Alrighty, here goes nothing. I'll try and keep it short. I bought an 2006 ML500 a few months ago in December. Past few weeks has been acting up. First I started getting the ESP light which would come and go. Then then ABS and triangle "!" light. The ESP quit coming on. Now the ABS and "!" stays on all the time... but the main issue happened last week when the fuel pump felt like it was about to give out on way to airport, about hour and half from the house. That caused CEL to come on. I took it to a mechanic first thing when I got back in town. He couldn't figure out what was wrong so i took it home. 111 codes. Most cleared out and CEL was gone when I started to drive it. However, about an hour into to my trip home I pulled off to a gas station. When I started it back up the CEL came back on and it did another slight hesitation on hte way home but nothing major. I've only driven it once to the store since and the CEL and ABS are still on but no hesitation in the fuel delivery. I have a couple of questions. Could this be the front or rear SAM issues? Is SAM the same as ECU? If not, where in the f!@# is the ECU or PCU or whatever it is called in the ML500? I'm very very confused about the systems in this benz.
Posted are pics when he first diagnosed and after he cleared...

 

The codes after he cleared the first group. He said this was it and couldn't get the CEL to come back on. It was only when I had driven it for about an hour that it came back on. So I assume there are ton more codes after that happened to.

 

EDIT is in italics.
Post in the sub-forum for your vehicle for the best shot at obtaining assistance.
Stored codes: I don't care about them; they just inform me there was a problem in the past but it is not there now. I've disconnected the CANBUS connectors at a junction point while troubleshooting then reconnected them while the door was open and the circuits were active. My diagnostic system indicated stored failure codes on every module in the car. Cleared codes and all was good.
Current codes: those are the ones you should be concerned with. Code S170 is what is I would say is killing your ESP; without knowing what the angle of the steering wheel is (which way is it turned and how much and how does that compare to what the other sensors such as wheel speeds and yaw rate are reporting) the computer goes into fail-safe mode. Motor electronics codes (apparently oxygen sensors) are triggering the Malfunction Indicator Light; although cleared, if it reappears and the codes show the same, start with the sensors. A low voltage event triggered the transmission control module which signaled the Motor Electronics there was a potential problem causing yet another module to go into fail-safe mode. That could be a marginal battery or an intermittent connection be it power or ground. If you pull power to the car, you must turn the steering wheel lock-to-lock to reset the steering angle sensor the first time you start the car. If you have to jump start your car, do NOT have the key fob in the ignition switch when connecting the jumper cables. The voltage spikes caused by arcing can potentially damage or destroy electronic modules as well as blow fuses. Connect jumper cables, then insert key fob.
Clear all stored codes. Drive the car and re-check for current codes. Analyze and repair from there. Generally, the lower the number of the code the more important it will be. I find that starting with the most important code will clear several other "current" codes caused by the most important code.
You must have a proper diagnostic system for your vehicle; it is a distributed digital control system connected via CANBUS and carried around by an internal combustion engine.
Search (Advanced in upper right is best). Read. Read some more. Do not throw money and parts at the car until you obtain a proper diagnostic system that WILL work with your Mercedes. I have a STAR C4 system via BenzNinja but those are not particularly cheap. Autel makes some decent systems that will work on Mercedes. Research and ask.
Again, post in the appropriate sub-forum. If nothing there, try the technical sub-forum. If nothing there, start looking for the "gear heads" who you will find in the AMG sub-forums.
Good luck to you.

 

moved to W164 forum...

 

I'd start with your battery and charging system. Make sure they're good to go. Even a small drop in power can trigger faults and given youve got so many, it could point to the one system that connects everything - power. I had another MB that sat for years. I jump started it but battery was dead. Every possible code and light came up.

ECU is not the same as front and rear SAM. Doesnt sound like a SAM issue at this point.

 

I agree, a fresh battery for starters. Even if its on loan just to try it out. New battery, clear codes, take her for a run, rescan. You may find that some of them have magically disappeared. These old girls get a bit antsy when the battery starts getting weak.

 

Have your alternator checked. Dont underestimate how even with a good battery that it can cause dramas. My approach is to work out what works first, then you'll see what doesn't. Good luck

 

If it already has an AGM / glass mat battery, you would be well-served to get a charger which can bring it back up well and safely, for example:
https://www.amazon.com/CTEK-40-206-5.../dp/B00CD44RQO
I really like this one, because it is also great on reconditioning conventional batteries that have been discharged flat.

As others have said, a low voltage situation will drive MB cars absolutely off the cliff throwing codes all over. (My car has 35 computer modules in it, for example)
And, as of December last year any car still using the 3G cell network lost all connectivity for Tele Aid (Mercedes' OnStar service).
So the radio turns the heat up trying to connect to - nothing, and stays active even when car is asleep/locked, for security purposes. (?)
At least, I had to start putting mine on charger every night if I wasn't driving it daily, since around Christmas.

