capth00k

2010 E350 4matic -- having a problem , when I floor the car it seems to go into limp mode w/ the ESP unavailable message. When you turn the car off it goes back to normal. Have already replaced the accelerator pedal with a used one, but the same codes persist:


630900 - Component B37 Accelerator pedal sensor or control module 'motor electronics' is defective
Position Sensor 1 for the acceleration pedal has a short to positive


With my scanner I checked the pedal readings and they seemed fine when viewing the live data stream, and I checked wheel speed sensors (all fine) .. also performed the throttle body reset. Also reseated / inspected the two connectors to the ECU on top of the intake but all looked pretty clean. I've heard this can occur from a bad MAF, but mine isn't throwing any codes. Some sources state I should check component N3/10 ? ... clean the female harness to the accelerator pedal? ...

CaliBenzDriver

This is extremely similar to this W211 thread.

You get a limp mode with DTC about APP

For me :
"Component B37 Accelerator pedal sensor or control module 'motor electronics' is defective
Position Sensor 1 for the acceleration pedal has a short to positive"... reads like a signature for missing ECU GND posts.

​​​​​​Some of which can be well hidden on the engine side of the firewall as well as interior footwell.
Keep track while you clean as many as you care to.

> Hands-On:
Clean all ECU GND points.
Test drive to see any improvements.
Scan the car.

As needed: repeat with ESP GND points


Else it's going to get involved to figure which of ECU or ESP is tripping the other one ...

🤞

capth00k

Thanks for the reply -- Will attempt to locate the ECU ground connection in the footwell area tomorrow -- drivers side? like from your previous post on ground connections

CaliBenzDriver

Yes, it's not difficult and very rewarding to help sanitize these cars.

Your ECU lives on the engine crown, mine is on the left side over the exhaust pipe - I think both of these different styles still GND on driver footwell.

> Clean... GND posts in order:

1. driver footwell
2. passenger footwell
3. driver engine side firewall
4. ESP area under side of front frame beam

Do disconnect BATT while your juggling with GND posts as footwell GND is used by F-SAM: the car Power controller VIP.
​​​​​​

It's interesting that your limp-mode gets reset by power cycling the ignition... there's a pattern right there about these soft-crash limp-modes....
Let me ask, is your instrument cluster voltage display while flooring any good or does it deeps below 12.3V ?????

The ECU firmware backs down the ALT load during accelerations and your car likely has the early Bosch "Smart charging" controlled by ECU... it has some weaknesses.

capth00k

Ok here are some pics, cleaned the ground connections I could find today and the one behind the emergency brake pedal (footwell). After that and reseating a bunch of connectors - I took her for a very spirited drive - and into the corner which normally seems to set this off (flooring it into a tight right) and the problem did not reoccur at least for now (fingers crossed) . I could not locate the other grounds in the footwell besides the one photographed, but it was pretty clean. Also didn't test or monitor voltage before ground cleaning - but the voltage did not fall when floored and seemed pretty stable.







Data from the ESP unit at idle, sitting in the driveway (not level) - lateral acceleration seems to go 0.14-0.16

batt voltage without motor on

wheel speed sensors fine

voltage while running

CaliBenzDriver

Great, you have covered a lot. Everything you show looks fine, in particular the voltages seem perfectly aligned with expectations.

One thing I miss though is additional driver footwell post.

look half-foot lower below driver carpet...
I think you'll find 2 more posts there.

Anyways this simple maintenance is going to prevent further weird troubles... we don't need.

At this time, we'll knowingly leave alone the firewall ECU post found in post-lift cars and very likely pre-lift as well (double check non E-Klass chassis).
I have not done this particular one yet myself... go ahead if you want to (remove wiper gear, plastic covers,...) to reach down the firewall face.

> ECU/F-SAM GND Posts:
Footwell posts cover the power circuits.
Firewall powers the ECU logic section (*)

*: save the time now. I don't think this one is bad yet.


Meaning...
-- finish the driver side footwell carpet posts.
-- Drive around, scan
-- Later, do passenger side footwell and ESP.

capth00k

Thanks again Cali-Benz driver -- I'll do that ASAP

I just could not get the carpet to come back more - any special tricks to get that carpet to roll back easily? aside from taking drivers seat out lol.

I also saw from your previous 'inspecting & cleaning ground points' there are plenty of more ground points I'll tackle soon (trunk, behind the battery tray on firewall, inside DS wheel well ) ...

CaliBenzDriver

Now, you've seen the light !!
We're happy you have proactively made your car better.

One word of caution is to focus on fixing current problem only.
Else if anything gets weird, you won't know what may be involved from having pocked all over.

These cars are heavily inter networked... the MB trunk camera can easily screw the front radars.
Let's say, it's not all smooooth.

Try to proceed by sections... right now, we are dealing with the GND of ECU/SAM/ESP.


FYI quickie.... :
> ECU and F-SAM are both best in class Bosch computers where Front-SAM is essentially the muscle man of the ECU to switch power to circuits.

> Shortcut: It's faster to just clean known-bad GND posts than to reliably measure odd conditions.

> Having reliable power is non-negociable for computers. That includes clean GND and soldered connections in modules where chaos has no place.

capth00k

Ok, I will do the grounds behind the carpet next then instead of poking around . Any suggestions on the carpet?

CaliBenzDriver

Yes: PULL HARDER !!!
and remove threshold plastic cover to further fold back the side. The underlayer molded foam is not easy to bend... just no cutting blade.


