I took a look at the ignition module threads and the service bulletin. It seems the poor solder connection symptoms are the physical key in the ignition isn't detected and the car will shift into park while driving. Since this is a key fob button/keyless go issue, I'm hoping my problem is different. I'm going to check the wiring diagrams for the keyless go module and see if I can figure out why it might not be communicating.

 

I recently had an issue, link to thread, where the instrument cluster just went dead shortly after starting the car... scanning for codes showed every module reporting a lack of communication with the instrument cluster. Power, ground and CAN continuity all checked out at the instrument cluster. Pulling fuse for instrument cluster (to reset) didn't help. Ultimately, disconnecting the main battery for 10 mins resolved the issue and it hasn't reoccured.

The front sam (N10/1) is a "hub" for various signals, including the multiple CANs... disconnecting the battery appears to "reset" it. This was advice given to me, based on MB tech who noted that this often resolves CAN issues.

This was the LAST thing I tried, after pulling the cluster, carpeting, etc... Maybe worth a shot, before going in deep going to wiring/function diagrams, electrical checks, trip to dealer. Its also important to ensure your main battery is in good health, as the electrical systems are more sensitive to voltage and voltage drops.

 

I think this is pretty good advice, as I've seen a couple other threads and even some Youtube videos where disconnecting the battery, or pulling and re-installing fuses for various control modules fixed key communication issues. I don't think the car will mind, as I've drained the battery in my W220 a couple times and it has never complained.

 

Just curious if you've tried disconnecting the battery?

 

I've disconnected the main battery, both the main and aux batteries, and examined all the relevant fuses one at a time. I've also checked the wiring connections at the keyless go module, the antenna, and the antenna amplifier. I've also checked the ground connections in the trunk to ensure they are all tight.

The dealer won't order a key for me to run the diagnosis (requires 2 keys), as the government hasn't processed my title application yet (it has been about 6 weeks and counting). The dealer also said they probably wouldn't be able to program the key anyway without the keyless go working. Oh, and it's $600 for a replacement key! They did test the button functions on my fob and they are all working.

I've ordered a used Keyless Go module from Ebay with the same part, hardware, and software numbers to see if that allows me to establish communication. If that still doesn't work, then I think I'm going to have to start measuring resistance and continuity on the appropriate CAN networks. If that does fix the problem, I'll take the old module apart and see if I can figure out what's broken (it worked intermittently before failing, so likely a solder connection).

I guess the one thing I'd like confirmation of is whether or not Xentry should be able to communicate with the Keyless Go module. The car doesn't scan that controller in the "quick test", so it doesn't show a fault. My guess is it just queries all responding controllers and doesn't really know which ones should be present based on the VIN if one doesn't respond. However, this is my first Keyless Go car, so I'm not sure how the controller should respond to a direct query.

This is definitely much more of an adventure than I really wanted to deal with. However, I'd rather be doing this troubleshooting myself vs the dealer doing the same thing for $150/hr and getting nowhere. The dealer tried to sell me a $150 quick scan to identify the problem. Ha! I know that charge code, and I know exactly what it reports. It's useless.

 

I haven't confirmed with Xentry, but with our Launch if the module isn't responding it will not show up in the quick test... at least that was my experience with the cluster. At one point, it indicated there was no cluster (module). I can scan our '11 E550 w/ keyless go with Xentry and see if the module is accessible. I'm sure it is, as it'll need coding almost certainly.

 

It would be awesome if you could check it out some time. It'll be a few days before the replacement module gets here. It seems hit or miss on whether it will require coding. A couple guys on Youtube said they replaced their modules without coding, and the module wasn't even from the same type of vehicle or part number (but same hardware and software numbers). Either way, I should be able to code it with Xentry, as it's not on the "theft" list and shouldn't require contact with the mothership.

I can only imagine what face I'd make if Xentry told me I didn't have an instrument cluster! I did cause my cluster to go berserk when I had a cheap OBD2 scanner plugged into the diagnostic port while driving. The car was not amused at all!

 

Well, here its is:



I'm not sure what version of Xentry you have (or whom from)... but in my experience with a few modules I checked on our cars to see if updates to software were available required logging into MB mothership. However, I'm not fluent on Xentry... I know there's also module start-up activations, which I was hoping to use once I replace my blind spot radar (if needed)... but that might also be online.

Seems like DAS was offline and only good up to W211. W212+ is Xentry mostly online for coding. There's Vediamo, if you want to go down that rabbit hole and risk. There are people who will login for a fee for you to update software.

 

Thanks for confirming this module shows up just like the other auxiliary modules. I'm OK paying the dealer for an hour labor to do the coding if necessary. This certainly seems to be a step in the right direction! Now it's down to either wiring or the module.

 

My dealer charges $500 total for a replacement KeylessGO key. I just asked the other day as I contemplated remote start (and decided against it).

I was actually under the impression that the keys were ordered and arrived at the dealer already working. This is the first I've heard of the key needing programmed to the car.

 

I've seen regular keys for $300-400 and keyless go for $500-600... we're lucky for being been in the business, we pay wholesale. A regular was $ 210 ($154 key/$54 programming) for our wagon which only came with one and list was $265. Luckily the E550 with keyless go came with 2. I was under the impression the key is delivered with the manual key cut based on provided VIN, they still need to program it to the vehicle. At least they always charged programming.

