Hello everyone,

I have some electrical issues with my ML500 and would appreciate any suggestion to help solve the problem.
Below is the list of the issues:
-Front Right Turn Signal not working (I checked the bulb and the fuses and everything is fine, removed the front passenger seat and checked the SAM module connections and they seems to be fine)
-Battery icon with the "Visit Workshop" message on the screen (I've checked the secondary battery connection under front passenger seat and all they are fine except one cable that was disconnected from a small box sticking on the side in front of the main battery so I connected it back but it didn't fix the problem and now I have a third message "SRS not functioning")
-Rear doors windows don't work most of time and some times they go down but not up (Checked the fuses and they are ok, I can hear the relays clicking when I push or pull the button and I checked the power motors and they turn without problem when I power them with 12v )
-The light switch does not work at all (headlight are automatically powered can't turn them off only after locking the car)
-Parking lights and also not working.

I am suspecting something wrong with the SAM modules but not sure sine it seems that these problems are related to each other if the fuses and lamps and power motors for the windows are not damaged at all and work when I power them manually.

So any suggestion? thanks.

 

Remove everything in the spare tire area and see if there is any water intrusion.

 

Thank you for the suggestion and the document. I will try today and let you know what I found.

 

Ok I checked the rear sam and still didn't find any sign of water intrusion or corrosion, I checked all the plugs and they seemed all fine.
Any suggestion?

 

You must own your own scanner to check for codes in all modules.

 

Hello!
I have a w169 but seems like we are in the same boat. I just started a thread too and was hoping to get some answers. I also have voltage drop when I put load on the system (ac on, rear windshield heater ecc...). If you find a solution please let me know, and if I find it first I'll let you know. We can exchange e-mails if you want.
Have a great time!

 

Hi.

How is the main battery situation? This car may be shutting down functions if the battery is bad. Can you measure the CCA of the battery?

 

Hi everyone, and thanks for your responses.
Maj. Dundee I have a recently purchased obd2 scanner called Motopower like this one here: I tried several times but it says no fault codes detected in the vehicle which is not making sense for me so I'm thinking about getting the ICARSOFT V2.0 for Mercedes Benz to be able to read the fault codes but I'm open to other suggestions.
The battery is in good shape as it shows 12.7 and after turning engine on it jump to 13.8
I uploaded some pictures of what I could see on the obd scanner and some pics of the rear SAM module. I have one question if someone can help me identify that box in the red circle as I found it disconnected and I don't know what is responsible for. Also if anyone can check the values of the datastream to confirm if they are good or not?
thank you guys for the help.
Tirent2 absolutely we can stay in touch for any update.

 

Can anyone help me identify this plug I found disconnected and no place where to plug it back.

 

Can anyone help me identify this plug I found disconnected and no place where to plug it back.

This vacant connector means that your vehicle does not have the option/feature.

Look at all sides of the conn. for a part #, (sample xxx xxx xx xx) and post it along with your vin#.

 

This connector looks like it's an adaptation. Mercedes usually use connectors with external locks.

 

Clean the corrosion off your SAM with iso alcohol and an old toothbrush.

Get the scanner the Major suggested and scan for codes in all the MB modules. Your generic one can only do the engine and gearbox modules.

 

​​​​​​Hello again!
Small update: I had the car checked with DAS (mercedes) scanner and the guy told me to chenge the alternatore so I'll do that in the next days and let you know if that fixes the problem for me. Since we have almost the same issues it may work for you too. I had the regulator replaced some months ago and he advised me to change the whole alternator to be sure, as the guy previously may have put in the wrong regulator or it may be the alternator's fault.
Have a good day!

 

Hi Tirent2
I checked the front SAM and I think it's the root cause of the issues as you can see in the pictures corrosion damaged some connections, so I went ahead and purchased a used SAM from ebay for 250$ and hope it fixes all the problems. I will post an update when I replace the module.
Tirent2 I suggest before you go ahead and change your alternator to check the voltage after starting your engine I did above, and if the voltage is higher than 13.4v approximatively then I think your alternator is fine.

 

Hello!
That's quite a bit of corrosion and bad contacts! I can Imagine that the isn't working properly. I ca do that, check the SAM but the alternator has to be changed anyway as the guy with the fancy scanner said.
Thank you for the update!
We keep in touch...

 

Question: Do you have any voltage drop with the engine on when putting load to the system(turn on ac, rear windshield heater, high beams, ecc...)?

 

Hello!

Small update: alternator changed, turned everything on while still at the workshop and everything worked normally, no voltage drop with everything turned on. I then took it for a 50km test drive and... I still get voltage drop the same way, under 13.0 v. Since the steering wheel is elecrical I get voltage drop even when I turn it left and right a full turn.
The only problem that is "solved" is the SRS light that furned off after reconnecting everything.
Now I'm thinking about checking the pulleys as I hear a small grinding noise specially when I turn on and off the AC.
I'm about to give up on the car...

For people who may get confused: this is not my thread, I'm just posting what I'm doing on the car since we have the same apparent problems and also people may benefit from reading this in the future.

 

Maj. Dundee I have a recently purchased obd2 scanner called Motopower

You bought the cheaper one and not the one I suggested WHICH READS CODES IN ALL MODULES.

 

Hello Everyone,

Here is the update: I received the front SAM and replaced it and it fixed all of the above issues (turning signal working, parking lights working, read windows working)
only one problem left: SRS red light still on. any suggestion?

 

Get this scanner to read codes.

 

Hello!
Nice to read that you solved most of your problems!!
About SRS light: mine went off when I replaced the alternator, perhaps from disconnecting the battery or from moving the passenger seat the connection made contact I can't say that as I have tried other times to clean the connections and it didn't work... I know this may help a little or not at all but this is how the SRS light went off on my car.

This is helping me a lot to get more focused on the SAM module as we had almost the same issues.
So, thank you and thanks to everybody else who replied here!