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While the British article above identified K2 as the cause of cars going powerless, it did not identify the root cause of high currents killing k2 in the Prefuse module.
I point uncontrolled discharge swings as the root.
As we know already, the "Quick charge" voltage gets controlled directly at the battery terminals. This caters exactly to the voltage needed regardless of any inline drops.
With a worned out K2 relay dropping voltage under abnormally high 80Amps "charge" current, the voltage on the alternator side of K2 relay will be compensated for the drop with a higher output: 16..17v to satisfy the battery sensor.
Electronic caps in some controller modules are rated at 16v max... This over-volting translates into mutiple modules failing or prematurely aging from unexplained reasons in affected cars.
I wonder what aged K2 in the field looks like?
What we've seen is normal charge currents are modests and should not top a fair value: 5...10...20A?
INCENTIVES... $ SAM!:
Up above we've seen how the AUX battery charge circuit relies on Relay/MosFets... - Same principle: keep the charge current normally low. Don't ignore your AUX battery or it may fry a $1 chip off your SAM...
We've gone pretty deep to unravel fancy breakdowns conditions: PreFuse, SAMs.
The simple take home is normal currents prevent extensive troubles.🤗.
Last edited by CaliBenzDriver; May 7, 2021 at 02:27 PM.
The additional battery is permanently charged after battery state recognition when the engine is running.
The additional battery is charged via the front SAM control unit. Charging is only interrupted for as long as it takes to run the battery state recognition.
The charging current is limited by means of a resistor to P = 15 W. A diode prevents the additional battery from feeding back into the on- board electrical system.
Yes
As per my post at #167 , that seems all we can know about it and it is the N10/1 Front SAM is controlling it .
Your should be safe, no V19 Relay-Diode combo like B03 option ECO start stop.
If I am correct, it seems that small G1/7 1.2Ah battery duty is only so that when main G1 battery goes flat, you still at least can engage P in transmission , hence N73 Ignition Lock seems to be the
only "customer" of this battery. Only 1.2Ah, I doubt it can do much.
While the British article above identified K2 as the cause of cars going powerless, it did not identify the root cause of high currents killing k2 in the Prefuse module.
I point uncontrolled discharge swings as the root.
As we know already, the "Quick charge" voltage gets controlled directly at the battery terminals. This caters exactly to the voltage needed regardless of any inline drops.
With a worned out K2 relay dropping voltage under abnormally high 80Amps "charge" current, the voltage on the alternator side of K2 relay will be compensated for the drop with a higher output: 16..17v to satisfy the battery sensor.
Electronic caps in some controller modules are rated at 16v max... This over-volting translates into mutiple modules failing or prematurely aging from unexplained reasons in affected cars.
I wonder what aged K2 in the field looks like?
What we've seen is normal charge currents are modests and should not top a fair value: 5...10...20A?
INCENTIVES... $ SAM!:
Up above we've seen how the AUX battery charge circuit relies on Relay/MosFets... - Same principle: keep the charge current normally low. Don't ignore your AUX battery or it may fry a $1 chip off your SAM...
We've gone pretty deep to unravel fancy breakdowns conditions: PreFuse, SAMs.
The simple take home is normal currents prevent extensive troubles.🤗.
The K2 overtime will fail for sure. However I see the consolation here is that K2 is not in duty cycle like a contactor for a big electric motor.
I mean K2 is placed by MB as means of control for certain section of N10/1 and for my car it seems 100% of N10/2, so K2 is not an active switch like how a contactor is for big electric motor.
So less arcing for K2 use, compared to a contactor duty. However, K2 residing at F32 is very HOT area neighbouring to the real engine bay, unlike industrial control panel housing a contactor...which will be at ambient temp.
The only worry I see for K2 is when it starts to age and giving intermittent issue and not in complete failure mode. The troubleshooter will suffer.
I do not know about K2 duty/task software side , I can only comment on its mechanical side.
About potential over voltage output of alternator being fooled say by bad contact at K2 output, that we need to look at as a possibility.
