I thought this was a simple (key) battery issue, but it doesn't appear to be so. I left my daughter in my parked coupe while i went to buy her a sandwich. I may have locked the car with the smartkey remote as i walked away (force of habit). knowing her, she likely put the radio on immediately. a couple of her friends happened by and she got out of the car, leaving the passenger door ajar as she talked with them. she got back in the car and closed the door as i approached, and i noticed my foglights were flashing. as i approached the drivers door and saw it was locked, i attempted to use the smartkey remote to unlock to no avail. i told her to use the unlock button on the dash and that didn't work either. finally, she just manually opened the drivers door from the inside. the smartkey remote hasn't worked since. the indicator light looked a little faint, so I swapped the batteries with my spare key (I didn't want to use the spare key 'cuz the release button's the wrong color and I'd confuse it with my other key....). when neither key worked from my living room window, i figured i might have to go start the car with the key(s) to reset them or something, which I did. either key starts the car, but neither will lock the doors. I tell the entire stupid story in case there's a clue in there. anyone? is there a key-resetting process (I vaguelly recall seeing something while i searched for battery changing steps; something like turn key on/off so many times, press lock button so many times in so many seconds.....?


I wouldn't worry about it but I'm about to go away for a while and I don't want to leave the car unlocked.

 

Let me pull out my old notes and see if I can come up with something. This sounds familiar to a degree.

 

Let me add that the red LED on the key(s) does light, but the car lights do not flash. Also, maybe unrelated, my radio reception seems to have fallen off dramatically at the same time

 

Does your windows / sunroof open feature work if you get close to the door sensor and hold the unlock button?

 

I never had much success with that feature on this car; for the most part, anything I do with either of my coupe key remotes does nothing, as if I'm using the wrong key (but they do start the car). I emailed the SA at the dealership I occasionally go to; natch he wants me to bring it in and leave it.

 

I was just looking through all of my stuff and putting the key in the ignition switch should be all that is necessary to re-sync the lock/unlock buttons. You may have a bigger issue.

If I think of anything else I will post back. Make sure to let us know what the outcome is.

 

the unlock/luck function works off the RF portion of the key, seperate from the IR portion for lowering windows. Both functions would go bad if the key battery was bad.

With the radio reception going bad also may indicate a bad RF receiver in the car. Maybe the unit in/on the hatch glass?

 

i think the car is confused.. try removing battery leave it for maybe 10 mins then plug it in again. mabye it will work.

 

sounds like a joke, but you might be onto something! I just went out to try jscavo's theory, and NOW IT'S WORKING!! I swear I've been trying this close, far, and tucked under my chin (that's my usual method; makes your whole head a transmitter I've been told). Anyway, my Service Advisor has sent their field tech to my house, and Murphy's Law, it looks like i've got no problem!!!

 

so how do u do it ?? look like I got the same problem but I dont know is it because of my key battery or it is something else and please share.

Andy

 

I just went out and tested as jscavo suggested:

I never use that open windows/roof feature, 'cuz you have to be right on top of the door to do it, but if jscavo is right (and I'm sure he is) I wanted to determine if the whole key is messed up or just the RF; sure enough, from right on top of the door, both functions work.

jscavo, the wire that goes to the rear hatch is cloth-wrapped and must control lots of other stuff; how do I look at the RF connection?

 

what is the RF and IR ?? how did u do it again ? Im confused lol

 

InfraRed vs RadioFrequency; IR is in the door handles and RF is in the back window. The MB Road Service guy just left; my car is blowing fuse #8 (I think it's #*), a 7.5 amp fuse. If he holds a 40 amp fuse in there momentarily, my radio and key remotes work, so I've got a short. Oddly enough, my pano roof was fine and now that won't work either...same fuse.

 

ahh IC and where is your fuse box locate at? is it under the hood by the driver side??

 

Fuse boxes are everywher dude, rear hatch, left side dash, under hood; stff or hire someone (like I do!)

 

BATTERIES

 

New batteries in the remote (on sale at the supermarket, $1.50 ea) and a new battery in the car ($40 form MB road svc, nice story) have not kept the fuse from blowing. I think the short is in the alarm: I've never heard a sound from it, panic button does nill, and my kid opening the door prolly sent it over the edge. I plan to deal when I get back from Jamaica....NO PROBLEM!

