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I am wonder is someone can help with this one that started happening a couple of months ago and gradually getting worse.
It seems overnight in particular but not always I appear to loose all electrical, No Dash, No crank, no interior lights, no boot, no seats and probably other stuff.
Magically if left for some time it spring back to life and all works as normal.
What I have found so far when this happens is that circuit 30 has a healthy 12 vols but not 30g ( measured at rear fuse box) when life comes back so does 30g.
I am think the K relay in the battery compartment fuse box fuse box or what drives it. I have ordered a new relay.
It is weird because once pocking around the rear fusebox I lent on the carpet and came good, so I thought loose something, next time all the poking and prodding in this are did nothing.
Another time I closed the rear door (nearly slammed) and all cam good. Next time nope. Maybe coincidence.
When the relay arrives I will dismantle everything for a look.
So for the last few day no go but magically this afternoon al good again however I did notice that the clock reset along with the "trip details since reset". Maybe since it has been sitting for a few days.
I really don't think it is battery as said circuit 30 is healthy but not 30g when this happens.
Does anyone have any suggestions as to what else to check from what I am reading it may not be the relay, but fingers crossed?
I am wonder is someone can help with this one that started happening a couple of months ago and gradually getting worse.
It seems overnight in particular but not always I appear to loose all electrical, No Dash, No crank, no interior lights, no boot, no seats and probably other stuff.
Magically if left for some time it spring back to life and all works as normal.
What I have found so far when this happens is that circuit 30 has a healthy 12 vols but not 30g ( measured at rear fuse box) when life comes back so does 30g.
I am think the K relay in the battery compartment fuse box fuse box or what drives it. I have ordered a new relay.
It is weird because once pocking around the rear fusebox I lent on the carpet and came good, so I thought loose something, next time all the poking and prodding in this are did nothing.
Another time I closed the rear door (nearly slammed) and all cam good. Next time nope. Maybe coincidence.
When the relay arrives I will dismantle everything for a look.
So for the last few day no go but magically this afternoon al good again however I did notice that the clock reset along with the "trip details since reset". Maybe since it has been sitting for a few days.
I really don't think it is battery as said circuit 30 is healthy but not 30g when this happens.
Does anyone have any suggestions as to what else to check from what I am reading it may not be the relay, but fingers crossed?
Regards
To all
You have power that goes entirely missing... clock and trip reset!!
Before considering faulty hardware you'll need to scan the chassis to learn what computers have to say.
Do not unplug anything (modules, fuses, relays) on powered car sleeping or not. This will only get things more disfunctional.
My top suspect for ALLPWR MISSING: Oxidized MAIN CHASSIS GND STRAP : nope!
Oxidized MAIN BATT GND STRAP : yes!
Battery connections and prefuse condition.
candy twist
This is an unusual failure... something in the vehicle history must be odd.
Last edited by CaliBenzDriver; Jan 6, 2025 at 02:26 PM.
Good call always open for a different view will post results.
Bear in Mind circuit 30 constant 12volt supply is fine it is 30g that drops power, that loosing power (not coming back on more to the point) will throw many errors as well.
Good call always open for a different view will post results.
Bear in Mind circuit 30 constant 12volt supply is fine it is 30g that drops power, that loosing power (not coming back on more to the point) will throw many errors as well.
Best Regards
post the diagram so we all get on the same page
Circuit 30G controller is the prefuse K2 relay?
these are hard to toast but not impossible especially if tested bad - Perhaps oxidized connection along the route...
We'll make this all good ... and then some with bonus to cancel more chaos!!
Last edited by CaliBenzDriver; Jan 6, 2025 at 03:44 PM.
If only you were here, I am sure a few beers and a BBQ can solve anything (at least till the morning)
Diagnostics:
#1 is interesting
#2 Ignore
#3,5,7 EIS maybe the faulty solder connections ??? (how do you get that thing out), would this do it consider, hmmm
#4 ignore I know what that is, need to replace the sensor
#5 no comment
#6 & 7 Well no circuit power no coms I suppose
I will look up the codes - they seem to be talking about the EIS but still trying to decipher
I read somewhere about the K2 relay, will replace it on spec - at least will rule it out.
