Your ESP module might be damaged. OBD2 reader won't show a code for that. You need to get your car checked with a STAR system. Dealer isn't the only option but is the most expensive option for sure. An Indy shop that deals with Mercedes will be able to read any codes you have with their STAR system.

 

P0620 is a diagnostic trouble code (DTC) for " Generator Control Circuit Malfunction".

I'm sure this code is STORED and not CURRENT and it has to do with your Alternator not working previously. It has nothing to do with the ESP. You should of never drove the car with a bad Alternator, I'm afraid you might of damaged the ESP control unit. When this stops working, so does the ABS. But the ABS system should be fine.

Did you get them to clear the code ? If not, you can try that first.

 

Thanks for the quick response 2008CL6. Since the code is stored, I have a glimmer of hope that I didn't burn anything up.

I have not had anyone reset or otherwise clear the code yet. That is my next step. We have a pretty good Indy shop here that I can take it to.

I just finished testing the trunk fuses. All good except the one for the center console power outlet. That outlet has been out for a while now, so that wasn't the problem.

In looking at the fuse diagram, there are several "prefuses" in the engine compartment pertaining to the alternator, electrohydraulic power steering, ESP control unit, and regenerative braking system control. Attached is the diagram. I can't test those without pulling out the box and opening it up. I'm guessing if getting the code cleared doesn't do the trick, the culprit is in this fuse box.

 

No worries, this is what this forum is for, to help each other as much as we can and as quick as possible.

The fact this code is STORED is not a good thing because basically it don't matter anymore it is only there to show there used to be a problem. There is very little chance it will do anything to clear the code, but you should try it since it cost nothing.

You should check all those fuses and relays next. Yes it could be possible one just blew. Let's all pray for you this is the case because the ESP control unit is expensive even used.

 

To clear the code you just need an OBD2 reader, no need to go to any shop. Take it to the auto parts store they should be able to clear it.

 

The problem you describe is obviously worse than just the warning lights, but just in case... you could try turning the front wheel stop to stop - perhaps as many as 3 times - to clear them. That won't cure an electronics malfunction like the pre-fuse you discussed, or a control unit, a wheel speed or steering angle sensor, but I'd try it anyway.

 

Thanks, Warren. I have tried turning the steering wheel stop to stop a few times, but it has no impact. My recollection is that this process re-calibrates the steering wheel level sensor and that the ABS/ESP indicator is on as soon as the car is started when the sensor is out of calibration. When I start my car, however, there are no warning lights illuminated, so I don't think that process is going to work in this case. It's only when I accelerate that the warning lights come on and the car appears to go into some mode that disables (or limits) the power steering. I'm thinking that mode may even intentionally disable the ABS/ESP to protect it.

After much research, I have learned that loss of ABS/ESP is a symptom of a failing battery. If the battery voltage gets too low, it will shut down these items before the battery goes completely dead. In my case, however, the battery wasn't too low when the indicators came on. The battery was actually in an overcharged state, which gives me concern that I may have burned something up (fuse or module).

I've also found that the "ABS/ESP inoperable" light can be illuminated due to a faulty wheel speed sensor. This is definitely a possibility since the symptoms are generally that it illuminates upon acceleration, as is the case with my car. However, this will also throw a fault code with an OBD reader and that's not occurring with my car.

I'm thinking that 1) something needs to be reset with Star Diagnostics; 2) a fuse is blown; or 3) the ESP/ABS module got fried. My bet is door #2, but I'm hoping for door #1.

 

You should hope for #2 because that's an easy fix, just replace the fuse. #1 means you have to spend money to find out and that might not even be it. Start by checking the fuses and relays and let us know what you come up with.

 

Soo, which battery did you replace? If it is just the starter battery under the hood (bonnet), then you likely need to replace your consumer battery as well, the one between the trunk and the rear seat.

The logic being, your alternator was not charging correctly and so the batteries were being drained every time you used the car. When I got an ABS/BAS error last fall I connected to the SDS and found that the front battery was 12.7VDC at rest (engine stopped), while the rear was 10.3VDC. That Consumer battery is power for all the gizmos on the car.

I read through your posts a couple of times but did not see that you replaced the Consumer battery, forgive me if I missed it.

 

Yes he is right, you need to check the second battery you haven't replaced and see if it is good. If not it could cause this problem too.

 

There is also a 3rd small AUX battery which I have heard can cause these problems too if it's bad. The first step for you is too check the fuses/relays. Then check the second battery you haven't replaced yet. And third would be this small AUX battery.

 

DLAFever,

I should have stated, the starter battery was fine. It was the consumer battery in the trunk that I replaced. It got down to about 11.6 volts before I replaced it.

I haven't checked the starter battery again, though, since I replaced the new battery & the alternator. Might as well test that again just to make sure.