Need to confirm where the real voltage sensing takes place for such decision commanded to alternator.
So far we only know about battery sensor B95 at main battery negative and I can confirm by the dashboard information, from the 16 seconds of ZERO CHARGING event we discuss,
the positive feed of the dashboard voltage information comes from the battery post itself and that means from Pyrofuse.
What we do not know is, the command to the alternator via its LIN .....on voltage output required.... are there any other sensing region like N10/2 or etc etc , will software be involved ?,
......to finally produce the voltage command to the alternator ?
and here's the data sheet for a chip that implements both LIN 1.x and 2.1. https://www.infineon.com/dgdl/Infine...6d5d74fb3a0492
skimming that, it looks like it if there's no LIN communications but the alternator is spinning, it enters a 'default operation mode' where it relies on a set of pre-programmed (NVRAM) registers to supply fixed values which should like they SHOULD be set to put out a 'safe' fixed charging voltage like 13.8 or 14.4, but we have no way of knowing what values those default registers are set to on the Mercedes alternator.
Last edited by Left Coast Geek; May 8, 2021 at 01:08 AM.
I hope I am correct here.
Why I said so above is : Simply because MB way of making a 1 super page of schematic containing all known global options of their car models and specific wiring needs.......
is very confusing if one does not remove ( part of the schematic) what his car doesn't have.
I have looked at this very carefully, lets assume I am correct.
F32, for my car, has 3 power sources/wires delivered to N10/1 Front SAM.
1 is K2 controlled and 2 is not. So total 3.
So , in my case, when and if I have K2 issue, I need to see N10/1 crazy long schematic and figure out which Zones control what components
One can not think for a minute that there is only 1 connection/wire to N10/1 from F32.
So think of N10/1 as a Front Main Electrical Panel of W212, where inside it has 2 more sub-panels.
Then... have big cup of coffe, print out N10/1 , and strike out what wiring is not for your car/option.... then start troubleshooting.
Yes LCG, I seen that link sometime ago.
It does scared the hell out of me, because it showed how advance the alternator is , which in turn may allow MB engineers to write complex instructional software to command this alternator to do
what they could never do before when alternator was still kinda dumb. All these in the name of emission reduction.
Once a software is involved, it is game over for me... I am IT dummy.
The same reason I got frustrated when I was searching for headlight "ON" command for Low Beam and High Beam thinking it was still analog, in a post where I asked what is 30L wiring code ?
You were the only one who took time to reply to that post.
2016 E350 4Matic wagon, 2019 Ford Expedition, 2019 Chevy Bolt EV
It would be interesting to disconnect the LIN signal from the ECU to the Alternator, and see how it performs. have a volt meter on the system before you start it, and shut it down quickly if it goes too high. If it was properly programmed, the alternator *should* revert to 'old fashion' mode where it always dumb charges as long as its spinning.
of course, the alternator could work fine, and the ECU might still throw a hissy fit and toss ODB codes around.
I don't have any issues with software that I can get my hands on or is at least reasonably well documented. black boxes, however, are frustrating.
It would be interesting to disconnect the LIN signal from the ECU to the Alternator, and see how it performs. have a volt meter on the system before you start it, and shut it down quickly if it goes too high. If it was properly programmed, the alternator *should* revert to 'old fashion' mode where it always dumb charges as long as its spinning.
of course, the alternator could work fine, and the ECU might still throw a hissy fit and toss ODB codes around.
I don't have any issues with software that I can get my hands on or is at least reasonably well documented. black boxes, however, are frustrating.
The energy management document did mention that if battery sensor B95 get disconnected, it will revert back to traditional 14.3V or something.
I do not know the LIN disconnection though.
I am attaching F32 General Version and My Most Probable version as B03 ECO Start-Stop based on my datacard. Who knows this can help someone in the future.
This word file , you guys can use it as a high-res super long sideway JPEGs.
