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Discussion Starter · #1 · (Edited)
Good Morning,

I have a 2015 Smart Fortwo ED. This morning I came outside, unplugged the car from the charger, turned the key and I was greeted with many errors one was a "brake system failure" (I didnt hear it run), it mentioned a "HV System Workshop", "Do not tow", and then said to go for service. The traction battery was at 100% this morning. I did a quick google search and identified its the 12v battery.

I ran to the autozone picked up an H5 battery and swapped the original. The car now turns on, I can open the windows, the brake booster turns on but I am still getting a HV System Workshop error. The HV battery is still at 100%.

1. The car is now drivable - despite the error.

2. The car charges successfully from the 240v.

3. We regularly drive the car, it has 10,200 miles on it and it was last driven yesterday evening.

Searching this sub forum, I cant definitively find if there is a way to get past this error or if I have to take in.

I would really appreciate some direction on what to do next or how serious this error is.

Thank You

P.S. When I originally made this thread, the car wasnt drivable - it sat for 30 minutes after the battery swap and came back to life.
 

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Discussion Starter · #2 ·

Found this thread. Looks like its a trip to Mercedes with prayers they can reset it and upgrade the BMS in the process. Of course, more importantly it looks like this is not a BIG problem. Just a minor inconvenience.
 

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Discussion Starter · #4 ·
What if you disconnect your 12 V battery for 30 min? More a "try it" than an it might work.
To be honest. I'm wary of experimenting with it. Everything I am reading here says it's an error code written into some module that only the STAR tool from MB can clear.

I was just wondering if there was any development in the years since this issue has existed that would allow me to wipe it.
 

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Fast try would be the cheap Autel MaxAP200. With this you could reaet already most of the easy failure. After this you need a Xentry or more exact the DAS Tool included for Smart 451. You can build this easy if you search for Pass Thru version and use a cheap Jtag 2354 Dongle like Openport2 in a chinese version for small money. Overall for 250 Bucks you even can get the luxus version :)
Depending where you are located there are often some MB fans which own the tool and can help out.
 

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Discussion Starter · #7 · (Edited)
Problem solved - took a little research but I learned a lot about the current state of diagnostic tools and found a device that worked. The bonus is I didnt have drive into Manhattan and leave my car there. I didnt want to go with the Autel AP200 because I didnt want to pay $60 and then have to pay more to use it with other cars. I didnt want to go with the Autel MK808 because it doesnt do module activation and only gives 1 year of free updates. Though to tell you the truth, who knows how long any of these companies will be around.

So I found a device that worked and worked perfectly and the price was right. It has a bluetooth OBD dongle, it supports activation of modules (if I ever need it) with a subscription, has lifetime free updates, reads all modules, all resets and all makes forever.
https://www.amazon.com/dp/B09BNLXPL5/ref=cm_sw_em_r_mt_dp_0H10J8Z9S8481F1XS82K

It identified errors in the BMS and the Traction control unit and let me clear all of them. However, clearing the BMS was not enough. The error on the dash only disappeared after the Traction unit control module was cleared. I was even able to email myself a PDF report of the BMS.

Anyway - I'm sure the Autel would have done it as well but I figured may as well have the whole device especially since its on sale now and may come in handy later on since I do work on cars sometimes.

Rectangle Gadget Font Wood Display device
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Discussion Starter · #8 ·
You can also see here that it allows access to various sensors for a live data stream. Truthfully, I am shocked at how nice this device is.
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At the end of the day, my wife is happy she can continue driving the car she loves and I am happy I dont have to deal with taking it somewhere and losing a day of work.
 

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Hmmm, i see this tool could delete easy failure codes in ECUs but not give the right text for even simple failures .
So to just delete the failure codes it is really easy to use a cheap blue ELM327 dongle.

But to dig into the ECUs and get all failure codes and maybe start coding and flashing it seems to be way too expensive and not support these features. But never the less a nice tool and also allow to read out other cars.

And it helped you to solve your issues. Perfect!
 

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Discussion Starter · #10 ·
Hmmm, i see this tool could delete easy failure codes in ECUs but not give the right text for even simple failures .
So to just delete the failure codes it is really easy to use a cheap blue ELM327 dongle.