 

Thanks to everyone for your responses.
So would a faulty charging system/battery possibly cause that symptom where it felt like my fuel pump was giving out and triggered the CEL?
I'll be checking that battery at some point this week. I noticed yesterday it's a refurbish from the "buy here" place with their name on it HAha.. Took me longer than I want to admit to find the battery.
Please speak in lay terms. I know next to nothing unless I've had to fix a particular prob via youtube. Where is the ECU on this thing? TIA

 

Fuel pump can be easily checked by connecting a pressure gauge to the schraeder valve on the fuel rail (looks like a bicycle tube valve). I do not know the specs on your vehicle but it should be easy enough to look up on the internet.
When the ME (motor electronics) goes into "fail-safe" or "limp-home" mode, the computer will switch to using a fixed map for fuel and timing causing a significant loss in power. Like the others said, check battery and alternator, then check fuel pressure. Then clear codes, drive, and see what remains. Focus on those. It can be intimidating at first but after awhile, you'll be in here advising newbies.

 

Its very hard to know and can't be discounted. A charging system that produces less than optimal voltage can do so either all the time, or some of the time. But you can't think of your car's battery and charging system like they're AAAs which as they run down, keep items working but at a less than optimal level. With all the computer modules a temporary drop in voltage, say to 70% of the optimal/required voltage, doesn't mean things will run at 70% of their capacity. They may switch off altogether (even if just for a few seconds) as they've passed a threshold minimum voltage required. That's why with diagnosis, the starting point is almost always to check the battery and alternator. No point in replacing a part only to find it was the power supply to it that caused the problem. Sorry this doesnt answer your question specifically but I've seen people replace good parts with new ones when the problem was elsewhere.

 

Thought I could upload a short vid. Guess not...
I put a meter on it. It reads at around 12.27 dropped to 10.37 when starting and held around 14.15. Should it drop to low 10's like that when starting? Should I go ahead start with a new battery and then go from there? I had the fuel pump tested at a garage already. In fact, it cost me $200 for the guy to tell me it wasn't the fuel pump. After replacing the battery should take it back to the garage and get it on another diagnostic for $100? Or should I just go purchase a better obdii? I had one from Walmart that was a waste of money. Suggestions for a cheaper model that'll get me what I need?

 

Voltage always drops when you put a load on the battery before the alternator starts charging. Many say 10.5v is about the minimum but whose to say 10.37 isnt about right? From the numbers you've provided, it all looks to be OK. To check your alternator, start it and put it under load - turn on demister, head lights and a/c and if it holds at approx 14.1v then you know your alternator is OK.

Invest in a better scan tool. Autels have shown to be good value. It'll pay itself off very quickly and worth the added expense. Mine stays in my car.

There's heaps of YouTube videos on testing batteries.

 

Here are few things I've seen, and how I deal/cope with mine, FWIW.

I use the CTEK charger I mentioned earlier, it comes with 2 unpluggable tails - one has clamps the other has eyes for attaching semi-permanently to a battery.
Since the under-the seat batteries are inconvenient to access, I leave the bolt-on tail attached and available to either charge, or probe the battery voltage directly with a meter.
I do see a little drop between direct measurement and the displayed voltage in the dash menu (scroll to odometer reading with key in 1st ON position, then hit the reset button 3 times...).

If the voltage is below 12 volts at rest before cranking, or especially if down near 10 volts while cranking the motor won't spin fast enough to start.
(I think minimum is supposed to be 200 RPM)
I would guess cranking a 5.5 V8 gas motor draws about the same as a 3.0 diesel.
If the voltage goes below 10V while cranking (from memory), the ECU will intervene, stopping the cranking signal to protect, from discharging the battery so far it gets damaged.

Looking at voltage while running, understand that many platforms have a smart voltage regulator, meant to 1) save fuel and 2) not overcharge the (more expensive AGM) battery.
On my car, the alternator type is 'LIN-bus' where the ECU monitors the state of charge of the battery (according to the alternator?), load, road speed, etc. and has the ability (back over the LIN-bus) to tell the voltage regulator to cool it/take a break.
Often I will see readings of 13.7-13.9 on the dash after a start (maybe a little lower if starting was difficult).
As I drive I can see the indicated voltage creep back up, ultimately to 14.0-14.1, and flickering back and for on these final values.
Any changes in load (turning radio/amplifier or AC or headlights) will cause perhaps a short dip before the regulator adjusts.

Leaving it on the voltage display on a longer trip, I can see the voltage creep back down for periods, then come back up.
But not below about 13.6 running down the road.

I've also watched the dash display after getting where I'm going.
While the harness voltage will continue to read 13+ volts at rest when you turn key to ACC position, it will drift down according to whatever accessories you have on.
The fully charged, at rest voltage for a nominal 12V battery is 12.6 volts, and if you continue watching the dash display (and it's not really cold outside!) it will return to this.
https://batteryguy.com/kb/knowledge-...minal-voltage/