If only you were here, I am sure a few beers and a BBQ can solve anything (at least till the morning)
Diagnostics:
#1 is interesting
#2 Ignore
#3,5,7 EIS maybe the faulty solder connections ??? (how do you get that thing out), would this do it consider, hmmm
#4 ignore I know what that is, need to replace the sensor
#5 no comment
#6 & 7 Well no circuit power no coms I suppose
I will look up the codes - they seem to be talking about the EIS but still trying to decipher
I read somewhere about the K2 relay, will replace it on spec - at least will rule it out.
I here what you are saying it is also the first time I have seen that error.
I did scan the last few times this happened.
However if that is the case where to from here I suppose is the question
BTW I am an electronics trade person of dubious character so have a little knowledge which can be dangerous. BUT MB circuits thats another story all together.
I here what you are saying it is also the first time I have seen that error.
I did scan the last few times this happened.
However if that is the case where to from here I suppose is the question
BTW I am an electronics trade person of dubious character so have a little knowledge which can be dangerous. BUT MB circuits thats another story all together.
from here the next step is concentrate on No1 fault: this is top issue
You being a smart electronician, we can take a shortcut...
Let's do "tap-tap" on F-SAM relays one at the time... any direct improvement
if not youll need to schematic to pin point the name and location of the "consumer" relay thats likely oxidized
FSAM I assume you mean the relay box in the engine bay?
Sort of been there done that but will do with a focus next issue occurrence..
I have the Manual and printed out most circuits around this will delve into this area and also see where the interior lights get their power, probably 30g
FSAM I assume you mean the relay box in the engine bay?
Sort of been there done that but will do with a focus next issue occurrence..
I have the Manual and printed out most circuits around this will delve into this area and also see where the interior lights get their power, probably 30g
yes, exactly
the engine bay fuse box doubles as a power Mgt computer (F-SAM) and network gateway (CGW).
F-SAM also remotely controls the PreFuse K2 Main Relay which maybe your trouble maker.
> TROUBLESHOOTING....
Are you ready to go reading line voltages using schematic?
At this stage, we have this cornered into a simple case... bad relay or bad GND.
Last edited by CaliBenzDriver; Jan 7, 2025 at 05:46 PM.
I actually did a quick voltage scan this morning and noticed all circuit where flat line at similar voltage except for, you guessed it, 30g!
I is varying up and down around up to around -0.5 volts. An uneven grumbly signal. I will try and record it. If I were to guess it looks like a not so good connection somewhere. I will have the relay this week and need to delve down there for another reason so will change it on spec and re read the voltage but it could indicate relay contacts. The Fsam is certainly interesting. My little baby is running fine at the moment so bit hard to diagnose while all is well but I can still poke around while monitoring the voltage.
I actually did a quick voltage scan this morning and noticed all circuit where flat line at similar voltage except for, you guessed it, 30g!
I is varying up and down around up to around -0.5 volts. An uneven grumbly signal. I will try and record it. If I were to guess it looks like a not so good connection somewhere. I will have the relay this week and need to delve down there for another reason so will change it on spec and re read the voltage but it could indicate relay contacts. The Fsam is certainly interesting. My little baby is running fine at the moment so bit hard to diagnose while all is well but I can still poke around while monitoring the voltage.
this gives you a bit of time to study for a surgery day: Plan A + Plan B...
To recap we are dealing with the circuit tha powers dashboard clock
I actually did a quick voltage scan this morning and noticed all circuit where flat line at similar voltage except for, you guessed it, 30g!
I is varying up and down around up to around -0.5 volts. An uneven grumbly signal. I will try and record it. If I were to guess it looks like a not so good connection somewhere. I will have the relay this week and need to delve down there for another reason so will change it on spec and re read the voltage but it could indicate relay contacts. The Fsam is certainly interesting. My little baby is running fine at the moment so bit hard to diagnose while all is well but I can still poke around while monitoring the voltage.
this gives you a bit of time to study for a surgery day: Plan A + Plan B...
