Disconnected battery and problems when reconnected
Thread Starter
Member
Joined: Apr 2022
Posts: 81
Likes: 6
From: Florida, New Jersey
1981 380SL, 2003 clk430, 2009 s550
Disconnected battery and problems when reconnected
Hi, I have a very nice 2003 CLK430. I've been having problems with my top computer and read that it might be good to reset the car/computer by disconnecting the car's battery for 30 minutes or so, so I figured I'd give that a try. I was assuming that a reset would give the car a known good starting point. I need to add that prior to disconnecting my battery, by removing the ground from the battery, the car had absolutely no issues other than a wonky top.
So... after about 30 minutes I reconnected the battery. Now when I start the car I see a BAS, Brake Assist System error and the fog lights are on all by themselves and never go out. Please note that the car never moved and never had these issues prior to the reset. I did try resetting it again, (what could happen?) and got the same results/issues. I then walked away calmly and went overseas for three weeks for work. Upon my return, I reconnected the battery and nothing has changed and the car is still in the same sorry state.
So, my CLK is sitting in my driveway with no battery connection, so the fog lights don't kill the battery. Does anyone have a suggestion please?
Thanks!
So... after about 30 minutes I reconnected the battery. Now when I start the car I see a BAS, Brake Assist System error and the fog lights are on all by themselves and never go out. Please note that the car never moved and never had these issues prior to the reset. I did try resetting it again, (what could happen?) and got the same results/issues. I then walked away calmly and went overseas for three weeks for work. Upon my return, I reconnected the battery and nothing has changed and the car is still in the same sorry state.
So, my CLK is sitting in my driveway with no battery connection, so the fog lights don't kill the battery. Does anyone have a suggestion please?
Thanks!
Member
Joined: Jun 2024
Posts: 118
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From: Midwest
CLK 430
I also have a 2003 CLK430 Cabriolet. After disconnecting the battery and reconnecting it takes about 15 minutes and a drive for the BAS light to reset and then it will turn off.
Also, I have the battery drain issue, I currently have disconnected the fuse for the SOS system and that has kept the battery from draining for over a year. I think the fuse is #4. I have heard that this can also be fixed by going to the Mercedes Dealer to have them turn off the SOS system which is using its internal cell phone to try to call-in constantly.
Also, I have the battery drain issue, I currently have disconnected the fuse for the SOS system and that has kept the battery from draining for over a year. I think the fuse is #4. I have heard that this can also be fixed by going to the Mercedes Dealer to have them turn off the SOS system which is using its internal cell phone to try to call-in constantly.
Thread Starter
Member
Joined: Apr 2022
Posts: 81
Likes: 6
From: Florida, New Jersey
1981 380SL, 2003 clk430, 2009 s550
Thank you Andy, actually i found from chatting with ChatGPT that if the engine is running and you turn the steering wheel all the way to the right and then all the way to the left and then re-center the wheel, turn off the engine and restart it, the steering angle sensor recalibrates itself. You driving it essentially did the same thing.
I'm still stuck on the fog light issue though.
From what I've "Googled" it sounds like my front SAM is "confused" by the power outage. I've tried disconnecting the battery several times with more and more lights staying on now. My two fog lamps and parking lights all around the car are on now as soon as I connect the battery. This does kinda sound like a software panic of sorts on the SAM's part. I don't know of anyway to reset the SAM without driving to a service shop with a STAR or similar tool to do a reset. Sadly, my Topdon 900Lite doesn't talk to this car... Does anyone have any ideas?
Thanks
I'm still stuck on the fog light issue though.
From what I've "Googled" it sounds like my front SAM is "confused" by the power outage. I've tried disconnecting the battery several times with more and more lights staying on now. My two fog lamps and parking lights all around the car are on now as soon as I connect the battery. This does kinda sound like a software panic of sorts on the SAM's part. I don't know of anyway to reset the SAM without driving to a service shop with a STAR or similar tool to do a reset. Sadly, my Topdon 900Lite doesn't talk to this car... Does anyone have any ideas?
Thanks
Last edited by fischpj; Sep 22, 2025 at 12:22 PM.
Thread Starter
Member
Joined: Apr 2022
Posts: 81
Likes: 6
From: Florida, New Jersey
1981 380SL, 2003 clk430, 2009 s550
Well, here's what I've found. I took the car to a MB Indy shop, extremely nice guy, MB Certified and lots of awards. I told him I needed my SAM reset. He looked at me and laughed. My car doesn't have a SAM... He then leaned into my car around the headlight switch and sniffed. He had me do the same, I thought he was kidding. I smelled hot plastic. Apparently, this is a common CLK issue, bad headlight switch. I had not had the battery connected long enough for the switch to heat up in previous attempts, but after driving to his shop the smell and heat became apparent around the switch. I just ordered a used switch with a 6 month warranty. Hopefully, this is what the doctor ordered.
