04 E55 AMG: weird lighting behavior
Posted: Mon Jun 29, 2020 12:32 pm
I have been noticing this on and off mostly since I've owned it. And I believe it may be a moisture problem in the front left SAM (smart fuse/relay box).
It surfaced again after I washed it this weekend.
The symptom trend goes like this:
- Car gets wet. Headlights in auto. I had been messing with some other settings like "surround lighting" which turns on the fogs and parking lights when you open the door and it's dark. Kind of cool, a little like later model Fords except the fogs add a lot more light. I also turned on the headlight delay to 15s after ignition off as I prefer this setting on my auto headlight cars. But this is when I started noticing the issue. It started when I noticed my battery was nearly drained a while back. This must be what drained it. The little red light next to the P on the shifter stays on and it acts like the ignition is not fully off, so if the lights are in auto, the lights stay on. If I turn them off manually, it still doesn't shut everything down. Eventually I messed with more settings and that seemed to fix it. But this was temporary.
- This weekend when I washed it (pressure rinsed), some of the symptoms became....elevated. At one point, the little red light next to the P on the shifter was just going on and off. A bunch of different stuff was waking up and shutting down (like the steering column lock). Not too good.
I pulled two codes from the front SAM with my Mercedes scan tool.
I also did some sleuthing in my FSM (which doesn't make this easy). Apparently if I had the factory STAR system it would make this process much easier because it would give me suggestions about the code (that's right, I can't find info on these codes in the WIS system), and also allow a pretty thorough functionality diagnosis of any offending module (including the SAM in question).
But it seems like the EIS module (ignition module) is either errantly sending power to the front SAM to wake up (as in key on), or the front SAM essentially made this up. I will say during the issue I scanned the EIS and it NEVER commanded power to circuit 15R. Yet when I scanned the SAM it showed power and then no power on 15R. So I would think the issue is there. No codes in the EIS either.
Of course, this circuit is also shared with the wiper motor. And that circuit had the shoddy scotch lock wire tap which I finally ripped out (after the issue subsided with the car in the garage). I don't THINK that was causing anything but who knows.
Did some research and water issues are....common. My cowl cover has a seal up against the windshield and it is partially dry rotting. Water could be dripping down behind that and onto....something. Wiper motor, maybe even into the front SAM even though it has a cover. Maybe the wiper motor is soaked and back-feeding current into the SAM but it's not clear if it's seeing 12V errantly, or an actual wrong CAN signal. I don't think the wiper motor has a module on it.
So I ordered a new cowl cover (again this is common).
But Mercedes makes lots of improvements to their cars over time. So 05s and 06s got some additional anti-water stuff. One is this cover that actually goes on top of the SAM cover adding further protection. Ordered a used one from eBay.
https://www.ebay.com/itm/333132035041
Got that tip from my thread here:
https://mbworld.org/forums/w211-amg/787 ... t-15r.html
I am hoping that this will cure my issue. Worst case I'll have to pull the SAM out and see if I can figure anything out.
When dry, everything works properly, including the aforementioned lighting settings. So I think if I can fix the water issue I'll be good. So that's two water leak issues so far. I guess that's the downside to this thing living in a garage for 6 years...if it was parked outside it would have been fixed by now.
It surfaced again after I washed it this weekend.
The symptom trend goes like this:
- Car gets wet. Headlights in auto. I had been messing with some other settings like "surround lighting" which turns on the fogs and parking lights when you open the door and it's dark. Kind of cool, a little like later model Fords except the fogs add a lot more light. I also turned on the headlight delay to 15s after ignition off as I prefer this setting on my auto headlight cars. But this is when I started noticing the issue. It started when I noticed my battery was nearly drained a while back. This must be what drained it. The little red light next to the P on the shifter stays on and it acts like the ignition is not fully off, so if the lights are in auto, the lights stay on. If I turn them off manually, it still doesn't shut everything down. Eventually I messed with more settings and that seemed to fix it. But this was temporary.
- This weekend when I washed it (pressure rinsed), some of the symptoms became....elevated. At one point, the little red light next to the P on the shifter was just going on and off. A bunch of different stuff was waking up and shutting down (like the steering column lock). Not too good.
I pulled two codes from the front SAM with my Mercedes scan tool.
I also did some sleuthing in my FSM (which doesn't make this easy). Apparently if I had the factory STAR system it would make this process much easier because it would give me suggestions about the code (that's right, I can't find info on these codes in the WIS system), and also allow a pretty thorough functionality diagnosis of any offending module (including the SAM in question).
But it seems like the EIS module (ignition module) is either errantly sending power to the front SAM to wake up (as in key on), or the front SAM essentially made this up. I will say during the issue I scanned the EIS and it NEVER commanded power to circuit 15R. Yet when I scanned the SAM it showed power and then no power on 15R. So I would think the issue is there. No codes in the EIS either.
Of course, this circuit is also shared with the wiper motor. And that circuit had the shoddy scotch lock wire tap which I finally ripped out (after the issue subsided with the car in the garage). I don't THINK that was causing anything but who knows.
Did some research and water issues are....common. My cowl cover has a seal up against the windshield and it is partially dry rotting. Water could be dripping down behind that and onto....something. Wiper motor, maybe even into the front SAM even though it has a cover. Maybe the wiper motor is soaked and back-feeding current into the SAM but it's not clear if it's seeing 12V errantly, or an actual wrong CAN signal. I don't think the wiper motor has a module on it.
So I ordered a new cowl cover (again this is common).
But Mercedes makes lots of improvements to their cars over time. So 05s and 06s got some additional anti-water stuff. One is this cover that actually goes on top of the SAM cover adding further protection. Ordered a used one from eBay.
https://www.ebay.com/itm/333132035041
Got that tip from my thread here:
https://mbworld.org/forums/w211-amg/787 ... t-15r.html
I am hoping that this will cure my issue. Worst case I'll have to pull the SAM out and see if I can figure anything out.
When dry, everything works properly, including the aforementioned lighting settings. So I think if I can fix the water issue I'll be good. So that's two water leak issues so far. I guess that's the downside to this thing living in a garage for 6 years...if it was parked outside it would have been fixed by now.