Keyless Go button stopped working
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Joined: Mar 2018
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2012 ML-350
Keyless Go button stopped working
The Start button on my 2012 ML350 has stopped working. It was in intermittent fault for a week or so and then has completely stopped. All other Keyless Go functions work and the normal key works fine, but it would be great to have the keyless functionality back. I have opened the carpet un der the back seat drivers side to check that the module doesn't have any obvious defects or loose cables, but am wondering how to proceed from here. Could it be the button itself? I was under the impression that it was a purely physical button without electronics. I'm thinking of ordering a used module from eBay, but have some concerns that it something else causing the issue. Does anyone have any experience with this that might help?
Last edited by yakcmneb; Feb 25, 2025 at 11:42 AM.
Junior Member
Joined: Nov 2017
Posts: 33
Likes: 9
2012 ML 350 (W166)
The Start button on my 2012 ML350 has stopped working. It was in intermittent fault for a week or so and then has completely stopped. All other Keyless Go functions work and the normal key works fine, but it would be great to have the keyless functionality back. I have opened the carpet un der the back seat drivers side to check that the module doesn't have any obvious defects or loose cables, but am wondering how to proceed from here. Could it be the button itself? I was under the impression that it was a purely physical button without electronics. I'm thinking of ordering a used module from eBay, but have some concerns that it something else causing the issue. Does anyone have any experience with this that might help?
I'm experiencing the same issue with mine, also 2012. It started by draining battery if I left button in ignition and then it finally failed. Past few months when it was very cold, when I put key in, it did not even detected that I turned key on... I've bought MB Xentry to check what is going on with it, what I see on it showing Ignition Switch Module (EIS) two way transmitter failure. I think EIS failing, and needs to be replaced or refurbished. I'm doing my research now if I buy one from eBay with key/push button set, how to program it.. I will post actual error that I see via software in the evening when I get home.
Junior Member
Joined: Nov 2017
Posts: 33
Likes: 9
2012 ML 350 (W166)
Hello,
I'm experiencing the same issue with mine, also 2012. It started by draining battery if I left button in ignition and then it finally failed. Past few months when it was very cold, when I put key in, it did not even detected that I turned key on... I've bought MB Xentry to check what is going on with it, what I see on it showing Ignition Switch Module (EIS) two way transmitter failure. I think EIS failing, and needs to be replaced or refurbished. I'm doing my research now if I buy one from eBay with key/push button set, how to program it.. I will post actual error that I see via software in the evening when I get home.
I'm experiencing the same issue with mine, also 2012. It started by draining battery if I left button in ignition and then it finally failed. Past few months when it was very cold, when I put key in, it did not even detected that I turned key on... I've bought MB Xentry to check what is going on with it, what I see on it showing Ignition Switch Module (EIS) two way transmitter failure. I think EIS failing, and needs to be replaced or refurbished. I'm doing my research now if I buy one from eBay with key/push button set, how to program it.. I will post actual error that I see via software in the evening when I get home.
Output from Xentry.... Looks like now I need to figure out if I buy used unit from eBay how to go with programming it... I think existing unit is probably not repairable.
Last edited by vrmb; Feb 26, 2025 at 09:09 PM. Reason: adding more text
Junior Member
Joined: Nov 2017
Posts: 33
Likes: 9
2012 ML 350 (W166)
After a frustrating saga with my car, I finally resolved my issues and wanted to share the fix for anyone dealing with similar symptoms. Here's a quick rundown of what I was experiencing and how I fixed it:
Symptoms:
Cloning Process & Challenges:
Symptoms:
- Start/Stop Button Failure: The button stopped working. Previously, leaving it engaged drained the battery in under 12 hours.
- Cold Start Issues: The car struggled to start below 30°F. (I’m in MA, and it’s been warm lately, so I haven’t confirmed this fix yet, but the car starts reliably now.)
- Random Shifting to Neutral/Park: The car would unexpectedly shift to neutral when stopped, in park while moving under ~5 mph. This was especially jarring when backing up in an empty lot—sudden stop, and I’m thinking, “What did I hit?!”
Cloning Process & Challenges:
- The cloner couldn’t retrieve the key passcode from my original EIS, so I had to buy a new key ($150 extra).
- Cloning itself cost $100, but it took three attempts to get all the coding transferred correct
- Tool used: Topdon Phoenix (you can find these on AliExpress, but proceed with caution if you’re DIY-ing).
- Tip: Look for a local cloning service on eBay to avoid multiple trips. I had to visit the cloner a few times to get it right.
- Double-check your EIS part number and FSB version before buying a donor unit.
- If you’re sourcing a cloning service, check eBay for providers within driving distance to save hassle.
- Be patient—cloning isn’t always a one-and-done process.