 

I had to get a key for my 2013 S550 as it came with only one. The key cost $650 with tax and I understand it came from MB in Germany programmed based on my VIN. It took a few days to get it and it was still in the original shipping bag when I went to get it. Dealer did nothing with it.

We tested the key for door locks at the dealer and as it worked we thought it was all fine but a couple of days later I tried to start the car with it and it did nothing when I pressed the start button. Doors and trunk open just fine with it.

Thought to go back to the dealer but then for some reason I decided to take the start button out and see if the key starts the car using it as a regular key and yes, the car started when I turned the key in the switch. After this I replaced the button and guess what, the keyless start from the button now worked.

My thinking is that the key requires one start by turning it in the start switch before the keyless start from the button works. Wonder if this procedure is what the dealer calls "programming" the key for the car? I think all keys need to be made in MB in Germany and they mail them in. That's why it takes a few days to get the new key.

Anyway, my new key needed to be "programmed" to the car by doing one start with it as a regular key in the switch.

 

That's how it worked for me as well, got the key from the dealer and it just worked, I didn't have the car there and they never saw it. But is was 2010 and the car was an 2007, things may have changed since then with upgraded theft protection.

 

Arrie,

What you described is what I've read as well. My car already has all of the key tracks open, so the key should require no programming at the dealer. I've read it is possible to reject the programming charge, as they're not actually performing it. I also read starting the car with the key fob in the ignition is what synchs the key to the Keyless Go module. It also gets the key replacement back into the range I've read previously ($450+tax). I will let everyone know what my experience is with the key replacement if I ever get the Keyless Go module up and running.

In the mean time I'm getting my W220 back on the road. I installed an aftermarket alternator in a pinch, and on my 3rd warranty swap I broke off the transmission cooler fitting in the oil line. So now the front of the car is removed while I wait for the new radiator (with integrated transmission cooler) to come in!

 

Attached bulletin may apply requiring KG CU software update.

 

Ok guys and gals, I got the key fob and keyless go systems working. I swapped the keyless go module with the one from ebay and no change. After reviewing the wiring diagrams and realizing they didn't seem to make perfect sense (fuse 74 was a red and white wire and not red and yellow wire, and I for the life of me can't figure out the pin numbers on the keyless go module (Xentry and the wiring diagrams listed ground and power as pin 9,10, while the pin markings on the keyless go module revealed the ground and power were pins 1,15).

So anyway, after deciding the fuse assignments and wiring diagrams didn't make sense (I'm using information for the W212.091, which is what Xentry assigns when it connects to the car), I decided to just start pulling all the fuses in the trunk. I eventually stumbled upon a blown fuse in position 92, which the documentation showed as being for the start-stop function on the transmission. Well, I replaced fuse 92, saw voltage at pin 1 on the keyless go module (the replacement one), and everything started working.

So, I don't know the cause of the blown fuse, but maybe the old module was going wonky and blew it. It seems odd, as the keyless go module looks like a super low power module, so it's likely some other thing that feeds off that circuit (TBD). Either way, I have a different module in the car, it didn't require coding, replaced the fuse, and all is well. Now I just need to reinstall all the trunk carpeting and should be in good shape until the fuse decides to blow again.

 

Awesome! Glad you figured it out. I see two wiring diagrams for Keyless Go (up to 2014 and as of 2014). The as of 2014 (attached) does indicate Fuse 92 as power to N69/5.

 

You got it! I didn't see the two wiring diagrams listed for W212.091 as identified in DAS. However, I loaded up documentation for another W212 model and the above diagram appeared, aligning with what you provided! I see this fuse now powers the rear switching module and the upper and lower sensors. I have no idea what these are, but I hope they aren't the cause of the fuse blowing. Either way, at least now the problem is isolated and the wife is happy!

 

Those are for Option 871 (dotted square around, w/ Code 871 in the top left corner)... sounds like maybe the wave foot under bumper to open trunk? You'll often see dotted boxes with bolded codes meaning whats inside applies only to that particular option. Some diagrams are a nightmare to decipher.

I entered a random '14 E550 VIN into WIS, which I used for the above diagram and below fuse assignment for Fuse 92:

 

Ah ha, so this car is optioned with code 871. If the fuse blows again, I will certainly check the wiring to the hands-free access switching module. Now I need to look in the manual and see how this option works!

 

See attachment.

 

So of course I applaud you for all the work you've done to get to the bottom of this issue, maybe in fact the sensor for the hands free trunk is wonky, but again we see a fuse was the real culprit, we keep coming back to the recurring theme that it's usually something simple or something that happens once then goes away! Wondering now if your original keyless go module was actually fine?

 

I was wondering the same, swapping back in the original would confirm that. Then I figured, if he has something that works, might not want to mess with it. Another thing that struck me is the location of the hands-free module in the bumper... immediately I'm thinking of the radar sensor for blindspot that corrode and rot out.

I would just confirm the hands-free works, maybe check current draw across circuit (Fuse 92) and leave well enough alone. Next time KeylessGo acts up and the fuse it blown, you can dig deeper again.

 

Yes, I agree, I also don't know where he's located, I would imagine the cars located in dry climates would suffer less from this than those in the rust belt. Also from your diagram above if he has trouble, he can check his rear 110v outlet to see if the fuse blew again!
Good to know!

 

This is a great investigative thread with a solve and solution that will definitely help others in the future with similar issues. Thank you!