SBC Tech Question - Root Cause
11-21-2015, 06:31 AM
#1
Junior Member
Thread Starter
SBC Tech Question - Root Cause
Hi all, just want to know does anyone know exactingly what is failing (or wearing out) in the SBC module that gives it a limited number or pedal applications? Motor, high pressure pump, solenoids, accumulator etc?
If this has been covered on another thread can some please direct me?
The company I worked for had looked at a few SBC modules years ago when the problem just surfaced and done counter resets with DAS. Then it was found that was a bad idea (anamaniacs sketches come to mind) and we stopped doing resets so any enquirers about that system led to "head to the dealer".
Never got the chance to do any investigation as to why it was failing. From memory there was vague information that the pressure sensor would fail with age. Strain gauge pressure sensor are usualy quite reliable so I think that is rubish.
Cheers.
If this has been covered on another thread can some please direct me?
The company I worked for had looked at a few SBC modules years ago when the problem just surfaced and done counter resets with DAS. Then it was found that was a bad idea (anamaniacs sketches come to mind) and we stopped doing resets so any enquirers about that system led to "head to the dealer".
Never got the chance to do any investigation as to why it was failing. From memory there was vague information that the pressure sensor would fail with age. Strain gauge pressure sensor are usualy quite reliable so I think that is rubish.
Cheers.
11-21-2015, 11:32 AM
#2
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1922 Ford Model T / no OBD
When we might never learn what failed on those few reported incidents, in each electric motor the first thing to wear out are brushes.
I keep advising for years that on car with 100+k miles replacing alternator brushes should be on top of maintenance list, yet year after year we have owners coming with question "What that red battery warning means?"
No wonder MB made idiot light on brake pump that comes before failure.
I keep advising for years that on car with 100+k miles replacing alternator brushes should be on top of maintenance list, yet year after year we have owners coming with question "What that red battery warning means?"
No wonder MB made idiot light on brake pump that comes before failure.
Last edited by kajtek1; 11-21-2015 at 11:59 AM.
11-21-2015, 12:42 PM
#3
Member
Brushes may be one reason why running threshold is set in system, there is one case in Finnnish MB forum where member actually checked brushes after counter was full, and there was plenty of them left. Of course there should be some safety marigin and that case was only one, no statistical relevance.
11-21-2015, 06:27 PM
#4
Junior Member
Thread Starter
Brushes, That's a good point. It may be that in severe cases (total lost of braking) the brushes wear out and the nitrogen filled accumulator loses gas resulting in a total lost of any sort of assist - mechanical pedal only.
I now remember a similar situation on the Mitsubishi Pajero Excede where the accumulator lost gas so the pump would operate on every pedal actuation instead of every 8th or 10th. That destroyed the high pressure pump motor so you get very little brake assist on a very heavy 4WD.
Just regarding alternator brushes comment. Whats that, preventative maintenance? Dont you normally wait until smoke pores out or wheels fly off then ***** and moan about the cost of repair.
I now remember a similar situation on the Mitsubishi Pajero Excede where the accumulator lost gas so the pump would operate on every pedal actuation instead of every 8th or 10th. That destroyed the high pressure pump motor so you get very little brake assist on a very heavy 4WD.
Just regarding alternator brushes comment. Whats that, preventative maintenance? Dont you normally wait until smoke pores out or wheels fly off then ***** and moan about the cost of repair.
11-21-2015, 06:31 PM
#5
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1922 Ford Model T / no OBD
Safety margin is a thing that can surprise some.
For example elevators have cables design with safety factor 5.
Meaning that on elevator of 1000lb capacity the cables will hold 5000lb just fine.
That beside dual emergency brakes on each elevator.
I would not be surprized that SBC goes to the junk with 50% or remaining brushes.
That would make "only" safety factor 2.
Obviously brushes are the easiest thing to measure. The hydraulic pumps wear out as well, but that is harder to measure.
Another direct compare is airmatic compressor.
It does not have counter and lot of cars come to dealership on flatbed becouse of its failure.
So think about it.... flatbed with compressor or alternator failure and what in case of SBC failure?
For example elevators have cables design with safety factor 5.
Meaning that on elevator of 1000lb capacity the cables will hold 5000lb just fine.
That beside dual emergency brakes on each elevator.
I would not be surprized that SBC goes to the junk with 50% or remaining brushes.
That would make "only" safety factor 2.
Obviously brushes are the easiest thing to measure. The hydraulic pumps wear out as well, but that is harder to measure.
Another direct compare is airmatic compressor.
It does not have counter and lot of cars come to dealership on flatbed becouse of its failure.
So think about it.... flatbed with compressor or alternator failure and what in case of SBC failure?
11-23-2015, 09:14 AM
#6
MBWorld Fanatic!
actually there are time/frequency counters built into both of these units, airmatic compressor has a operating time that should be reset after replacement, not aware of a specified value of spec of operating time is but i would assume it is drastic. You need DAS for that to reset operating time. Sbc gives you a warning when it too will need to be replaced-threshold met-software update required. Your soft ware update is your verbal and visual warning. But if you don't take your sbc powered vehicle to a dealer you wouldn't know that.
So in theory a heads up is giving. People drive around for thousands of miles with their airmatic light on then get pissed when the pump completely fails and leaves them stranded. Same goes for sbc-neither are going to eff you if you address them when they are issues immediately. It is when you wait and hold off on getting it inspected, then it's the cars fault or poor engineering-nooooo, really it is consumer error/neglect.
Either way I'm hear to faithfully state that these vehicles do give you warning-what you intend to do with the warning is on you.
Side note- add up all the 211-219-230 chasis vehicles ever produced. The number of failures is no where near the amount of those models produced, not even close.
So in theory a heads up is giving. People drive around for thousands of miles with their airmatic light on then get pissed when the pump completely fails and leaves them stranded. Same goes for sbc-neither are going to eff you if you address them when they are issues immediately. It is when you wait and hold off on getting it inspected, then it's the cars fault or poor engineering-nooooo, really it is consumer error/neglect.
Either way I'm hear to faithfully state that these vehicles do give you warning-what you intend to do with the warning is on you.
Side note- add up all the 211-219-230 chasis vehicles ever produced. The number of failures is no where near the amount of those models produced, not even close.