This is probably the V19 relay-diode combo and the so called K2 below : ( same image in the WORD file )
I do remember a comment in the tech literature, something along the lines about not "switching" too often (due to wear)... I believe related to it checking the auxiliary battery SOC. I guess it's relative, because eventually it'll wear out... just what is the lifespan expectation.
Since I am preparing for next charging test ( still rigging the car ), might as well test to confirm on the V19.
Just to confirm about the DIODE part of V19 Diode Relay Combo. ADD : 15 May 2021. For the test below, the negative cable of battery to the chassis ground on top of strut is removed. That is to make sure the Relay part of V19 does not engaged , or else I can't read the voltage drop across the Diode ONLY part of the V19.
. 15 may 2021. Above illustration is incorrect.
15 May 2021, below is the correct illustration.
I am beginning to think BeachBunny case of 3 total battery changes in 3 years on a 2015 E350 ( ECO version for sure ) , this post https://mbworld.org/forums/e-class-w...ml#post8326583
could be a "borderline-deteriorated" contact point of the V19 Relay Section, bad production batch perhaps. Not easy to detect this kind of fault because driving it , is NO ISSUE by position of alternator at F32 bus bar, but charging is the issue as
any charging to main battery must go thru V19.
Adding the B03 ECO start stop unique charging characteristic for the discharge behaviour, the MB tech may not realize V19 was the slow-but-sure charging deficit culprit, but only when a certain temperature and amperage threshold is reached
I would love to troubleshoot that car if I am allowed to total loss the F32 , blow an alternator to death for fun of test and damage a battery, all at owner's cost
Last edited by S-Prihadi; May 15, 2021 at 04:06 AM.
Reason: add correct info
Already 65,750 ppl soaked in all that quietly before me.
Tell me MB has never heard of these problems and is clueless about the cause of this poor ownership experience ("on affected cars", yes!)
Most systems are well managed through CAN'ed controllers but some module self-check come up real short: Prefuse has none outside F-SAM.
To the few fearless owners who might consider buying a look-alike AUX battery:
-- AUX has to assume (steering) power when battery and alternator get cut-out...
-- You need a reliable AUX up to OEM specs !
------------------------------------------------------------------
> Quick Tips to consider with low batteries:
-- Simply keep both your batteries well charged to "help minimize" rogue charge currents.
-- A power ON/OFF restart on the road is a quick way to reset glitched computers and Limp-Mode, possibly an early warning.
-- Learn to recognize the signs of damaged relays to prevent getting stranded powerlessly - True across all cars sharing the same components.
-- Automotive failures are properly engineered to gently worsen. Learn to recognize the progress steps and seek repairs on time.
------- Paradox:
-- Prefuse relays suffer internal breakdown despite great looking specs on paper with epoxy encapsulation.
-- 80 Amp current draw in a 250 Amp relay should fly a long time without problem!
- K2 failure mode seems sensitive to HEAT as if internal grease gradually turned into sticky gum
- Relay V19 in some instances seem to have been upgraded to solid-state MOSFET for gentle ramping instead of ON/OFF surge.
Last edited by CaliBenzDriver; May 9, 2021 at 03:20 PM.
Reason: -Tips / -Paradox
So, I found who made the V19 relay-diode combo.
This V19 has no mechnical parts at all.
Its all semiconductor. Some sort like solid state relay, but with diode blocker ...kinda.
2016 E350 4Matic wagon, 2019 Ford Expedition, 2019 Chevy Bolt EV
Wait, I think the exhaust system I put on our W124 1990 300E 2.6 was Eberspacher. hah hah. it was exact original replacement, fit perfectly with the OE style clamps and donuts and hangers.
Here is what I found out.
Based on : W212 Model year 2014, B03 ECO Option and with ECO 12Ah trunk battery.
Engine OFF Test conditions :
1 – Locked doors.
2 - Key far away.
3 - Wait for 12+ hours.
4A – Hood stay open, hood lock mechanism not “tricked” to lock.