 

lol i saw this thread when you started it and i have been having a problem with my driver door lock not working. so tonight i got in my car and was playing with the lock unlock button in the car and i did it so many times the car stopped responding to the button. i then used the remote and it didn’t work and i got really scared and thought about your post. i then put the key in the ignition and took it out and it started working again thank god. so now i have to figure out why my driver door look isn’t working. have fun in Jamaica

 

I'm not gonna worry about it till I get back, but I am considering throwing one part at it before I bite the bullet and let the dealer use the SDS to locate the short. I'm thinking the "alarm module", which I guess is the siren etc. and is behind the right front wheel. I've never heard a siren sound out of this car in the four years i've had it, even when pressing the panic button or simulating break-in by opening a locked door. That never bothered me 'cuz I think that sirens are annoying and unnecessary (who even turns around any more?). My thought is that when my daughter opened the locked door, the siren module tried its hardest to work and ultimately blew the fuse. somehow during all our diagnosis yesterday my pano roof stopped working, but it had been working earlier so I think we blew a second fuse. Anyway, anyone know the name or part number for that alarm module?

 

https://mbworld.org/forums/c-class-w...hen-wants.html

hope this helps

 

Thanks for pointing out that thread samaritrey; I will likely replace that alarm module soon (I posted on that thread that I found it online for $150).

Well, now that I'm back from vacation (Jamaica mon; no problem), here's an update on my situation:

First, a recap: before I went away, the dealership had suggested I call Mercedes and tell them I had a dead battery, which would result in them sending a road service tech to my house (I was quite unaware that, as a Mercedes owner, I am entitled to free road service FOR LIFE for jump starts, battery replacement, tire changing, and up to 3 gallons of fuel; like AAA without a towing benefit). Anyway, the road svc tech would be coming from this dealer and the SA would be briefing him on my real problem (the dead battery ruse was just to make it free). As I posted earlier, before he arrived, my pano roof was working, my key WOULD perform the windows up/windows down function (when standing real close), but the key WOULD NOT lock/unlock from any real distance, nor was AM radio working properly. jscavo's post had me isolating something in the RF area. For whatever reason (laziness? stupidity) I didn't check any fuses myself before the road svc guy arrived, and he started by doing so, reporting that #8 kept blowing (again, #8 is a 7.5amp that appears on the fuse list as pertaining to anti-theft, convenience locking, and remote trunk). He checked the car battery, found it to be the 7+ year old original one, and, though it was only slightly under 12 volts, suggested I replace it. Since he offered me a brand new one for $40, I agreed. After installing the new battery, he did a couple of things that a lot of you smarter members might have anticipated: he turned the steering wheel lock to lock to lock to reset the ESP; he held the front window buttons in the up position for 3 seconds to reset the express up/down feature of the windows. Fuse #8 was still blowing, and he diagnosed that there was a short somewhere. My smartkey was still not locking/unlocking, my radio reception was nil, and now my smartkey was no longer able to do the windows up/windows down thing when standing close. In addition, the pano roof would not open or flip up, but the sunshade would operate. I locked it up with the mechanical key and went on vacation.

Now back and well rested, I started to think that maybe an additional fuse must be blown for the pano roof not to be working, so I retrieved the Fuse designation sheet from the cockpit fuse box and started hunting. There's no listing of "pano roof", just "Tilting/sliding roof (SE)" which designates #9, a 25amp, so I checked it, but it was fine. After looking back and forth from the sheet and the fuse box(es), I realized that #32 and #33 were both missing altogether. Since they're among the fuses listed for Convenience locking (along with 8, 9, 21, and 22) I quickly popped some fuses in, also replacing the blown #8, then I crossed my fingers and tried the smartkey: success! Locks, unlocks, opens/closes windows, and, I'm happy to rport, AM radio is back (Go Sox!) Don't know how exactly the fuses went missing, or why replacing them seems to have worked, but I ain't questioning it (for now). Only trouble is that the Pano roof will not open.

I find it odd that the sunshade goes back and forth but the roof doesn't, as there are not different fuses designated. I'm no genius (as has been well documented here) but I'm thinking that there must be a roof resynchronization procedure, not unlike that of the express windows and ESP. After 3 seconds didn't do anything I STFFed, and read 5-10 seconds HERE and gave it a try (even tho' that thread was about a roof that was least opening partially). I went with about 20 seconds in each direction, and it did require all four directions, but it worked! So the whole thing only required some fuses and some re-syncing (tho' the new batteries in the key and car couldn't have hurt). And to think this issue had me disabled for days! And MBWorld calls me a Super Member? Ha!

 

The reason this problem arose was likely no power to the aerial amplifier

 

Glyn, I wish you had posted sooner!!! I still believe that locking my kid in the car, plus her "breaking out", is what blew that fuse!

 

Sorry - I missed your post. The minute you reported locking & radio it had to be key to antenna related.

 

BTW - this problem is sometimes caused by a poor antenna earth or damaged antenna wires when tints are done.