But to dig into the ECUs and get all failure codes and maybe start coding and flashing it seems to be way too expensive and not support these features. But never the less a nice tool and also allow to read out other cars.

And it helped you to solve your issues. Perfect!
What do you mean "but not give the right text for even simple failures"? The descriptions of the DTC's are right there.

I dont see how its easier to use an ELM327 when you would need to have some kind of program to be able to interface with the computers in the car first. Besides that, what are you looking to "code and flash"?
 

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For example in the first picture of the second post the first failure code is not known and just a referenz to the manual is given.

For sure for elm327 it is real tricky, but a life hack which could help you in case you own nothing else.

If you could code and flash, you could activate the paddles. They are easy to add to any original steering wheel. Also to the two spoke version.
And you could easy activate the additional brabus power and recuperation modes :) Believe me, if you have driven a Smart with this activated options, you will get a addional smile on your face :)
 

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Discussion Starter · #12 ·
For example in the first picture of the second post the first failure code is not known and just a referenz to the manual is given.

For sure for elm327 it is real tricky, but a life hack which could help you in case you own nothing else.

If you could code and flash, you could activate the paddles. They are easy to add to any original steering wheel. Also to the two spoke version.
And you could easy activate the additional brabus power and recuperation modes :) Believe me, if you have driven a Smart with this activated options, you will get a addional smile on your face :)
Oh! I understand you now.

I have an ELM327 that I bought a long time ago. Honestly, my wife drives this car to and from work 6 miles round trip so I I dont need to overclock it or add paddles.

But out of curiosity, how would you go about interfacing to these modules with an ELM327?
 

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All the ECUs use the UDS Protocol for diagnostic. So a simple DTC clear command to the right CAN Id will already delete the stored failure codes.

So depending which unit you wanna clear you only need tp send just 2 commands via a terminal tool for free on a mobile connect to the ELM327 via bluetooth.
 

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Discussion Starter · #14 ·
All the ECUs use the UDS Protocol for diagnostic. So a simple DTC clear command to the right CAN Id will already delete the stored failure codes.

So depending which unit you wanna clear you only need tp send just 2 commands via a terminal tool for free on a mobile connect to the ELM327 via bluetooth.

Is there a guide on how to do this or at least a tutorial to follow in order to get started? Is there a white paper that outlines a vehicles modules or at least a modules can id and commands it accepts? How is a connection initiated with the can bus?

Can you give me an example?
 

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Ok short ELM 327 tutorial

ATSH 7E5
04 14 FF FF FF 00 00 00

By this comand one unit on the bus with the physical address 7E5 and the backchannel +8 means 7ED will configured to wait on can commands

In this case always 8 bytes as DLC. The UDS protocol is inside the CAN frame

04 means the command uses 4 bytes

14 FF FF FF means all failure codes schall be cleared
The following
00 00 00 files the frame
There will hopefully a answer but you could check for it the web.
7E5 should be the N127 CEPC
7E7 should be the BMS
But i need to check. Normally i am not on this deep level.
 

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Discussion Starter · #17 ·
Ok short ELM 327 tutorial

ATSH 7E5
04 14 FF FF FF 00 00 00

By this comand one unit on the bus with the physical address 7E5 and the backchannel +8 means 7ED will configured to wait on can commands

In this case always 8 bytes as DLC. The UDS protocol is inside the CAN frame

04 means the command uses 4 bytes

14 FF FF FF means all failure codes schall be cleared
The following
00 00 00 files the frame
There will hopefully a answer but you could check for it the web.
7E5 should be the N127 CEPC
7E7 should be the BMS
But i need to check. Normally i am not on this deep level.
But how did you find out about the module addresses and the commands?

I thought you said this was "simple" and a "life hack" and so far it's anything but that.
 

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I admit I am a bit confused where the discussion goes here, if clearing codes with the ELM doesn't get us back on the road. though I'm an electrical engineer, I have no experience with car ECUs. I do have some experience with microcontrollers and programming, so it would be interesting to understand why, if we can literally write to an address and change a value with devices like the ELM 327, why we can't write that P180151C address and reset the thing. Are certain EEPROM areas password protected or something?

On a side note, we need Right to Repair laws immediately, this is total bullshit what Mercedes did to us here. I know our farmers and others are working on it. I should probably take this to small claims court. Probably just throwing good money after bad.
 
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