4B - Hood stay open, hood lock mechanism manually push to lock.
4A and 4B I wait for 12+ hours before measurement.
Based on #1 to #4, V19 Q-Diode working parameter is always ON ( closed circuit /latched ).
AA. V19 will only un-latch if the ECO algo takes over when ECO mode is activated. That is V19 primary design goal.
BB. ( ENGINE RUNNING ) V19 also will un-latch, within a few minutes after engine started where we see the Zero charging by the alternator to main battery as per Instrument Cluster.
ECO mode choosen or not, BB is SOP for cars with ECO B03 option.
CC. K2 relay will be open circuit ( un-latch ) pass the 6 hour mark.
My car being in the tropic and has no heater options like 4 season countries, car’s domestic electronic management + A/C cooling fan consumes approx 25 – 37 amps. This is WITHOUT electric power steering being used
at fast rate and high angle of change. Electric steering sucks a lot of power in full speedy duty, 40+ amps is possible. No wonder the cables to it is the biggest for a single device I seen on my car, perhaps the
radiator fan would be the same size…but I never pay attention to fan yet.
DD. During engine run, 12Ah trunk battery always get charged after the car algo decided so, in approx 3-4 minutes after engine start. NOTE : I am NOT using the ECO mode.
I believe there are 2 versions of charging to the 12Ah trunk battery and not the simple 1st method of 15watt limited by resistor from front sam N10/1 claimed by the tech document GF54.10-P-1060FL Engine on energy management, function.
The 2nd method is when the relay K114 of the 12Ah battery is latched/closed and hence 12Ah trunk battery get parallel to main G1 battery at engine bay and get the alternator output too.
Prove : Sometimes the ECO battery can get 3 amps, but short burst few seconds. On average it is 0.8 to 0.9 amps.
To get the clamp meter decently accurate to 0.5 amps, there is a way to do it
So above is 69.8 amps of gross alternator output. Battery get 34.5 amps and the rest 35.3 amps is for car electronic domestic management/consumption.
A/C is ON for sure, but radiator fan is not at 100%.
. The data acquisition process for 10th and 14th May 2021 test:
01. Dumb me, 14 years ago I installed the same shunt based amperage meter on my boat and I forgot that it is a Negative based meter.
Can not be used at positive side, because reference 0 volts wont be available.https://www.bluesea.com/products/823..._-_500_to_500A
I will need another kit called SHUNT SHIFTER if a positive side is where I will use it. https://www.bluesea.com/products/8242/DC_Shunt_Shifter .Wasted so much of my time....agghhhh
Current clamp will auto shutdown within 20 minutes, hence I initially decided to use shunt.
02. Extend alternator cable for current clamp use. Use my wireless current clamp. Place clamp in coolest possible location. Remove A/C blower air intake baffle to make room.
03. Sending wires into cabin from engine bay.
I been wanting to explore this cabin to firewall/engine bay hole for new cables. So I used it, temporary rigging for now but is rainproof.
.
.
04. 12Ah ECO battery at the trunk. No choice, camera based recording and with typical 20 minutes auto-shut off for both the DMM and Clamp Meter.
I wish I have a much lower power video light with very diffused light.
05. ECM T1 and T2 temperature reading spots.
I have always wanted to read the ECM temperature. 90C continuos and short run to 120C is the design limit. Must test the ECM temperature in my 35 Celsius Jakarta traffic jam and of at least 2 hours drive.
This document above is from : https://link.springer.com/journal/35...nd-issues/74-6
MTZ worldwide, volume 74, issue 6, June 2013.
If anyone wants to read about M276.820 3.0 Twin Turbo
Still 10th May 2021 test, with alternator output being read.
Below you will see an 8 seconds of Zero Charging, starting at time code 03:35.xxx
The V19 Q-Diode is un-latched, so V19 becomes DIODE only mode....so alternator can not charge main battery.
Alternator is feeding F32 Bus Bar and all load connected to it, except the main battery and you can see alternator voltage at 13.87V while battery at 13.0V to 12.9V.
