Do a search of the terms "disconnecting Mercedes Benz wiring connectors". They can be absurdly complicated - presumably because they don't want anyone to be doing repairs except MB dealers 😠 .

Is it anything like this?

 

Right, that was one of the first things I tried. I can't find a single image online that corresponds to the style of connector used on that pump. Take a look at it, the image is in the post It looks like, well, that - and not the same one as in that video (that one in the video looks intuitive enough to figure out at first sight!).

I'm glad to finally get a reply though, at least =) Something to kick the discussion forward. I'm really at a roadblock and considering whether I should fork over gobs of money to have someone actually diagnose it.

The only thing I can think of, and am increasingly suspecting, is that there's a second pump related to the battery pack that actually has the fault. This car hardly needs active thermal management at all (and it's surprising it does have battery coolant), so that would be why I don't notice any difference in thermals despite the pump error.

Of course we know a lot about the earlier Smart EVs, but does anyone know if the 453 has multiple pumps?

 

Right, that was one of the first things I tried. I can't find a single image online that corresponds to the style of connector used on that pump. Take a look at it, the image is in the post It looks like, well, that - and not the same one as in that video (that one in the video looks intuitive enough to figure out at first sight!).

Yes was was not suggesting your connector is the same - only that MB connectors are complex and non intuitive. And no I don't fine that 3-step manipulation of that white thing in the connector in the video to be intuitive at all.

I was having charging problems with my ED which isolating the problem required that I disconnect a connector on the on-board charger to do some continuity checks. I never figured how to unlatch the connector. The problem ended up being a broken pilot signal wire in the charging station cable

 

I had the same error, I replaced the pump and it was the same
I solved it by replacing the N127 module

 

Huge news!

OK, where is this module located? How much was it? I'm at the point where I'd almost pay someone for posting stories in this thread, haha. I'd rather pay someone here than pay $300 for Mercedes to simply look at it... and then another $x,000 to replace a $x00 part. I'm pretty savvy but this dang system has me blind... so seriously, if someone wants a donation somewhere for the advice, send me info on how to get it to you

The most recent hint I got from the Mercedes part department is that there are two pumps - one pump for the battery, and one for the power electronics (we know the PE pump is working). On the iCarSoft scanner, the code P0463F1 is found under the menu for "PTCU - Control Unit Powertrain (N127)", which does indeed track with what you say, and suggests that both pumps are working fine (if present) - since I have no faults for battery pump - just one of the pumps is not being sensed. This is why I quite wish I could figure out how to get that pump connector off as well

Given that I'm fairly savvy with electronic diagnosis & board repair, I might even be able to repair it, and provide that info here. Or at least, I can try.

 

the module is the rear luggage compartment on the right side, it is very easy to replace but must be program online
"PTCU - Control Unit Powertrain (N127)" here cost 160€ plus vat part number A493 900 76 03 it is a Renault part
See the prices on MB and on Renault
The pumps are Renault too (are much cheaper at renault)
To put conector out push the green part with a screwdriver at the same time pull the conector

 

Hey pmaf.iphone A493 900 76 03 this module is not located on on the back it is located under the stearing colum, are you sure this is the part number?

Thank you for helping us in this matter.

 

Awesome, thank you @pmaf.iphone 🙏 This finally un-sticks me and I will check this soon. To be sure, is it in the "engine" compartment below the rear floor, or is it in the main area of the rear compartment / "trunk"? I'm sure I can also find this soon on my own, but good extra info.

I've done a brief search but was unable to find any "N127 Smart" (that is correctly labeled) for sale on eBay, nor even "PTCU Smart" either. And that part number makes Google give me "the dumb look" due to all the spaces. I'm sure I can use it as useful reference using my other Mercedes tools, though. Renault isn't a brand for sale in the US, which limits parts I can shop for. I would definitely be willing to use a shipping proxy (appears as a UK address, for example, and then they re-ship the order to US) if I could buy the part from a UK/EU store.