To recap we are dealing with the circuit that wales up the whole car right... not waking up every time?
Beware that besides electrical it could also be :
-- chassis ignoring/not finding your keyfob
-- bad Networking between keyless and CAN- B
Let's keep a open mind until we have proven bad electrical. It's a Mercedes: faults can be different than what they appear to be.
🤞
Last edited by CaliBenzDriver; Jan 7, 2025 at 07:55 PM.
It is getting worse deal ATM, 12v at 30 not 30g. Could be no wake up.
Did this yesterday as well came good 20min later ??????
I do have an open mind on this just getting frustrated now about where to start.
I have read that the EIS connections can fail inside the unit do you know if the EIS could be part of this issue, and how do you get the thing out?
Regards
-- you're onto something.... indeed solderless EIS key slot module is built to become unstable sooner or later (ISM also). Loose pins can be soldered better than new under 5mn without need to reprogram anything.
-- It also acts as a local gateway so it does spread more troubles when ghosting.
-- To get hold of it is not a cake-walk, for security reason. Every unit assembly is a bit different... give it some time and you'll succeed.
Last edited by CaliBenzDriver; Jan 12, 2025 at 11:10 PM.
So I got the EIS Out it is a new style with clips so just comes off easy.
I could not see anything wrong at all, but I soldered all the solderless pins anyway.
Put back in and (touch wood) been fine for the last week, and actually for some reason feels happier.
In the old days we used to re-seat PCB's and plug in chips, I think similar happening here.
Seems like those press in pins are failing. Clever way to sell modules I suppose.
So I got the EIS Out it is a new style with clips so just comes off easy.
I could not see anything wrong at all, but I soldered all the solderless pins anyway.
Put back in and (touch wood) been fine for the last week, and actually for some reason feels happier.
In the old days we used to re-seat PCB's and plug in chips, I think similar happening here.
Seems like those press in pins are failing. Clever way to sell modules I suppose.
Thanks for you help and fingers crossed.
Well Terry, that's great: you've successfully made your EIS more reliable than new.
I had a similar experience so i hunted every last loose pin module on my chassis. That made the weekly display error message to stop.
Eventually I discovered the engine lag is forcing the tranny to shift poorly due to variable voltage. Here is ALT-LIN enhancement...
Last edited by CaliBenzDriver; Jan 21, 2025 at 02:25 AM.
I'm battling very similar problem for past 3 weeks with 2012 ML350, 130k on it. when cold hit Massachusetts. If temps above 25F no issues, all works well, if below no luck getting power to dash... trunk open/closes fine with remote, interior lights on, hassar light works fine, does not look like battery as well. After locking/unlocking car for 10 or more times sometimes it recovers. Wondering if this could be related to AUX battery ? Yesterday while driving, and coming to stop car decided to switch to Park..... good we have snow on road, probably would of lost transmission.
I'm battling very similar problem for past 3 weeks with 2012 ML350, 130k on it. when cold hit Massachusetts. If temps above 25F no issues, all works well, if below no luck getting power to dash... trunk open/closes fine with remote, interior lights on, hassar light works fine, does not look like battery as well. After locking/unlocking car for 10 or more times sometimes it recovers. Wondering if this could be related to AUX battery ? Yesterday while driving, and coming to stop car decided to switch to Park..... good we have snow on road, probably would of lost transmission.
There's a good chance your issue is caused by a cold relay. Hook up a Launch scanner to get whole chassis report. Else wet finger random guessing is gonna be costly.
There's a good chance your issue is caused by a cold relay. Hook up a Launch scanner to get whole chassis report. Else wet finger random guessing is gonna be costly.
Thank you so much for reply. I will try to find someone with scanner. When you saying cold relay, is there specific one I should check/replace. I found a good link, which has all fuses/relays.
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