Due to 0.8V to 0.9V lower the main battery is compared to alternator, albeit there is diode allowing current to flow from main battery to F32 bus bar, alternator wins and
is then the sole power provider for F32 Bus Bar. So we see Zero Charging at main battery and none of discharge, the diode and voltage difference made that happen.
I seen similar thing happening like above in a yacht 24V DC system, where alternator output voltage of main diesel engine is lower by a mere 0.8V or so than the also running battery charger* ( *powered by stand alone diesel generator ) as such
the battery charger took 95+ % or more of the total DC load of the yacht.
==============================================
Below is 14th May 2021 test.
No more amperage data out of the alternator and no voltage + amperage data from ECO 12Ah battery.
The idea of this test is while I am carbon cleaning my engine with 4,000+ RPM most of the time, I hope to see the charging algo decision making between acceleration and de-acceleration.
This 11.8 volt is the lowest voltage I seen on the Control Module ( N3/10 aka ME-SFI control unit aka ECU/ECM ).
Too bad the traffic density can't allow me to do more brisk acceleration, so all I can do is keep RPM constant high.
To cut short the video, I have edited only 6 minutes of frequent discharging, in real time, no speed up or slow-motion.
Minute 12:00 to 18:00 only from the total 48:00 minutes.
Apology for my swearing at video time code 17:39 and up. I always swear when in front of me is a tall car and with crazy dark tinted rear window.........coz I can't see what is in front of it and
that can means my luck depended on how attentive the driver of the car in front of me is and how good he is at seeing potential problems needing maximum braking force.... ahead of time. My dash cam is at the left of the in-cabin rear view mirror, so it can see better than me being on the right side of the car ( right hand drive ).
The timeline using Time Code is as follows :
The test duration was 48:00 minutes.
Engine start to minute/timecode 12:19 is all charging.
12:20 is the start when the algo deemed my battery is fully charged and started the frequent discharging sequence untill engine kill at minute 48:00.
Here we can see that monitoring ONLY voltages at Control Module and OBD2 pin #16* ( *N2/10 Rear Sam ), does not tell the whole story.
As to why MB algo designer "failed" to recognize the Control Module can be as low as 11.8 volt during battery discharge, it is for us to guess and wonder. Whatever he is having...I want some
I saw a video of someone repairing his E500 W211 front SAM N10/1 and it showed how "sissy" the PCB board housing the relays and all fuses, if we equate this PCB to a Main Fuse Panel and the Bus Bar.
If the W212 is still/also having this kind of "sissy" PCB as Bus Bar, I am not suprised the voltage drop is so severe for N3/10 aka ME-SFI control unit aka ECU/ECM.
Screen captures from the E500 W211 video
.
Fuse #27 position for ECM/ECU in my car, a Right Hand Drive.
*** Ignore MB's arrow for front of car, that is for Left Hand Drive**
If you take a closer look at how the E500 W211 PCB is designed , I think the copper trace is not that big/thick enough.
Now imagine the N3/10 fuse being the last one, at the end of the Bus Bar* ( *copper trace) so to speak, higher voltage drop will result.
I would love to see PCB for N10/1 fuses and relays like below :
Imagine, the power wires sizes feeding N10/1 from F32 Pre-Fuse are not small.
MR7 terminal of F32 to N10/1 is 150 amps fused using 16mm2 wire.
MR6 terminal of F32 to N10/1 is 60 amps fused using 6mm2 wire.
MRG2 or MG2 of F32 to N10/1 is 100 amps fused using 10mm2 wire.
Sad. Seems there is nothing I can do to reduce the voltage drop at ECM/ECU N3/10 , lousy sissy PCB and baby sized power cable using 0.75mm2 for N3/10 ECM/ECU
from N10/1 Front SAM...what worse can happen ?
.
Last edited by S-Prihadi; May 16, 2021 at 10:42 AM.