Did you buy the part online, or did you grab it from a store? If bought online, would you be willing to share a link?

Thanks again - this has been greatly helpful so far and I might finally be able to get this back to normal soon

 

Right side on trunk, need to take off right plastic cover

You must find what is your N127 part number

Google Search

​

Google Search

I bought on a mercedes shop because it need to be program

 

Can't buy a used one if the ECU doesn't list that part number on it (453 900...)! That seems to only be applicable to ordering a new one, because as far as any parts reseller goes, the part number is ... well, one of the numbers printed on it (237...). If it ain't printed on it, it ain't getting sold under that number.

Needless to say I haven't been able to find any part with the 453 900 numbers. But I have found a few with the 237D40236R number and the 237D40151R number. Strange mismatch of alignments, don't understand what one number vs. the other number represents. One of them is listed strangely on eBay: only visible from eBay UK, says it's in United States, but shipping details/option selection specifically "excludes" United States. What kinda shop doesn't ship domestic? Very strange, so I'm sending a question about it...

You said...

I bought on a mercedes shop because it need to be program

... though, which means your replacement was a new part... how are you sure a used part would work? I suppose if they didn't, there would be no used market for them, let alone at such high prices... hmm. I really just don't want to end up buying it, and having lit more money on fire if it refuses to work. haha 😅

 

Google Translate says: "Hi, how did you change the module, how did you program it on your vehicles, is it possible to use a used module"

 

 

@Smarz I still haven't fixed it I still live with the "Malfunction, visit workshop" message every day. I found the ECU at least (behind the trunk trim, inside the car, rear-right side), but unplugging/replugging hasn't fixed it. Since I can verify the cooling system is working fine (temperatures look OK on all systems), I'm going to work on it later, after I'm done with a stressful move. I would still love to know any experiences anyone else has had - including non-Mercedes means of programming or acquiring a replacement ECU (in the US at least - or maybe I can use a shipping proxy from overseas if it'll work in my car!).

Copilot translation: Još uvijek nisam to popravio 😭 Još uvijek živim s porukom “Kvar, posjetite radionicu” svaki dan. Barem sam pronašao ECU (iza obloge prtljažnika, unutar automobila, stražnja desna strana), ali isključivanje / ponovno uključivanje nije to popravilo. Budući da mogu potvrditi da sustav hlađenja radi dobro (temperature izgledaju OK na svim sustavima), radit ću na tome kasnije, nakon što završim sa stresnim preseljenjem. Još uvijek bih volio znati bilo kakva iskustva koja su drugi imali - uključujući ne-Mercedes načine programiranja ili nabave zamjenskog ECU-a (barem u SAD-u - ili možda mogu koristiti posrednika za slanje iz inozemstva ako će raditi u mom automobilu!).

 

All right... finally moving on with trying to fix this. I've been pursuing trying to replace the ECU, to no success so far. Called around to a few local Mercedes/Smart specialist shops (third party shops) and they tell me they can't replace any ECU because of the coding. Only a Mercedes dealer with their special software can set up a new ECU. None were familiar with electric Smarts, though they tell me it's the same as with gas cars too.

So, at the moment I'm stuck with a dealer monopoly. Which sucks, since Tesla for example is a free/open system, able to reprogram a new ECU right in the car automatically - just swap and issue a reinstall/update from service mode, which is open to everyone/no external computer or web access required. Definitely not a great experience, coming from 5 years of owning a Tesla. :/

Add to it that none of the numbers on my ECU match up with the numbers for Mercedes/Smart parts catalogs (none of the "453900*" numbers match anything close to any of the numbers written on the ECU I have), and I don't even know what I would try to order if I could. At the moment my plan is stuck with going to a Mercedes dealer and asking for an ECU replacement - which I'll almost certainly have to do, given I already cracked-open the ECU and ruined its seals, hoping to find a bad soldered part but finding nothing. I was prepared to accept that, so no bad feelings there - just upset about the dealer monopoly thing.