​​​​​​

capth00k

lol - Oh okay, so u mean the door sill plastic / sill protector ? popped the side panel but not the long plastic sill plate last time. Thanks again

capth00k

Thanks again for all your help CaliBenzDriver. I could not roll the carpet past the brake pedal - maybe i am missing something, but it got stuck right there no matter what I did so I propped it up on one side to get to the ground connector (see pics). I could not find another ground connection ; looked pretty hard but im sure its up under the carpet where I could not get to it -- or was half this ground harness supposed to be on the other post above it?? this is just the way it was when I pulled up the carpet - does seem like a lot of connections to be sharing the same ground post.


location of the ground under driver's side carpet (DS footwell)

CaliBenzDriver

Excellent, mate!
I think this should restore joy for your ECU to control APP.


available screw post opportunity !!

Do you see how screw A is unused ?
Do you see the different wire sizes ?

I moved both skinny wires (#1; #4) together over to the A post after cleaning it.

Skinny wires are logic reference GND (#1; #4)
Thicker gauge are power GND (#2; #3)
a big no-no together, specially with an unused post right there

capth00k

ok, thanks!! i'll get in there again and move skinny wires over to the 'A' post. Was this a factory thing that they over looked? .. odd to bundle that many together instead of use the other ground point. Also noted paint on the bolts (as you have previously) - used a cordless dremel tool with wire wheel to get the ground post clean and the nut

CaliBenzDriver

ECU + F-SAM GND... Logic mixed with Power ​​​​​​

Mixing the ECU logic reference with high power on a factory-painted post is a pretty good way to create ALT VOLTAGE YOYO from unstable skewed reference.

I confirm no longer having the ridiculous yoyo deep drain while driving, yet I don't count this evidence as a 100% solid proof.

capth00k

Thanks CaliBenzDriver that makes sense ; you're way over my head but I can paint a picture based on your previous 'inspecting & cleaning ground points' post (here for future forum lurking reference : Inspecting & Cleaning Ground Points )

CaliBenzDriver

The location of these GND makes these 3x posts super important critical for both the ECU + F-SAM to seek GND from.
These 2 VIP Modules are the car network backbone.
These GND should be gold-plated or simply separated!

Without GND there's no +12V potential, the so called circuit 30, 30G, 15... in German DIN standards that's how ECU can see your "pedal shorted to positive 12Volts" because it has no GND to pull down the open circuit voltage.

The test drive results will be clear shortly - Let's hope it's all good for ya.
​​​​​​✌️

+++++ Carefully floating Reference :


Biased Reference potential skews voltage control

> Biased Reference:
ECU thinks it is measuring 14Volts
when in fact the GND Reference occurs a penalty from drop-voltage caused by loading the poor GND connection.
So the floating GND penalty gets deducted from normal target voltage.

> Low Float voltage sinks COM's:
- Now imagine when the ECU is regulating for the float voltage of 12.6V...

- From that value we need to substract the voltage-drop in the Ref. circuit.

- That drop depends on the load through the poor connection.

- The outcome is we get 0.5V or 1.0V or 1.5V substracted from the 12.6V based on the loss in GND post.
That's 12.1V, 11.6V.... according to Ref. GND drop

> 1300.Watts batt killer :
When the poorly controlled ALT voltage swings up/down, the battery sees 90.Amps extreme "charge current" based on the voltage and its state of discharge.
That's over 1,300.Watts of power cooking batterries (14.9V x 90A = 1,340W)

Normal voltage swings are slow,
Large swings are not frequent and the battery is nearly 100% charged. Meaning we see temporary 5A currents until target voltage is established.


++++++ MB accolades : 👏
I have something else besides the "No-Yoyo" battery killer... I've got the all new "No-Oil-Flashing!".

Its quite a noticeable difference compared to what it has been since factory new.
My factory ordered custom-built lemon with useless extended warranty coverage car is coming back from far.

Instead of burning through a lot of its crankase oil flashed into the intake, the engine stop drinking its own oil. That sudden improvement was shockingly unexpected for me.

Many things witness the engine is not as hot as it used to run...

• No oily smell from intake swamp,
• the exhaust lines are not creaking,
• the rad fan not spinning so much,
• the leaky coolant smell is gone,
• the warmed engine crank is extra short ("Vro-om")

1- The engine oil no longer gets low between service.

2- M276 no longer smell like burning oil in my garage when I park in.

3- The loud piezo injectors TIC-TIC now switches to a TOC-TOC couple minutes after getting into closed loop (heated Lambda, T-Stat, ...)

4- The idle is very much better captured, like a smooth huuuum instead of a higher rpm with ups/downs.
Seemless tranny shifts and torkyier V6-3.5NA below 2,500rpm. More nimble accelerator pedal, no need to squeeze a more solid gas pedal so much.

All of this fine experience is new to me, 1st owner. This car was an overpriced opportunity to meet MBWorld heroes plagued by MB struggles.

No codes!! All well concealed under the radar... so I have almost no clue hard evidence besides what I've taken the time to expose.

In other words if the engine on your low mileage M276/8 consumes OIL and unmistakably smells OIL in combination with only a single tone of injectors like Tic-tic but never transfers to Toc-toc, then consider your ECU proven responsible, not the aluminum/steel engine assembly, not VVT.
​​​​​

S-Prihadi

Sweet.............