Reason: typo
So above is 69.8 amps of gross alternator output. Battery get 34.5 amps and the rest 35.3 amps is for car electronic domestic management/consumption.
A/C is ON for sure, but radiator fan is not at 100%.
Great stuff! This caught my eye... as I recall recording charging data on our car. When the charging profile was in alternator management, the voltage was ~ 12.6 VDC... but the current was alternating between +/- 5A. I thought that was odd, at only 5 amps. This explains it, as IB is the current at the battery and not TOTAL charging output.
Yes BMW, the reason people could missed this is because the schematic of F32 does not show ( failed to show is a better word ) the presence of B95 battery sensor at the main battery.
B95 battery sensor is managed by Rear SAM N10/2.
B95 is visible at Wiring Diag for Engine Start/Stop
I have pointed this out at post number 160 , 4th image/schematic. https://mbworld.org/forums/e-class-w...ml#post8330418
I think MB is only interested in knowing what's happening to its main battery G1.
MB could add positive side shunt dedicated for alternator output, if they want more data.
They then can call currently the IB as IB1 for whats pumping IN/OUT of battery, and add IB2 as purely alternator output.
Surya, these smart alternators already publish all their data over LIN to R-SAM for the ECU. The alternator is built around a LIN Chip that runs its own software logic.
The original Bosch design uses a battery sensor to micro-manage any power going in or out of the battery. The goal is to calculate the battery charge level. It has a "calibration cycle" to discover battery charge and actual capacity factoring its age.
The various charge levels are used to guarantee the capacity to enable the ECO restart function.
Any additional charge from 80 to 100% is collected for free while coasting, all the way up to 100% when charge strictly stops.
From 80 to 100% alternator backs off to 12.6V float voltage unless high consumers command a higher power output.
Battery relay/MOSFET isolator:
The only thing standing between the alternator and the main battery is the beefy V19 "relay" (misc: thick cable, 350A fuse, pirofuse and battery sensor on neg. side). Some cars feature a classic SPST relay, the later one got the solid-state electronic version.
Self-test cycle:
when the cluster displays IB:"0.0" during AUX batt connection, it is a good sign V19 has main battery well isolated showing a null current.
If V19 junction was compromised there would be an obvious leakage with high Amps current (not mA).
When turned on V19 is nearly transparent without any significant drop. They seem to handle high currents well at least while cooling keeps up with chip dissipation.
The built-in flyback or body diode protects the silicon junction from any destructive reverse voltages - They're tough but not indestructible from dried out heatsink grease! (Autopsy needed)
😎
The engine Starter load hangs directly off the battery post without tangling with F32 prefuse circuitry.This guarantees minimum dropped voltage for 100Amp* cranking.
+++++
(*) cranking Amps is displayed as "100A" but was measured with a clamp meter around 350Amp and up according to engine size etc..
Last edited by CaliBenzDriver; Nov 6, 2021 at 09:19 PM.
That makes sense Cali. Thanks.
Nevertheless, I have to live with most of the time after engine kill, is having 80% charged battery.
Well, at least my stand alone CETEK charger can do its work once or twice a week.
I guess what I will do next time when its time to change the main battery is to log the new one ( fully charged), see how it behave at 5 amps discharge on a bench
Create a voltage drop profile loaded and unloaded after X hours at 5amps discharge to say maximum 6 hours.
Then every once a year, test that 1/2/3 years old new battery the same and see the downhill performance slope.
I have never done a bench test voltage drop profile on any of my car battery as above, perhaps it will be useful.
At an assumed 80% charged after engine use, the current 3 years old battery at approx 3ish to 5 ish amps discharge is reading 12.38V and 12.65V if unloaded.
The 3-5 ish amps is from my A/C blower which will power itself a slow speed after approx 30 minutes engine kill. This I think is how it blows out remaining water vapor in the evap.
Maybe next time I should time the start and the duration of the blower auto-run.
This is based on Varta Silver Dynamic AGM , 80AH.
ADD : Cali, I will do the voltage drop at K2 relay soon yah.
