I have a 2007 ML 320 CDI that served me faithfully for 18 years. December 21, 22 we had very cold weather in Toronto and while driving for an hour the red battery sign with exclamation mark, beeping and flashing happened. It happened again in January, another cold day but short drive and next morning I also got the message ABS un-operative. When it happened, I turned off the heat and it stopped after a few minutes. The battery is new. I looked at voltage and charging on MB system and everything normal. My mechanic scanned and said that there is something going on the CANBUS system on the vehicle, which is producing many many fault codes in multiple modules, there is a deep electrical issue happening somewhere on the vehicle. My knowledge is limited. I would appreciate your advice. Should I take the car to an electrician instead of a mechanic ?

I took my car to another mechanic with electrical knowledge. It seems the reason for these issues is the auxiliary battery that I don't remember replacing in 18 years.

I had my auxiliary battery replaced but still got the message ABS ESP inoperative while driving after a few days.
It was gone after I made a stop do do some quick shopping and it did not come back. Any suggestions please!

Some codes require multiple starts of your car after you clear the codes (or source of the problem) before they go away. I can't remember exactly what the number is, but recall 3 starts (or something similar) before it resets itself. The ABS/ESP fault after a flat battery or insufficient voltage is very common as these models are very sensitive to even a small drop in voltage.

Thanks a lot, you are right it is gone quickly.
I got again the annoying red battery sign with exclamation mark, beeping and flashing while driving in cold weather for more than half hour. I stopped heat and did some shopping everything normal.

Wont hurt to have your battery, alternator Checked for proper voltage as well as the clutch on the alternator pulley as well as the serpentine belt. The red warning should have gone off immediately

Check your alternator and battery. Here is how.

Not running battery should be at 12V. When you start it it should jump to 14V.

Thanks for advice. I did check and they are ok but the mechanic said that I have a short wire in the alternator and from time to time this will give the message. As per him cannot be repaired just replaced for $1700. Is that true ?

genuine mercedes alternator $400 plus postage and labour.

https://www.fcpeuro.com/Mercedes~Ben...&b=11&d=922&v=

Thanks so much for all your advice. I started to wonder about this new mechanic that I started working with recently. I read that the alternator can be replaced in 1-2 hours and he is asking for labor $1300 ?!!! I guess it is time to look for others, even the dealer cannot be so expensive.

I don't know if the 320 CDI alternator is different than the M272 350 & M273 550 engines. But the alternator for those two is just 4 bolts. 1-2 hours tops. In the GTA they charge $120/hr max. So do the math.

On the NAPA Canada website for my 550 I can get the alternator for $450-$550.

Buy the part yourself (use genuine!!!!) and have a mechanic install it for you. Call around, some shops don't accept customer supplied parts.

Labor is 1.5 hours. Here in the USA, I got a quote from yourmechanic.com and parts and labor came to $701. (it's like an uber site for mechanics)

$400 for the part, $272 labor (plus tax)

Thanks my friends, the conclusion after this quote and having the auxiliary battery replaced without checking that old one was ok is quite clear. Honest people are hard to find these days!
I wish somebody can be a good doctor and get the right diagnosis for my car trouble because it happened again while I was driving to my dentist with a scanner hooked on. I drove half hour, stopped 1 hour and drive again half hour when it started beeping and flashing the off market Navigation system, followed by flashing climate control, tried to turn off, still on, tried again until it happened, red exclamation mark and red battery flashing, DSR inoperative, no signal. I stopped the car, engine on, scanner on, no faulty codes, no message on MB display, but locks not working either and the car was like dead. I plugged the scanner, waited for 5' and tried again, everything normal, no red battery, no messages. I measured battery home and it shows voltage 12.74V, State of charge 100%, Life (SOH) 9.7% (always wrong this one measured from the posts not directly). I expected the battery to be dead but it was not, somehow I have a short, I was thinking the climate control or navigation system or even a wire inside the alternator as the mechanic said. It is driving me crazy, I think I will need to take it to Benz dealer but these guys are not honest either. Any suggestions please? Thanks in advance!

Sounds like you don't have anyone to trust which is frustrating. You'll need to do your own homework no matter what to be satisfied. I know that feeling.

The red battery message is almost always a charging issue and the problems you're describing appear to be intermittent. Does your scan tool show you alternator output on some form - at least then you can monitor it to see if your mechanic is correct?

I had the scanner connected during recent drive, maybe this is the reason my car got dead for a few minutes but when looking at codes I found U0423 Generic Invalid Data Received from Instrument Panel Cluster Control Module that can be lots of things and it seems requires specialized scanning by dealer that I try to avoid at any cost. The other code that I found related to my previous ABS message is 5104 - L6/1 (left Front Speed Sensor): Clean Multipole Ring and Replace if necessary. I wish I knew how to do some things on my own because as I see for everything you get charged $200 per hour.

Go to Sam's Garage in Markham. They aren't cheap. But they definitely know their MB's.

Also try asking on MB True North on Facebook. They might have a recommendation of where to go.

This is getting very strange as I was driving today for shopping around 20 kms with 2 stops. On the way back traffic was jammed due to construction and I start hearing beeps from the parking sensor, red battery sign, turn signal, wipers, locks not working except mine and an extra noise like ventilation under the hood. I stopped, removed my key, the noise was still there like engine still running, lifted the hood and finally stopped after a minute. I checked the battery from there it showed state of charge 86%, voltage 12.51V. I scanned after I turned off the engine and it just showed code 2013-000 the fault code is not found in the database. Looking on the net I found A DTC code 2013 000 typically indicates "no diagnostics trouble codes". I re-started the car after 5 minutes, driving home with none of the things before, just check engine light and DTC 2013-000.Any idea?

Problem solved: the culprit was the off market Navigation systems made in China that I used for the last 4 years after the original one died. I noticed some flashing or garbled screen in the past few months and I tested shutting down but not unplugging. Any electronic connected to the car can screw up everything! Thanks for all your comments and great support!