Open to other ideas, as for now, I'm just waiting a bit to prepare my wallet for the gigantic cost...

 

If replace the ECU with a used one no need to coding
What is your ECU numbers?
It is Renault?

 

It is Renault branded - but it's an ECU designed by Continental (EMS3180), and also carries the numbers 237D40151R and 237D40236R. Aren't ECUs all keyed to the car's VIN? At minimum, if I get a used one and it's not the exact same config as my Smart, that could be a problem. DDT4All doesn't recognize this ECU, at least in the database I have. Amusingly, it recognizes everything else...

 

It is like mine, is not keyed to vin, mercedes part number 453 900 72 03
Can buy a used one with these numbers and replace

 

Ah heck, I found one with a perfect part-number match across both 237D40236R and 237D40151R, from that one that was in UK (but actually in US) - just found it on the US site, so I just bought it for $200.

I'll have it in the coming week, so I'll post back with how it goes! Fingers crossed. I figure if it doesn't work, I can still probably ask Mercedes to code it right. And if not, they offer free returns. But the price implies it should work fine.

 

I bought a new one from Mercedes for €160 and paid €50 to have it coded in a workshop with online access

 

Well, I got the new ECU today! It didn't need coding. It just dropped right in and the car started right up.

...

Started right up, for a few seconds without faults (yay! Happy, clean dash! No fault light!). And then, about 10 seconds after "run" while getting happily excited that there's no faults... "Malfunction - visit workshop". AARGHHHH...

Same exact problem. Same exact code. Same everything - no Cruise (can turn on, can't "set"). Drives fine, cools itself just fine. Well, the saga continues.

Now what? I think I need to find wiring diagrams and start digging into whether there truly are two pumps, one of which may have failed while leaving the other working fine. Seems odd, but I can't get a clear picture of what really is in this car (while it's mixed-up with its evil twin, the gas version of the 453). And I don't have a lift to easily and freely mess-around with stuff, so I really need to get advance information/research before digging into the car - especially if I want to keep driving it while figuring it out.

 

Are you sure the NEW ECU is good?
I think is not

You can check rear pump when the car is charging:
Put the hand on it to feel if it is working
You can see the coolant running in the expansion tank

Try to find someone with a similar car so you can try an ecu that is good
that's how I did it

 

There's a 0% chance that two ECUs in a row are going to have an identical, obscure fault that precisely no other people on the internet have ever reported (I'm the first person to ever write "P0463F1" it seems - the only results are my own posts now). Not only that, but it's the only fault it has. So I can definitely rule out the ECU and I'm not going to focus on it anymore.

I'm going to try digging into wiring diagrams and figure out what wires go where, and hopefully determine if there is more than one pump, where the sense wires go, how it gets its feedback, etc. Just need to find a way to get that info out of the labyrinthian Mercedes service software...

(and yes, the one pump I see is working fine. Under the hood, you can see it diligently squirting coolant into the bottle, circulating normally. It runs, and all the components stay cool)

 

Εγώ have the same problem P0463F1 I changed 2 woter pump and the same problem ☹

 

I also could be entirely on the wrong track, misled by a bad description of the error code itself - the iCarSoft scanner is the one telling me that it's a coolant pump fault, but Lord only knows where it got those definitions. It could be an entirely different problem (especially since "P0463" is a fuel level sensor fault on Renault cars - and this ECU is a Renault!). The fuel level sensor fault is, obviously, not rational for an electric vehicle though - so it's still got me a bit stumped.

If I could find any other way to retrieve fault codes and definitions, it could at least correlate some sanity if it matches, or disagrees, with the iCarSoft results.