Now that I permanently have 2 core 18AWG wire standing by in engine bay... , can experiment a bit more.
Last edited by S-Prihadi; May 17, 2021 at 02:14 AM.
Reason: ADD TASK
K2 is downstream, not involved between alternator and battery. K2 directly feeds both SAM's
Low voltage and high currents create higher drops so high consumers cause the R-SAM logic to request higher alternator voltage... on normally working cars - Others drain the AGM below 80% 🤣
Example, front cooling fan uses around 800W power at top speed:
under 14.4V that's 55Amps
under 12.6V that's 63Amps
8Amps more to get the same power!
✌️
Last edited by CaliBenzDriver; May 17, 2021 at 03:18 AM.
Hello all, new member here. I recently acquired a ‘13 GLK350 and it has been plagued with this exact problem of low charge and discharge while the alternator is running. I’m glad I found this thread, as it has helped me tremendously with diagnosing. All the countless hours of research and trial-by-error put in by everyone here, to what has led me to my particular solution.
I had flickering lights (interior and exterior), watched the battery voltage and amperage on the IC read ~+12.4VDC and -3.8A to +42.9A (engine on) and ~+10.8VDC and -9.6A (engine off). My batteries were MB dated 11/2018 and load tested at +12.4VDC (main) and +11.2VDC (aux) after charge. I also had several faults popping up (FR ABS speed sensor, SRS, IAT, AUX Battery, and traction control). I broke out my meter and found I had +12.4VDC on the battery terminals, but when using the jumping posts, I had +10.8VDC.
Hmm, so I pulled the prefuse panel and after tedious amounts of gentle prying, I found the relay post to the battery had heated to a point of melting (deforming) the plastic around the post’s base. It had also deformed the cover side where the brass sleeve insert is pressed in. Here is what I found.
I proceeded inward and after a ton of gentle prying and coercion, I managed to open it and found this.
Notice the relay, how the tin coating has blued from excessive heat and the plastic deformed, as well. This created a massive amount of resistance, since it is used to encase everything. Melted plastic made it’s way in between the connection points, so I trimmed all of that back and put everything back together, purchased new batteries from O’rielly’s (Super Start AGM by JCI) and set them each on charge while doing this job to ensure full power.
With fingers crossed, I unlocked engineering mode on the IC to view the battery output…+12.8VDC and -9.7A. 😩 So I went ahead and started the engine with little hope of success, but to my surprise, battery went to +14.5VDC and 3.4A after a minute of idling. 🙌 WOOHOO! No more flickering lights, no more faults on display, and stable alternator output!
This may be an isolated incident, but hopefully this may be a solution for more than just me.
Finally someone showed me/us how a V19 Q diode (relay) looks like from underneath. Thank you Riles.
That is B1 terminal/stud which overheated.
Seems like a loosen contact, which is factory fault as no one would mess with F32 pre-fuse unless troubleshooting something.
A1. The sort of white stain below at the link (bus bar ), what is that thing ?
A2. The face/side of the link (bus bar ) with stain, that is not the face which goes to the V19 Q diode terminal, its opposite face is... correct ?
B1. The link (bus bar) share the same stud/post which its plastic melted...yes ? I marked red. ( This will make clear for my question A2 )
B2. Do you have wide angle photo like below's video of the F32 opened up ?
It is different your F32 prefuse terminal numbering. Perhaps because yours is a GLK .
In my W212 your terminal MR1 is my MR4 and so on and..... your MR4 is my MR7
My MR3 is your MR7 if I read correctly.
My MG2 and MR9, I can't really read well from your photo.
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Slideshow: A one-of-one U.S.-spec Mercedes-Benz SLR McLaren Roadster became even rarer after a factory-backed transformation at McLaren's headquarters.
oldie but goodie
https://www.bluesea.com/products/823..._-_500_to_500A
, lousy sissy PCB and baby sized power cable using 0.75mm2 for N3/10 ECM/ECU
