Gents,

I am doing some testing on Fuse 5 if removed/blown scenario.
I done this many years ago, but was using iCarsoft MB v2.0 as scanner, now I am using Xentry for better result and correct DTC.

Fuse 5 is rather unique, as it serves 4 modules as Circuit 15 , but I think this is not used as power supply, but rather analog +12V information to other modules that Relay J is active.
Circuit 15 is from output pin 87 of Relay J.




On my facelift car, I can confirm that the wiring of Fuse 5 at Front SAM sheet 2 and sheet 10 is correct for the number of wires and color of wires at :
Sheet 2, connector 11C pin 11 is for Exterior Light Switch S1, using 0.75mm Red wire. Coordinate F55.
Sheet 10, connector 11C pin 11 is for A1 Instrument Cluster, using Red with pink tracer wire. Coordinate F38.
As to why sheet 2 or 10 does not show both wires at connector 11C pin 11, but instead separately shown on Sheet 2 and Sheet 10.......I don't know.

Front SAM Connector 11C, pin 11 actual wire color and quantity.
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I can also confirm for the S1 rotary light switch, that indeed 0.75mm red wire is for S1 at connector 2 ( only 1 connector actually ) pin 4


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Sheet 2 of Front SAM N10/1




I have not tear down my A1 Instrument cluster, so I can't confirm if 0.75mm red with pink tracer wire goes to A1.
Below is Sheet 10 of Front SAM N10/1


For Fuse 5 above, I can confirm the wire colors and the quantity of 2 wires black with blue tracer one of 0.75mm and 1 of 0.5mm at Front SAM connector 7I ( I as in i ) pin 6.

To my eyes both black with blue tracer wires are 0.75mm at connector 7i pin 6.




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So basically 4 modules get this "power" of Circuit 15 from Fuse 5.

Without engine running yet, only ignition ON engine OFF or key position 2 ( ready to crank), I get DTC only from 2 modules.


I can still operate my S1 rotary light switch for Low Beam, parking Left or parking Right or rear fog light and even its backlight is ON.
Instrument Cluster A1 normal ( engine is OFF, remember ).


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The favor I am asking : ....................

Can someone be kind enough to do Fuse 5 pull out when you are about to start your engine and let your engine run a bit with fuse 5 out, apply the brake too and run a scan with a decent scanner,
see what DTC do you get ? Thanks in advance.

I will do the same Fuse 5 pull out again....when it is time that I use my car on the road. I can't do short engine run in garage for the time being.
I shall update my findings.

As to why I am very curious on Fuse 5 is, it may one day be an issue hard to track if ever bad contact occurs on fuse 5. Our car is aging and oxidation on wire and connector is part of aging.
If fuse 5 blown, I guess it is easy now that we know at least 2 DTC will appear as I shown.

Thanks

 

You are interested in testing fuse failures to discover what impact plays out. You're going to find many special combinations.

I am always looking out to help but I have no spare car. W212 is now my DD: I've just rolled passed 80k. Miles driving up/down California hills.


80,000 Miles is better than new

When part of a module power supply goes missing who knows exactly how it is going to disfunction. Modules use multiple types of power sources to enable their logic.


implausible status

Network partners are going to report unusual faults.
By studying schematic it's impossible to forecast exactly what may happen... hence a fuse survey can help fill that gap.

 

You are right, some Circuit 15, " is not used as power supply, but rather analog +12V information to other modules".
Circuit 30 is almost permanent voltage supply and some modules ( at least in the past) need Circuit 15 trigger signal for going to sleep or woke up.

For engine ECU the logic is like this:
- circuit 15 power up or trigger the wake up the digital part of the ECU and the FBS system send over CAN that the Drive Authorisation is OK the Circuit 87 become active and the ECU becomes fully powered.

 

Come on Cali .... just 20 minutes max.

 

I will measure the current load at fuse 5, just for fun.

 

Is that fuse test result not too satisfactory on your chassis?

Perhaps nothing much seems to happen - So it's both good + bad test.


@trigital says this 12V line supplies an analog "Power-ON" wake-up signal. It does not flow current only active signal level.

I know the fuel tank pump module and the radiator fan module and... uses that type of dual signaling logic as a backup.

You can test many/all modules under these same conditions. Perhaps the headlights modules would be most interesting to fully test for bad signaling.


The conclusion may be that dual Power-ON signaling works well for VIP fail-safe:
-- XYZ modules stay active despite missing signal ?
-- Perhaps not all 100% modules respond well ?

 

I will do it tomorrow morning Surya, Report back after I do. I have the 3.5 276 NA and a pre-facelift '12 model W212, so let me know if that's helpful or not

 

Thank your sir
2012 model its okey, good for database .

 

Just to update on A1 instrument cluster supposedly Fuse 5 is for A1 too.




Fuse 5 is to A1 Instrument Cluster if the car uses NETWORKED exterior light switch S1.
Mine is a NON-NETWORKED exterior light switch S1, because I removed it once before ( see post 1 ) and able to find the 8 pin connector USING 6 wires ....which is only for NON-NETWORKED exterior light switch S1.


Above is the NEWORKED vs NON-NETWORKED exterior lights swicth S1, which you can not tell from exterior looks or even the rear azz, which will show the very same
8 pins connector. Unless you verify the connector for S1 from the car and start counting wire numbers and colors, you will never know if yours is networked or non-networked.