At this point, we really just don't even know if it is truly complaining about the pump, or if iCarSoft is just sending me in circles. If the car itself could use its beautiful full-graphics dash display to display a fault code and/or message, that'd go a long way! Secondarily, maybe there is PC software (a la DDT4All?) or a mobile app that can interface with this beast and get me a second opinion. I do have DDT4All set-up and working (I was able to switch my lock mode to "unlock all doors with 1 press", hooray!), but it was unable to interface with this ECU - possibly because I lack the data file for it.

 

"There's a 0% chance that two ECUs in a row are going to have an identical, obscure fault that precisely"
I don't agree, I have 2 EQ smarts from 2017 and they both had the same error with approximately 80 000km
The cars never had any more errors
Here in Portugal there are more smarts that had the same error
With the Mercedes software you can check the insulation resistance, which can be measured with a good ECU and cannot be measured with a damaged ECU.

 

@FalconFour Have you managed to make any further progress? I had the same issue start a couple of weeks ago: same warning light, can't select a cruise control speed (or LIM speed). A local, independent garage checked it today used two code readers. One of them said P0463 and the other said P0463F1 - which brought me to this discussion.

I took the rear right side panels off today and my 2018 ForTwo EQ uses the exact same part numbers as yours. I'm waiting to hear for the price of the part from my local Mercedes dealer and the programming cost. But I suspect their reply will be that they want to test it first - I can just see the Euros adding up! My guess is that I'll need to go down the official Mercedes route as my local independent probably can't program a Mercedes part. My guess is that they need to be programmed to suit the particular car they'll be installed in (as you noticed yourself, the same ECU is used by multiple different cars brands).

Please let me know how you get on and I'll also update my own situation here.

 

Not need to be programmed to suit the particular car but must be programmed with the latest software

 

@smc I'm still in limbo (still all the same original symptoms). Waiting to get a chance to get the car on a lift and be able to inspect the SECOND cooling pump that's behind (/above) the aero panel in the front of the car. I can obviously tell that the power electronics cooling pump - attached to the motor in the rear of the car - is working fine, and coolant is flowing... but the battery loop pump may not be (I think it may borrow/circulate coolant through the power electronics loop, or through a heat exchanger somehow, but not sure how it all works).

Finding a chance to lift the car or get it in a position where I can get that whole aero cover off and be able to poke around under it is the hardest part, so it's taking a bit.

 

I left my ForTwo at the local Mercedes dealer today. They said they were able to do a more thorough diagnosis than just an error code read. I got a call later in the day and everything they said was consistent with what's been said in this thread. They read the code and used some Mercedes(?) software to command the coolant pump via the ECU, but it failed. So they were then wondering if it's the ECU at fault (just as we've mentioned here), so tomorrow they'll test the coolant pump with a direct power feed (not via the ECU). If that works, then they'll order a new ECU from Germany. The interesting thing is that they told me that would be ideal because replacing the pump is actually more expensive than replacing the ECU. ..I'm guessing that's because they'd need to refill the coolant again...?

I'll post more updates here when I have them.

 

@smc - did they make a distinction whether it's the battery coolant pump (in front, behind the shroud) or the power electronics coolant pump (exposed, attached to the motor in back)? In my case, the coolant is visibly flowing in the bottle under the hood when the car is on or charging, and everything is charging/driving just fine. If the power electronics pump weren't running, I'd expect it'd overheat while charging or driving, and give other issues (possibly damaging other things, too).

My current suspicion is that, since the ECU has two coolant pump circuits, it's that other pump that's legitimately failed, especially since I can't really monitor battery temps (frustratingly, neither my OVMS nor the iCarSoft scanner seem to show battery temps). No way to monitor that pump, control the pump, or get a more clear fault description either. So I'm still a bit blind until I can get under there and look at it.

But yeah, ... replacing the ECU is fairly easy (15 minutes), while replacing that battery pump would be a fair bit more daunting.

 

No, they just said, '"pump". I can ask them when I collect the car, though. The new ECU should arrive mid week and I should get the car back by Thursday.