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New to this site so not sure if this is where I am supposed to post. But, here goes. I have a 2003 Mercedes s500 amg. It has 63,000 miles and hadn't been touched since 2016. Sat in a garage since then. So I expected some issues. First time driving it the serpentine belt snapped and idling pulley went with it. So I ended up replacing those on the side of 95. No biggie like I said I expected some problems. I've noticed when accelerating hard sometimes I get a strong sulfer smell. Also, randomly when accelerating the headlights flicker then all electrical goes. Radio, dash lights, gouges, everything. The car doesn't cut off and drives fine. Then, I pull over, turn the car off and back on and everything works again. But, something scary happened today. When going to accelerate to switch lanes it just stopped accelerating. Car still on, no dash light warnings, but gas pedal seemed to not work. Switched into manual and shifted myself and it worked fine. So I didn't take it out of manual after that just in case. Then, a mile from home the dash turned red saying maintenence required immediately with the battery light flashing. It seemed to be running fine so got it home and turned the car off. Restarted and after 30 seconds the warning went away. Could this be some sort of relay sensor? What else could it be? I plan on fixing myself as long as it's not too complicated so just need help diagnosing. TIA!!
Could be many things but the first things I would check are for corroded connections. First check under the passenger floor carpet there’s A metal panel. Unbolt it and you’ll find electrical junction box that often gets corroded. Here’s a picture.
In one person situation this entire junction box was corroded and they had to replace the entire thing with a used one from eBay.
Also check the battery cable connections in the trunk make sure they are tight and make sure the area below the battery is dry.
It can also be a bad alternator or loose alternator belt or poor wiring to or from the alternator. From sitting all those years it’s possible animals may have chewed on the wiring inside the engine compartment.
