminal of the battery.
It should be close to zero.

 

[Submariner1]

It certainly won't help m8. Best get it charged up to around 12.4v at least.

Totally agree.
Changed battery on my CL500 more as a precaution cos it kept running low low at 12.4 V if left a day. Alternator showed 14.4? Ish.

Got a dud new one ( since replace FOC by Mobilo - so defo a defective one ).
well when the new one dipped to 11.9V -12.1V .... the list of fault codes went through the roof!
Mobilo put in a new battery showing 12.8V
- a bit disconcerted by getiing a duff genuine new MB battery ... I asked to see the replacement ones voltage.
He cleared All the fault codes, and bingo. Zero fault codes .

Being sceptical, offered him a coffee and he re-ran the code reader. Zero faults.
All has been fine since and checked periodically with an icarsoft MB2, always zero faults.

Only exception was when I lost a front wheel sensor, then got a few abs type fault codes. Replaced one all fine, 2 months later blow me the other one went! Car had done 45,000 but it is an 09.

He said it normal, these CLs really hate low voltages, and fault all over the place, when there is no real fault?

just my experience ... always make sure your voltage is good to excellent, before proceeding.

 

[Lozzar]

Thanks for all that. For most of this diagnosis the battery has been around 12.4/12.8. Cranks and starts the engine when required. Ive checked ALL the Relays in all the fuse boxes where the Sam units are located. I've ordered a rear Sam. The second Diagnostic guy sought advice from a London based MB employee. The faults make him think it is the Rear Sam unit. I Should get it tomorrow. Its a bit of a Punt but I think worth it. I'll post the results when I've fit the replacement Rear Sam. Cheers All.