Submariner1
Senior Member
- Joined
- Sep 3, 2016
- Messages
- 4,692
- Reaction score
- 788
- Location
- Windsor Berkshire
- Your Mercedes
- CL500 2009 5.5
I am intrigued to know, how do they train MB engineers in diagnosis?
I completely understand one cant just run a diagnostic tool on the car and just replace the items that have associated fault codes. Cheaper to buy a new car lol
IMO it just helps identify the general suspect components. But some may fail because others higher up the sequence failed.
I get that logic.
What I am intrigued with is when it finds suspect items, is this just because they are just lower down the chain of faults or is it indicative that they are only marginally within spec.?
Or is there absolutely no problem with these items, its just that there is insufficient voltage or current for them to operate correctly?.
A good example to explain my query is when my battery goes low voltage, it produces the “ABS and ESP are currently unavailable - See Owners Manual” dashboard message.
.. and the Manual says Unable to completed the initial self check diagnostics. (I assume due to low voltage? ).
I also see a differentiation between “currently unavilable” and the “inoperative or visit workshop” the latter I assume means a unit is defective, or potentially dangerous.
The MBII then finds the following faults
A) if the battery is slightly low
- low voltage on x sensor, reccommended visual inspection on the
- rear right and left rear RPM sensors and the front left sensor.
( I have cleaned the front sensors and reluctor rings ... all were reasonably clean and cleaned up nicely, and the rear right reluctor ring is new, courtesy of a new wheel bearing and hub ... non related issue).
B) if the battery is more discharged in addition to the above I get these fails:-
- right door controller open circuit or short to additional locks ( it doesnt have this option)
C if very discharged in addition to all the above, i get :-
- left seat lumbar motor
- no CAN message from N/?? ( ABS control unit )
If you drive 10 feet the message dissapears, and one can clear the codes.
If you fully charge the battery on the CTEK you never get this message or any fault codes. Leave the car 2 days and you can get the message, and it clears and one can start the car again that same day with no message or fault codes.
Leave it 3 days and the car will start and the message clears, but will reappear and be self cleared the next time you start it.
Initially I suspected a current drain, its at 40 to 50 mAs , which Mobilo says is fine. I did notice that when the battery is very low, the Fluke when set on Max Min ( time monitoring ) can see 110mA at some time.
Visually I saw this twice, and it will spike for 4 or five mins and drop back to 50mAs.
This NEW MB battery is also odd, in that when low normally takes 10-12 hours to go into “care” mode, but sometimes only takes 4 hours. Likewise it seems to have no guts! Sorry I really do not understand battery terminology. By that I mean if it shows 12.6V just open the door and the voltage crashes to 12.3V purely due to a door sam Using 350mAs . Is that normal?
I am sure impatient readers will say say for heavens sake just change the battery ... er I just did that, and got a faulty battery: and then got another new replacement. Note the DOA battery passed the full MB battery test 2 x and only failed on the 3rd battery test. This one is now showing the same attributes. Hence my fear of paying for multiple battery tests.
The normal process would be to have the battery tested, note that costs more than the actual battery.
TBH to solve this ****ing irritating problem, I would even pay that, if I thought it would get to the truth of the matter.
I strongly suspect this battery is defective and came from a faulty batch. ( same month of mfg.! )
Ironically I have decided to let the battery drain down and when it fails to start, call Mobilo and get it replaced. And then if the problem persists, give it to an Indy.
But I was again thwarted by this dam battery. Last night all shut down, drain of 40 - 30mAs it was 12.5V. This morning its up at 12.7V! The thing is posssessed. Makes me feel some of the cells are intermittantly not connecting properly. Is that possible. (note the first new battery finally failed when 2 out of the 6 cells went short circuit?? ... imo could that explain why sometimes she goes into CTEK care mode so quickly).
Am I right in waiting till she fails to start and getting a replacement battery before spending money on looking for a fault? ( note the first battery caused the very same modules to fail ).
Sorry if this irritates some folks but I really dont want to spend yet another £156 replacing another new battery.
Just to rule out water damaged SAMs and wiring, I had the body shop lift out the front carpets including removing throttle level, and look under the dash, check blower motor was totally dry, check all the drains incl. sunroof etc. ( all OK) and in their opinion the car has never got wet inside, there was no water staining etc, just some light dust. Local MB body shop did that for £40 ... very reasonable indeed.
The only thing I havent done is strip out the old tracker, its in the rear wing ... passenger cabin side so a total pig to get at. Rear window door card .. not fun on a Coupe. Tracker say this can for a short time send a comms msg. Using 300 to 500 mAs or the normal 1 to 3 mAs.
Imam now considering this ... as its an element the Indy cant test .. no fuse to pull.
Leads back to my main question, when one is tryi g to irradicate an intermittant current drain ( say there is one?? ) where the hell do you start if you cant see a drain?
Pull a fuse and leave it 3 days to rule it out! Christ that could cost a fortune?
Or is STAR clever enough to monitor the car for 24 hours and specify any current drains and where they were?
Alternatively can one just leave it, I assume that won't do any harm? And wait till something breaks, then at least you have something to find/mend!
Note for the cynical.
It took my wife to remnd me if out problems with an A Class battery. Replaced it and then it kept failing to starts. Numerous battery tests on the new battery. £460 of diagnostic tests and they removed my specialist Satellite tracker as that was deemed the only logical failure point. 3 days later she failed to start. Totally ****ed off I bought another new bigger battery. Its run perfectly for 4 years!
Luckily the garage refunded my £460 ... without me asking ... good customer service.
So bearing that in mind ... I trust the intelligent ones, can understand my relectance to accept “its not possible to get 2 defective batteries on the the trot”.
