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I have some trouble with the Electronic Parking Brake Module. Not with the parking brake it seems. The trouble became apparent as I had a battery power drain. Descending form the battery (engineprefuse to interior prefuse to rear SAM tot fuse 130) it became clear the Electronic Parking Brake Module (A13 in the scematics A2214302949) was acting up. According to a readout with my Icarsoft diagnstic tool the parking brake is "pulled" without reason. Anyone an Idea what might cause this? I see lots of problems with this module, but almost all are motor related. Not this ghostly behavior.
Last edited by lli; Aug 4, 2021 at 11:46 AM.
Reason: type in part number
the release can be automatic (as in drive off it works it out and takes it off), to achieve this the ABS sensors have to tell the car its pulling away. The rear sensors fail to time (usually 9 years) and over 6 months the park brake gets more erratic till it pops up on screen with an ESP fault. Your first clue might be a few extra bongs for the internal nags about what's happening and or it was off when you know you put the park brake on, and or it won't auto release
other than that they are designed to die after x count of use. The "idea is to pretend its a safety thing and the mechanism is worn... the reality is they like to take money out of your pocket... It can be reset for many more years of happy successful use. See also SBC brakes on a E class.
are you finding they aren't holding the vehicle? I'd start by servicing the rear brakes making sure the discs and pads are in serviceable condition and the pads move freely - whilst it should auto adjust sticking brake pistons are common and make this less likely to land... you can (not sure how - they did it on mine) tweak the level of play till they apply with less nose and time... but it soon settles back to normal. I forget but I think I get 3 clicks as it applies
the counter can be got at by various diagnostic kit - but it will have cut out in software and throw teddies - rather than works intermittently
The EPB holds the vehicle just fine. I rarely use the EPB as the Netherlands is a flat country.
The problem is that it engages and disengages itself, without me applying the EPB at all. It also does this with the vehicle locked (engaging/disengaging), thus draining the battery overnight. That is the problem I have. As far as I know nothing to do with the EPB motor, of pad wear.
how old is the car? I don't think it will cause a power drain. More likely the battery is old or something else causes it. If its 2007 or earlier in the boot with be a monster 25kg battery.... if the original AMG pull the bungs out and top it up and give at least 24 hours of charge it will be 80% of a new one after a few weeks.
the park brake being off and or not coming off is usually the ABS sensors failing
Well, what can I say, the multimeter and car diagnostics point to the EBS as the user of all the current (fuse 130). Battery is fine, OEM and keeps sufficient power.
As said: The problem is that it engages and disengages itself, without me applying the EPB at all. It also does this with the vehicle locked (engaging/disengaging), thus draining the battery overnight. That is the problem I have.
As far as I know nothing to do with the EPB motor, of pad wear. No issues on the wheel speed sensor as far as I can tell. And with the car not in motion, would be strange. Wheel speed sensor trouble would also lead to Distronic and ESP trouble, and there is none.
So in short my quesiton: has anyone's EPB module gone crazy like this? Is repair possible, or should it be replaced. Is new (1000 euro!!!) or used an option? Or the ones from aliexpress?
Well, what can I say, the multimeter and car diagnostics point to the EBS as the user of all the current (fuse 130).
As said: The problem is that it engages and disengages itself, without me applying the EPB at all. It also does this with the vehicle locked (engaging/disengaging), thus draining the battery overnight. That is the problem I have.
As far as I know nothing to do with the EPB motor, of pad wear. No issues on the wheel speed sensor as far as I can tell. And with the car not in motion, would be strange. Wheel speed sensor trouble would also lead to Distronic and ESP trouble, and there is none.
never heard of the park brake play up the way you describe - but it does have a count down to death - even if you can't reset - decent diagnostics should give the readout, I think its 1 million operations on E class brakes upped in a software update from 600k. I find it odd you use the park brake that much so doe sit die at 100k ? My snap- on stuff doesn't show the EBC on an E class - whereas I didn't just find the counter in Autel - I can reset it !!!!)… Oddly never got round to looking for either on the S class park brake
My wheel speed sensor made the park brake play up for 6 month before the ESP light came up.... 4 new sensors all back to normal for last 3 years.... How do you know its off with the doors locked? Are you sure its not going odd as you unlock / turn the ignition on... that what mine would do and I'd often get an extra audible bong, but it took me 3 months to realise it was the car and not the driver being forgetful
I don't dispute the count down, I think it is a different problem. The EBS is going odd when the vehicle is in rest. Turned of. I tested that with the general approach to parasitic current use: latch the doors and bonnet (open but the door registers as locked), let it go into rest. That takes about 30 minutes to be sure. But duing that time, current was craze. 4A! That is not normal for a locked vehicle. As said, going down from the battery using an amp meter and a precise voltage meter, it came down to the EBS module. Remove fuse 130 and all trouwble was gone. So yes, I'm pretty sure it is the culprit. But that is not a solution to why it is acting up. It could be it is getting it's instructions to pull the parking brake cables form somewhere else. However, then the system should not go to sleep as it now does without fuse 130.