There are 4 Part Numbers for S1 light switch if I choose my car model as W212.065 and without VIN number.
A2129050551 <--- Mine
A2129050951
A2129050851
A2129050751
All these 4 types, all look the same for the rear azz connector of 8 pins, unless we see the number of wires from the car to the S1 light switch, we will not know
if ours is Networked type or Non-Networked type...duggghhh

Mine


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All 3 other versions of S1 switch




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I am also having trouble identifying the wiring dates vs my car year of modification date.
I think it left Germany on 30th Aug 2013 as semi knocked down, later assembled in Indonesia as Model Year 2014 car and sold to 1st owner by June 2014,
the official Indonesian Birthday paper ( BPKB ) for my car is 6th of June 2014.

In EPC it is easy, my car is 804 . which meant YOM 13/1 , YOM = Year of Modification and not MANUFACTURING...
So my car wiring wise, I am supposed to use up to January 2013 wiring or up to Feb 2013 ??? WTF !!




In EPC it is easier to ID my car as 804.





In wiring diagram, me a bit confused, because it seems a true facelift wiring is after March 2013 ??? is it ???



If I am to use ---> 02/13 ( up to Feb 2013 ) wiring, it does make sense that Fuse 5 is listed but ONLY if my S1 light switch is NETWORKED type.
By the wiring 03/13 --> ( after March 2013 ) , Fuse 5 is no more listed for A1.

The funny part is, according to WIS Facelift Information , M276.8 engine in my car is a July 2013 modification. I am attaching the document.



So why am I using a Feb 2013 wiring, if my engine is only available April 2013 updwards
I really hate when the car Year of Modification Date aka YOM , is so close to change of date in the wiring diagram.
Why dont MB wiring engineers do it like EPC parts guy, use 803, 804 or 805 instead for dates on wiring diagram.

So here we can also see that Front SAM fuse list never had updates. Even in WIS 2020, it seems the Front SAM fuse list is STILL of year 2009 when W212 first debut.

I don't think I will ever go to the extend of removing my A1 instrument cluster, just to confirm Fuse 5. I fear breaking fragile plastics on the dashboard trims.
Therefore I shall never be able to confirm if indeed Fuse 5 wiring goes all the way to A1 or not, or if indeed it goes to A1 , is there any male receiving pin for it at A1 ?

The only other non-intrusive way we can confirm Fuse 5 relation to A1 Instrument Cluster is a networked switch S1 car, participate in Fuse 5 pull out and hopefully the scanner
can detect DTC from A1 Instrument Cluster claiming Circuit 15 is lost or not available .

End of Rant

 

Power consumption of fuse 5 with Ignition ON, engine OFF is only 11 milliamps.
I used special fuse adapter


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With engine RUNNING, it can be up to 24 milliamps.
So this is confirmation that Fuse 5 is merely a +12V signal called Circuit 15, it is the analog information to the receiving modules that this +12V is alive.





FUSE REMOVAL - SIMULATED




Move car forward and reverse in garage. No DTC for ESP/ABS at all on Instrument Cluster.. See the video below :
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But the typical DTC for N30/4 ESP/ABS and N10/2 Rear SAM does exist....as usual.




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REAR SAM N10/2
Something I learn today, which is the weakness of Xentry PassThru. My Xentry C4 is out of action, due to overheating. So I use PassThru with genuine OpenPort Tactrix 2.0.
I was trying to read ON BOARD ELECTRICAL DATA, but failed. My Xentry C4 can do it.


.

I can't find the Circuit 15 from Front SAM which is what the DTC is all about, too bad. I can only see Rear SAM own's set of Circuit 15-s. Relay A, B and G.



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There is wiring diaghram of each module connector which as far as I know, is only found in Xentry software and not in WIS or EPC.
See below, connector for A1 Instrument Cluster, supposedly based on my car type/VIN and should be accurate.


So Xentry said, there is no Fuse 5 Circuit 15 +12V injection to A1 Instrument Cluster, as seen by connector pin assigment.


Below, the Front SAM sheet 10, still has such drawing and we are read the VALID for on NOT VALID for yada yada.


So I think, based on Xentry drawing of A1 Instrument Cluster connector pin out, my car does not use Fuse 5 for A1 and also probably because my car uses the NON-NETWORKED exterior light switch S1.


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The question still lingering is = Why is loosing Fuse 5 ( circuit 15 ) to ESP/ABS module is not critical ?
I mean I assumed with no hard DTC showing ESP/ABS disabled at instrument cluster, my ESP-ABS is still working.

Also to rear SAM : loosing Front SAM circuit 15 power ( fuse 5 ) signal at Rear SAM ... what function will be impaired at Rear SAM ?

 

without fuse five I get "Unable to communicate with ECU" everything works and I got no codes or check engine lights, I reinstalled it and got no codes either while starting and running including shifting and braking

 

Well noted, with thansk.
This 2012 is M276.9 engine already yes ?

 

I had a similar issue on my 2022 S580, turns out the Front SAM fuse 5 controls the park sensors, so if you're having trouble with them, check that out first.

 

Yes, first year I believe, I think the '10 and '11 were 272's

 

2022 S580 is W223 chassis...right ?
It probably does not share much similiarity to W212 family for Front SAM fuses designation.