Thanks.

 

2008CL6,

I have already tested all of the accessible fuses in the following 5 locations: under the hood passenger side (visible fuses only), under the hood driver's side, driver's side door, passenger side door, and trunk. They are all good (I did have to replace one 15Amp fuse for my center console power outlet).

One of the fuses that I thought may be blown, however, is what they are referring to as a "prefuse". The prefuses are located in the engine compartment fuse box on the passenger side. To access the prefuses, I would need to pull the whole fuse box out of the car, pry the box open, then test the prefuses. Attached is an image of the prefuse box (from an ebay ad - not my car).

When typing this up, though, I looked closer at what the enclosed prefuses are for:
F2) Alternator - 400Amp
F3) Glow time output stage (what???) & Electorhydraulic power steering (150 Amp)
F5) AAC with integrated control additional fan motor (100Amp)
F6) Front SAM control unit with fuse and relay module (150Amp)
I do not believe that any of these will be the problem.

Where I was thrown off was, on the same diagram, the following fuses are shown:
F7) ESP Control Unit (40Amp)
F8) Regenerative Braking System (25Amp)
I thought these were also prefuses inside the box, but they are actually outside the box. I've already tested them and they are fine.

Also, to my knowledge, the 2007 S550 doesn't have a 3rd Aux battery. I could be wrong about that, but I've never heard of one.

Next, I'm going to take my car to the auto parts store and have them reset the code. If that doesn't fix the problem, then I'll take it to the Indy shop (unless someone else has any thoughts/ideas???).

Thanks all!

 

Just tested the starter battery. 12.97 volts, so it's fine.

 

The pre-facelift cars have the three battery system, Starter, Consumer and Backup (settings) battery behind the dash on the driver's side.

Glad to be corrected on the Consumer battery! Wish I lived closer, we could hook up the SDS and see what's shaking with your car.

 

You do have a 3rd very small AUX battery, look here :

https://www.benzworld.org/forums/w2...ms/w221-s-class/2981042-2007-w221-3rd-small-backup-battery.html#/topics/2981042

 

Okay, thanks for the info on the aux battery! I'll check that out tomorrow.

 

Me too, DLAFever! I could help you get a lot of use out of that SDS!

 

Does your car have variable power steering? Think Mercedes calls it SPS, speed sensitive steering.

Overcharging damages the solenoid in the SPS, which operates at a strict 12.5 to 14.8 volts. Anymore ends up burning the solenoid. Bad alternator overvolting past 15v will kill it.

Get a Autel/snap on/Launch/SDS on that car and check the ESP and steering column and power steering unit for any codes.

 

This is what I think most likely happened. The over voltage fried the ESP control unit.

If ever the red battery light comes on, you should stop driving the car immediately and get it checked.

 

Deplore - Thanks for the post. No variable power steering on my car as far as I know. Had it on my BMW 545 (and loved it) but I've never seen any indication that this car has it.

2008CL6 - You could be right. But, I would think that the fuse would have been more likely to blow out prior to damaging the control unit.

I will get the codes reset today and let you guys know the results.

 

Codes were reset just now using an EthosEdge Snap-On Scanner. It did not correct the problem, but did show me the following codes:
5964 - Component A7/3 (Traction system hydraulic unit) has an internal fault
5944 - Control unit N47 - 5(ESP control module), internal fault

The highlighted code on the scanner is the first code (5964).

I found this related thread on the forum:
https://www.benzworld.org/forums/w221-s-class/2906682-abs-esp-errors-how-i-resolved.html

The symptoms are exactly what I'm experiencing with respect to the indicator lights coming on after acceleration. I don't have STAR/XENTRY. Is there anyway to do the "Road Test" described in the aforementioned thread (which may or may not work in my situation) without SDS?

 

Road test won't fix the internal fault error. Looks like you'll have to replace both abs module and esp module after all.

 

Why the ABS module ? There is no codes for that. You should replace the ESP control unit only at first and see if the ABS will be fixed first before replacing that too.

 

Because:

5964 - Component A7/3 (Traction system hydraulic unit) has an internal fault
5944 - Control unit N47 - 5(ESP control module), internal fault

Traction system hydraulic unit....that's the ABS unit.

Road test will give a different code. It will show on the cluster as:

(1) ESP unavailable Diagn./Rig test
(2) BAS unavailable Diagn. Rig test..

and under the codes it will specifically say "ROAD TEST".

Internal failure and road test are two different things.

I would be surprised if this does it, but I doubt it.

 

EasyPhil had the same codes showing internal fault but was able to fix the same problems just by doing the " road test ". You should try doing that first before you start replacing any modules.

 

It looks like you just need to recalibrate the ESP control unit like EasyPhil did