I've made an appointment at my indi, see what he thinks of my diagnostics.
a loaded S class w221 uses 37 amps with the ignition on (and not started) and doesn't not sleep for quite some time after locking the doors and walking away, some stuff shuts down 7 minutes after locking, but its quite common on modern cars to only sleep after 30 mins
I have some trouble with the Electronic Parking Brake Module. Not with the parking brake it seems. The trouble became apparent as I had a battery power drain. Descending form the battery (engineprefuse to interior prefuse to rear SAM tot fuse 130) it became clear the Electronic Parking Brake Module (A13 in the scematics A2214302949) was acting up. According to a readout with my Icarsoft diagnstic tool the parking brake is "pulled" without reason. Anyone an Idea what might cause this? I see lots of problems with this module, but almost all are motor related. Not this ghostly behavior.
Olá! estou com uma C250 W205 com o mesmo problema ... ela trava sozinha ... o DTC é B23AA1D "O VALOR DE ENERGIA ESTÁ FPRA DO CAMPO ADMISSIVEL. Já encontrou solução ?
just re read this post - the park brake is applied mechanically via bowden cables (grown up version of the brake or gear cables on a bicycle), any wear or damage can lead to a stretched outer and at this takes up slop the force might vary, as would heavily worn discs with wear or ridges in the drums, over heating brakes that are big when brake put on then shrink as they cool (common issue on some GM cars allowing the vehicle to move after parking). Or wheel bearing slop, dust build up, brakes shoes falling apart etc.
all could give a change in reading, but it shouldn't change once set - the thing puts the brakes on mechanically, with force generated via an electrical motor, that's driven by electronics, it then stops doing anything - its not live 24 7 - so if the OP is getting current down wires when it shouldn't, that suggests wiring shorts or module confusion somewhere on the car doing something its not meant to
mine started being odd the other day - never played up before but just randomly wasn't holding
it was cold wet and horrible - so I just flashed a later software version at it and magically its working normally again.... I wasn't surprised its just a crooked world now
Jumping in here ... I wonder if you have a similar problem to the one that I have - where the Bowden cable is starting to deteriorate. Mine manifests itself by the EPB failing to release - always an inopportune moments, of course. If yours was jamming in the other direction it's possible that the motor might continually try to pull on the cable and engage the brake. I would expect the actuator to get sifgnificantly hot over time so you might want to check that.
On a separate note - does anyone know where I can locate the right hand cable for a 2008 S550? I have the left hand one but have completely failed to locate the right hand cable. My alternative is to replace the enture actuator assembly for $750 - a lot more than the $100 for a new cable!
As an alternative does anyone know if its possible to get these cables repaired (replace the inner cable, fit new ends etc.)? Once upon a time this was common practice but these days we simply replace ever larger modules and throw things away ... <mute> ... rant ... </mute>
in the UK lots of places refurbish and send it back - but I don't think merc want you to find the cables..
with the dealer kit you can 'set up' the brake force. You are meant to do this after changing the unit or replacing the brake shoes for the park brake
I did mine in the summer, it is easily inside the brake force required and stays stable - I then found the time to death counter and its at 60% - so the fact mine isn't holding might be cable related - I even adjusted the shoes but its not helped - its strange you feel it grab the car and hold it then as you put in park you feel the park brake DELIBERATELY release till its held on the box pawl - its a lottery 3 times its 100%.... next it will release a bit)
not USA - looking for this found loads of ads for aftermarket brand new units
I am having same issue with my W221 2012 model. While the car is off, there occurs an intermittent high amp drain of 7Amps. Caught the culprit at EPB fuse and removing it solved the drain.
However, I am still not sure if it is the EPB module waking up by itself or the EPB Switch triggering it to turn on somehow. I have now disconnected the Switch and reconnected the EPB module fuse to hash out if its the switch instead.
I don't dispute the count down, I think it is a different problem. The EBS is going odd when the vehicle is in rest. Turned of. I tested that with the general approach to parasitic current use: latch the doors and bonnet (open but the door registers as locked), let it go into rest. That takes about 30 minutes to be sure. But duing that time, current was craze. 4A! That is not normal for a locked vehicle. As said, going down from the battery using an amp meter and a precise voltage meter, it came down to the EBS module. Remove fuse 130 and all trouwble was gone. So yes, I'm pretty sure it is the culprit. But that is not a solution to why it is acting up. It could be it is getting it's instructions to pull the parking brake cables form somewhere else. However, then the system should not go to sleep as it now does without fuse 130.
I've made an appointment at my indi, see what he thinks of my diagnostics.
not sure - I think I'd start looking for puddles under the carpets, under the bonnet in the SAM box, or in the boot.... either a module is breaking down, or I guess a canbus system is in a puddle and getting confused
any issue on a W221 start off checking out batteries - there was a post weekend gone by - seems they have a Small Aux - motorcycle - battery (not under the dash but in the boot on the CGI cars)
@beingapoorv In the end I bought a new EPB, but it did not solve the issue. So, the fault most likely comes from somewhere else. Probably a person that can follow the instructions backwards can identify the sensor at fault. I suspect the wheel spin, or steering wheel sensor, as I had problems with these before. I imagine (but this is nothing more than a complete ignorant putting in less than a cent) that the wheelspin or steering wheel faultly detects movement in stationary state and therefore resets the EPB.
In the end, the fuse of the EPB was switched with the ignition key. So as soon as you turned of the car, the EPB would remain in the state it was in before turning of the ignition. Not sure ig this hack is advisalble in mountainous terrain, but in the Netherlands, not much risk can come from it.
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