Intermittent lock/ unlock problems
11-09-2018, 01:59 PM
#1
Newbie
Thread Starter
Intermittent lock/ unlock problems
I've found my issue reported for various models on the internet but all posts are from long ago, and no clear resolution to any. So I thought I'd try here.
PROBLEM DESCRIPTION:
Randomly, when trying to unlock my 2012 M-class (Diesel), nothing happens. It may take between a few seconds and 2 minutes but eventually, after a lot of clicking and waiting, it will unlock.
Note that the FOB battery is fine, and I tried a new one just to be sure. Also, I switched to the spare FOB and experienced the same random pattern of failure.
And oddly, whenever this problem is occurring, the tailgate will open just fine if I hit that button on the remote! Weirdest thing. So I can always climb in the back, but a) usually by the time I'm halfway straddled over the back bench the car will suddenly respond and unlock. Plus, pulling the door handle from the inside to unlock the car triggers the alarm.
I cannot reproduce the problem on demand, it just occurs sometimes. Confusingly, sometimes weeks will pass with no problems. Other times, it occurs multiple times daily, at least half the time that I go to open the car. Sometimes it occurs first thing in the morning, sometimes after having been in and out of the car for several hours without problems.
Having I suspect an electrical or code issue.
Code because it seems to happen in various models, and from model years 2008-2012 as far as I could assess from internet posts. Unfortunately, car dealerships in the U.S. don't seem to update code as part of servicing, and I don't know enough to tell them exactly what I want (other than I want every software update available which to me seems like something Mercedes should provide for free anyway??).
Alternatively, regarding a possible electric issue, I'm thinking either one of the relays (those black boxes on the fuse panels?) or fuses (I've pulled them all and none shows a problem) may be shaky. Maybe based on temperature, although there isn't a clear pattern that supports this.
Does anyone have a similar experience? Advice?
(For the record, I have other issues pointing to electric or electronic problems (I think), but don't want to confuse the issues: the blinker will randomly stop working, this has happened on 4 days out of the past 6 months, each incidence was weeks apart. Description: No reaction inside or out when setting turn signal. Hazards still work. Problem persists as long as motor is left running, Turning motor off and back on resolves the issue immediately, which argues against there being a problem with the switch itself. The problem came back after a few minutes of driving, I did the off/on multiple times on a 3-hour drive. That was a particularly hot day. Another time it was cool and rainy. In each case, on the next day the problem was gone, and I am currently not experiencing the issue. Like I said, the weirdest things going on with this car!)
MY CAR:
2012 ML-350 BLUETEC
no special features, no Keyless-Go, no modifications
70,000 miles
PROBLEM DESCRIPTION:
Randomly, when trying to unlock my 2012 M-class (Diesel), nothing happens. It may take between a few seconds and 2 minutes but eventually, after a lot of clicking and waiting, it will unlock.
Note that the FOB battery is fine, and I tried a new one just to be sure. Also, I switched to the spare FOB and experienced the same random pattern of failure.
And oddly, whenever this problem is occurring, the tailgate will open just fine if I hit that button on the remote! Weirdest thing. So I can always climb in the back, but a) usually by the time I'm halfway straddled over the back bench the car will suddenly respond and unlock. Plus, pulling the door handle from the inside to unlock the car triggers the alarm.
I cannot reproduce the problem on demand, it just occurs sometimes. Confusingly, sometimes weeks will pass with no problems. Other times, it occurs multiple times daily, at least half the time that I go to open the car. Sometimes it occurs first thing in the morning, sometimes after having been in and out of the car for several hours without problems.
Having I suspect an electrical or code issue.
Code because it seems to happen in various models, and from model years 2008-2012 as far as I could assess from internet posts. Unfortunately, car dealerships in the U.S. don't seem to update code as part of servicing, and I don't know enough to tell them exactly what I want (other than I want every software update available which to me seems like something Mercedes should provide for free anyway??).
Alternatively, regarding a possible electric issue, I'm thinking either one of the relays (those black boxes on the fuse panels?) or fuses (I've pulled them all and none shows a problem) may be shaky. Maybe based on temperature, although there isn't a clear pattern that supports this.
Does anyone have a similar experience? Advice?
(For the record, I have other issues pointing to electric or electronic problems (I think), but don't want to confuse the issues: the blinker will randomly stop working, this has happened on 4 days out of the past 6 months, each incidence was weeks apart. Description: No reaction inside or out when setting turn signal. Hazards still work. Problem persists as long as motor is left running, Turning motor off and back on resolves the issue immediately, which argues against there being a problem with the switch itself. The problem came back after a few minutes of driving, I did the off/on multiple times on a 3-hour drive. That was a particularly hot day. Another time it was cool and rainy. In each case, on the next day the problem was gone, and I am currently not experiencing the issue. Like I said, the weirdest things going on with this car!)
MY CAR:
2012 ML-350 BLUETEC
no special features, no Keyless-Go, no modifications
70,000 miles
