Car is a 2007 E550 4matic.

Over the last few weeks I've been getting a random "esp inoperative" warning. It doesn't come on every time I drive the car and it's usually off after restart.

Last night, I got a "right side low beam out". Car has an aftermarket hid kit that's been installed for about a year or so. I replaced the ballast with a spare this morning and it worked.

Took a 300 mile trip today. After about 150 miles the esp inop message popped up. Didn't think much of it. Drove another hour and got a warning that the right side low beam was out again. Shortly after I stopped for gas and upon restarting car, I got all kinds of errors. Esp, abs, srs, speedtronic, etc.

I turned the car off and went inside the store at the gas station. When I got back in the car, it wouldn't start. Nothing happened when turning key. No crank etc. after 5-10 mins it did start. I headed back on the road, and noticed it wasn't shifting right. From a stop it was revving a lot to get going. All the warning lights were still on, the speedometer needle was bouncing around and the nav was (and still) stuck about 50 miles back from where I am now. Once on the highway it ran fine.

I was able to get my bt obd2 scanner and torque working at one point but it no longer does. It showed 14 codes at that time but I wasn't able to jot them down.

At this point, the car is home. It starts every time but all the same warnings flash and as soon as it starts, the cooling fan is on full blast and won't go off. At one point I also got a red battery icon. The battery is about 6 months old. It's an AGM from advanced auto. I've since put it on a charger and fully charged it and all the same issues persist.

I thought this was an alternator or voltage regulator but since it's charged now and having the same problem I'm not sure. Maybe an ecu issue but hoping someone has some ideas on how to proceed before towing to dealer.

Thanks!

 

Check the voltage when the car is running. You can switch to the voltage display by switching the cluster to temperature and then hitting the odometer reset button three times with the ignition on, but without the engine running. Then once you start it, it should tell you the voltage. All those errors sound like a low voltage problem. You also have a battery control module. Search the old threads about that one. Usually voltage problems are either alternator, voltage regulator or battery control module. Your esp inoperative is a separate problem. Probably the steering angle sensor. If you search the threads you'll find that too, there's also a youtube video on how to replace it. You should get a real scanner that can do MB codes. I like to use a cheap x431 Launch easydiag plus. It's about $50 on eBay. Make sure you get the plus version which comes with software for 2 vehicle manufacturer, there are cheaper versions, but it doesn't come with the 2 free vehicle manufacturer software and it's another $50 to add a vehicle manufacturer. Worked to tell me I had a bad steering angle sensor (it can also be a few other things like a wheel speed sensor, brake light switch or yaw sensor).

 

I should have mentioned voltage while off is 12.8. When starting car it goes to 13.3 and slowly moves up to about 13.8. This is as checked with a multimeter across the battery terminals.

I searched for the battery control module from a parts standpoint and didn't find anything for w211s past 2006. Did they do away with it when they dropped the 2nd battery?

 

Batteries need to be check under the load as static voltage is not telling much, unless the battery is dead.
Turn all the headlights, rear defroster and blower and then read the battery.
13.3 climbing to 13.8V alternator voltage indicate some problems as well. How old are alternator brushes?

 

The alternator is original. I swapped out the battery with my truck this morning to make sure it wasn't something like a shorted cell causing voltage drops. No difference. I put my normal (fully charged) battery back in and went for a test drive.

Only three errors are currently displayed. "Pre safe inoperative", "SRS malfunction", and "speedtronic malfunction". Aside from that, the cooling fan is still on full blast, there appears to be no or very little power steering, and the gear indicator lights on cluster are not showing. The comfort/sport indicator is also blank right now. It appears to be shifting through all the gears and drivable enough to get it to a shop or dealer right now.

 

Oh yeah, the battery control module always gets mentioned but I guess I'm not sure what year it went away in. Anyway, the voltage regulator is also built into the alternator. Some just replace the voltage regulator instead of the entire alternator. If you're at idle 13.8 might be ok, should go up to 14.4-14.5 volts once you're driving. Get the voltage to display on the dash and take it to an auto parts places and have the charging system checked, they'll be able to tell you if you have a bad alternator. If the battery is fully charged, you should still be ok driving it so it might be some other problem. I think the system doesn't start to shut down various systems til the voltage drops below 11 which could be happening under load.

 

Yes... Lots of electronics, servo motors, sensors and control boards with large scale IC chips to fail.

I knew this going into the purchase

Best place to start is make sure the electrical charging system has the capacity to run all those electronics. This includes using the correct size "AGM only" batteries that the vehicle was designed to run and making sure the alternator's voltage regulator is functioning correctly. I replaced all of these items and many electrical gremlins went away.

 

Car ended up going to the dealer. They're telling me the central gateway is/was wet and showing signs of corrosion and requires replacing. Will be a few days before that's done. They don't know if that is everything it will need at this point but they tell me they can't diagnose further until that is replaced.. Looking at about $850 for this repair.

 

thats why theyr called the dealer, stealer

 

You bet. Most likely all this guy needed was a Bosch voltage regulator, $45 at PartsGeek, and a little handiness to swap it on the existing alternator, which you don't even have to remove to change the voltage regulator.

Dude -- if you're bringing it to the dealer for service, the car will become rapidly unaffordable.

 

It's well beyond a voltage regulator. The multiple system errors have everything pretty much disabled from suspension control to abs to speedtronic to srs and more. Aside from that, the gear indicator and comfort/sport indicators on the dash are blank and the obd port is inoperable even when hooked up to SDS. While this part is a simple swap, I'm fairly certain no one other than the dealer is going to be able to program it for me.

 

These symptoms are similar to what I had when my front SAM died. Don't go throwing parts at this get it diagnosed correctly you'll save $$$ in the long run.

 

Today you have whole variety of scanners who will do it for $200 or even less.
When you have multiple possibilities, you always start with simplest and cheapest issue.
$60 for Voltage regulator and 1-2 hr of DIY is sure cheap and easy enough.
But when you take it to stealers, it will make about $1600 for alternator replacement and open whole chain of events.

 

It went there for diagnostic since my friends shop was unable to read from OBD with snap-on (normally he can). Dealer was unable to connect with SDS. When they told me it was the CG, I decided to let them do this repair. If they'd told me it was an alternator and voltage regulator, I'd have had them replaced elsewhere or done it myself. When I brought it to the dealer, I was certain that replacing either of those items wasn't going to restore all the cars systems or dash readouts or OBD. My guess was a bad alt or VR took out the ECU.