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Pete, Mercedes Mechanic
Category: Mercedes
Satisfied Customers: 27884
Experience:  Over 15 years experience as a Mercedes dealer technician
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I own a 06 ml 500, & we have had several issues with random

Customer Question

I own a 06 ml 500, & we have had several issues with random warning lights coming on, interior lights blinking etc. We replaced both batteries ladt week.
Last night we had old battery tested at O'Reilly & they said it was good. About an hr later the car started with warning lights..then Windows wouldn't roll wouldn't shut off and wipers wouldn't work. We pulled over, shut car off, turned it back on, everything working again.
What the hell is going on? We live in Seattle can not drive with no wipers and Windows down!! Plus car not shutting off is super dangerous!!
Submitted: 1 year ago.
Category: Mercedes
Customer: replied 1 year ago.
This isn't the first time this has happened btw. We know about the electric system under passenger seat and not spilling liquid. There is a video on you tube with another ml 500 showing same problem but no diagnosis.
Expert:  Pete replied 1 year ago.

My name is ***** ***** I am a professional here at Just Answer. I noticed that your question had not received a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.

This may be a fault with the electronic ignition switch itself.This is the switch the key inserts into.If this switch is acting up intermittently it will cause all of these faults here and is most common.It will need to be tested and if replacement is needed a dealer will have to replace it as it requires programming/coding after it is replaced.

The other issue is with the front and rear SAM control modules.These can short out/fail internally and cause issues like this as well.Although the electronic ignition switch is most common.

You will need to have fault codes read out of all computers with either a dealers sds machine or a scan tool that will plug in and communicate with all computers in your vehicle to see what codes are set and from there those codes diagnosed to locate and repair the fault.The sds machine or compatible scan tool is also used to observe data and check signals from the electronic ignition switch to make sure it is the cause here.

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service.You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.

Thanks Pete

Customer: replied 1 year ago.
Hi Pete
Thank you for your reply. You were the only response I got so thank you! My husband thought we may need to call in Priest Lmao!!!
So do you work for a dealer? Or an independent shop? Would you have any idea of the cost of the starter switch? And is possible that this could fail and strand us? We have a trip planned this weekend and it seems when we turn it off then turn it back on it works just fine.
Customer: replied 1 year ago.
Started engine brake light was on then lost window controls and wiper function. When we turn the key off and remove from ignition engine runs aproximately twenty seconds then the engine stops. Put key back in restart engine every thing is fine no more issue that night. Just more details...
Expert:  Pete replied 1 year ago.


I used to work at a Mercedes dealer for over 15 years.Now I do my own work as well as work from here to help customers.The cost can vary all depending on the fault occuring here.This sounds more like the electronic ignition switch (EIS) at fault and this in some cases can cost over $700 to have replaced and will have to be programmed by a dealer or authorized Mercedes repair center in order for it to operate after it is replaced.

It is possible at some point it may fail all together and not allow starting or may cause a stall out and can keep from allowing the vehicle to start again.It is hard to say if this will occur for sure though.

I would have this checked into/tested further to be sure this is the cause here.

Let me know if you need anything else here and feel free to rate my help.

Thanks Pete

Customer: replied 1 year ago.
Hi Pete,
Well I have encountered another issue, this has also happened before. I let the car sit for 24 hours, went out to start it and it was like it was dead. The clock was running backwards and wouldn't start. No click, no nothing. But the radio turned on, and the heater. So I shut them all off, hooked it up to the charger and it reads 25%? These are BOTH new batteries??? So can this be something besides an ignition switch or is this maybe a constant electric drain on the battery??
Expert:  Pete replied 1 year ago.

This does sound like low voltage which will cause the electronics to act up like this here.If these are new batteries or a new battery installed this sounds like you have an electrical component draining the battery down.This would need to be tested to see which component is causing this here and requires a multi meter to do this testing as well as the correct wiring diagrams to locate the component on the circuit that has the battery drain at fault.I can post the procedure below on how this is tested but this will require the correct wiring diagram of your model for this here.

I can say I have seen the instrument cluster and the SAM control modules fail internally causing this drain/draw issue needing replaced.

Thanks Pete

Customer: replied 1 year ago.
Can I ask you what is a SAM control? Where is it and do you have a round about estimate on those? Thanks so much!!
Expert:  Pete replied 1 year ago.

SAM stands for signal acquisition module.They control and monitor several electronics inside and outside of the vehicle.

Depending on if and which are at fault this can run around $700 to over $1000 for replacement.They also require programming to be done by a dealer when replaced.

Your welcome,let me know if you need anything else and feel free to rate my help.

Thanks Pete

Customer: replied 1 year ago.
btw in a Mercedes forum I saw this:
Join Date: Feb 2002
Location: Atlanta, GA
Posts: 434
There is a TSB on this:
Mar 11, 2009T-B-54.21/198fRevision: Remedy 3 Added
Model 164.122/172/177/186/822/871/886, 251.122/156/165, Model Year 2008
Battery Discharging - Increased Rest Current in the Rear SAM / CAN Bus Awake
Mode Software in Steering column Module (SCM)My car is a 2006 ML 500 but not sure the model. The car this person was talking about was a 2002 ML500. Do any of these TSB model numbers correlate with mine by chance? I just can't figure out how 2 new batteries are already dead after just sitting 24 hours. Makes me concerned because the car will be parked for 4 days while we are on a vacation this weekend. I don't see this getting fixed by Friday unless its easy to fix and relatively cheap. If you can tell me where we can locate this SAM control, if there is more than one god I hope not, and if its easy to get to. We will do the work ourselves. Thanks Pete!!
Expert:  Pete replied 1 year ago.

The 2002 model is an older model of the 163 chassis and your model is of the 164 chassis so they are different models unfortunately and the bulletins are different.

Unfortunately in order to find the source of the drain this will need tested which can require some time to do (usually anywhere from 2 to 8 hours to pinpoint it with the correct test equipment and correct wiring diagrams).Even if it does require a sam replacement the new sam will need to be set up and programmed by a dealer in order to work properly.

It is best to have this tested to locate the source of the drain then that component replaced.

Unfortunately this may take a day or more to have tested then the part has to be ordered in from there to repair this fault.

Thanks Pete

Customer: replied 1 year ago.
Ok, thanks much. I am reading in a Mercedes Forum of a n issue with SAM boards getting wet from water leaks. Some through real tail lights? Since we have just had torrential downpours for over 3 months here, I wouldn't doubt that if it is this SAM board, it has gotten wet somehow. Where you aware of these problems with ML 500 electronics getting wet and malfuntioning? Doesn't sound like a new issue...
Expert:  Pete replied 1 year ago.

The front sam is located under the passenger front seat and it can become wet from the ac drain being clogged or disconnected or from water or a spill in the back seat area.It is located under the passenger front seat,under the carpet which is under the duct work and then under a plastic panel.Once all this is removed there you will see the main large battery and the sam is to the right of it.

The rear sam is located in the passenger rear of the vehicle behind a panel below and to the right of the rear fuse box.

If there is any water in the sam unit the sam affected will need replaced.

Thanks Pete