Ergo, did I really suddenly get 3 failing level sensors, an faulty ABS control module, a fauLty Door Sam and a faulty CAN controller and a faulty seat INSTANTLY ALL AT ONCE .?
I completely understand one cant just run a diagnostic tool on the car and just replace the items that have associated fault codes. Cheaper to buy a new car lol
IMO it just helps identify the general suspect components. But some may fail because others higher up the sequence failed.
I get that logic.
What I am intrigued with is when it finds suspect items, is this just because they are just lower down the chain of faults or is it indicative that they are only marginally within spec.?
Or is there absolutely no problem with these items, its just that there is insufficient voltage or current for them to operate correctly?.
A good example to explain my query is when my battery goes low voltage, it produces the “ABS and ESP are currently unavailable - See Owners Manual” dashboard message.
.. and the Manual says Unable to completed the initial self check diagnostics. (I assume due to low voltage? ).
I also see a differentiation between “currently unavilable” and the “inoperative or visit workshop” the latter I assume means a unit is defective, or potentially dangerous.
The MBII then finds the following faults
A) if the battery is slightly low
- low voltage on x sensor, reccommended visual inspection on the
- rear right and left rear RPM sensors and the front left sensor.
( I have cleaned the front sensors and reluctor rings ... all were reasonably clean and cleaned up nicely, and the rear right reluctor ring is new, courtesy of a new wheel bearing and hub ... non related issue).
B) if the battery is more discharged in addition to the above I get these fails:-
- right door controller open circuit or short to additional locks ( it doesnt have this option)
C if very discharged in addition to all the above, i get :-
- left seat lumbar motor
- no CAN message from N/?? ( ABS control unit )
If you drive 10 feet the message dissapears, and one can clear the codes.
If you fully charge the battery on the CTEK you never get this message or any fault codes. Leave the car 2 days and you can get the message, and it clears and one can start the car again that same day with no message or fault codes.
Leave it 3 days and the car will start and the message clears, but will reappear and be self cleared the next time you start it.
Initially I suspected a current drain, its at 40 to 50 mAs , which Mobilo says is fine. I did notice that when the battery is very low, the Fluke when set on Max Min ( time monitoring ) can see 110mA at some time.
Visually I saw this twice, and it will spike for 4 or five mins and drop back to 50mAs.
This NEW MB battery is also odd, in that when low normally takes 10-12 hours to go into “care” mode, but sometimes only takes 4 hours. Likewise it seems to have no guts! Sorry I really do not understand battery terminology. By that I mean if it shows 12.6V just open the door and the voltage crashes to 12.3V purely due to a door sam Using 350mAs . Is that normal?
I am sure impatient readers will say say for heavens sake just change the battery ... er I just did that, and got a faulty battery: and then got another new replacement. Note the DOA battery passed the full MB battery test 2 x and only failed on the 3rd battery test. This one is now showing the same attributes. Hence my fear of paying for multiple battery tests.
The normal process would be to have the battery tested, note that costs more than the actual battery.
TBH to solve this ****ing irritating problem, I would even pay that, if I thought it would get to the truth of the matter.
I strongly suspect this battery is defective and came from a faulty batch. ( same month of mfg.! )
Ironically I have decided to let the battery drain down and when it fails to start, call Mobilo and get it replaced. And then if the problem persists, give it to an Indy.
But I was again thwarted by this dam battery. Last night all shut down, drain of 40 - 30mAs it was 12.5V. This morning its up at 12.7V! The thing is posssessed. Makes me feel some of the cells are intermittantly not connecting properly. Is that possible. (note the first new battery finally failed when 2 out of the 6 cells went short circuit?? ... imo could that explain why sometimes she goes into CTEK care mode so quickly).
Am I right in waiting till she fails to start and getting a replacement battery before spending money on looking for a fault? ( note the first battery caused the very same modules to fail ).
Sorry if this irritates some folks but I really dont want to spend yet another £156 replacing another new battery.
Just to rule out water damaged SAMs and wiring, I had the body shop lift out the front carpets including removing throttle level, and look under the dash, check blower motor was totally dry, check all the drains incl. sunroof etc. ( all OK) and in their opinion the car has never got wet inside, there was no water staining etc, just some light dust. Local MB body shop did that for £40 ... very reasonable indeed.
The only thing I havent done is strip out the old tracker, its in the rear wing ... passenger cabin side so a total pig to get at. Rear window door card .. not fun on a Coupe. Tracker say this can for a short time send a comms msg. Using 300 to 500 mAs or the normal 1 to 3 mAs.
Imam now considering this ... as its an element the Indy cant test .. no fuse to pull.
Leads back to my main question, when one is tryi g to irradicate an intermittant current drain ( say there is one?? ) where the hell do you start if you cant see a drain?
Pull a fuse and leave it 3 days to rule it out! Christ that could cost a fortune?
Or is STAR clever enough to monitor the car for 24 hours and specify any current drains and where they were?
Alternatively can one just leave it, I assume that won't do any harm? And wait till something breaks, then at least you have something to find/mend!
Note for the cynical.
It took my wife to remnd me if out problems with an A Class battery. Replaced it and then it kept failing to starts. Numerous battery tests on the new battery. £460 of diagnostic tests and they removed my specialist Satellite tracker as that was deemed the only logical failure point. 3 days later she failed to start. Totally ****ed off I bought another new bigger battery. Its run perfectly for 4 years!
Luckily the garage refunded my £460 ... without me asking ... good customer service.
So bearing that in mind ... I trust the intelligent ones, can understand my relectance to accept “its not possible to get 2 defective batteries on the the trot”.
Ergo, did I really suddenly get 3 failing level sensors, an faulty ABS control module, a fauLty Door Sam and a faulty CAN controller and a faulty seat INSTANTLY ALL AT ONCE .?
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