S211 Avantgarde - rear LED lights flip randomly from main to backup and to main
Thread Starter
Newbie
Joined: Oct 2021
Posts: 4
Likes: 0
From: Kraśnik, Poland
2004 S211 3.2cdi, 1992 W201 2.0
S211 Avantgarde - rear LED lights flip randomly from main to backup and to main
Hi guys. Sorry if that problem was discussed in a different thread but I couldn't find any.
I have a very persistent issue with rear LEDs in my car. It was originally equipped with LED lights so that's not any sort of conversion. The issue is that after starting the car and turning on the lights it shows 6 errors pointing to the left and right rear LED lights, informing backups were switched on. For the first I'd say 2 minutes a "disco" starts and lights switch from main to backup then to main, then right stop flashes and then again to backup. At some point the switching will stop remaining either on backup lights OR occasionally the LEDs will work after the disco effect and remain as such until I switch the car off. Cold or hot start does not seem to play any role. I noticed that the more times this problem comes up the bigger chance is lights will remain in backup mode after the 2 minutes, I think that's intended. Any help would be appreciated.
I have a very persistent issue with rear LEDs in my car. It was originally equipped with LED lights so that's not any sort of conversion. The issue is that after starting the car and turning on the lights it shows 6 errors pointing to the left and right rear LED lights, informing backups were switched on. For the first I'd say 2 minutes a "disco" starts and lights switch from main to backup then to main, then right stop flashes and then again to backup. At some point the switching will stop remaining either on backup lights OR occasionally the LEDs will work after the disco effect and remain as such until I switch the car off. Cold or hot start does not seem to play any role. I noticed that the more times this problem comes up the bigger chance is lights will remain in backup mode after the 2 minutes, I think that's intended. Any help would be appreciated.
Last edited by hex87; Sep 11, 2022 at 07:35 AM.
Thread Starter
Newbie
Joined: Oct 2021
Posts: 4
Likes: 0
From: Kraśnik, Poland
2004 S211 3.2cdi, 1992 W201 2.0
Took nearly a year of occasional attempts to fix it but it's working at last. If anybody ever gets that same thing it would be either the LM2904 operational amplifier found on the LED board or the board itself. In my case it was the board because soldering a new LM2904 chip did not help. The first two messages that appear on the dash indicate which lamp has the problem - in my case they pointed to the right one. You can also remove the lamps and connect them inside the boot on opposite sides (left one on the right, right one on the left) to make sure it's actually the indicated lamp that has an issue. Not sure it's a common problem or I was unlucky but since factory new boards are literally unobtainable in my part of the world I got a 2nd hand one with exactly that same issue, after running out of options I got another 2nd hand one and finally everything works. Hope this helps someone.
