MackDaddyB

Hello All!

Having an issue with my 2005 SL55. Car was normal, went to the store, turned off my car as usual. When I came back to the car, I noticed that my fans were still on despite the car being off for almost ten minutes. I went home and started smelling burnt electric smell. Got home, turned off my car, and heard this buzzing noise coming from the front right of the car, behind the headlight area. The noise wouldn’t go away so I unhooked the rear battery. Upon hooking it back up, the noise continued so I just unhooked it and left.

Here’s a short clip of the sound.

https://streamable.com/q3q7m2

Any ideas?

pmercury

iTrader: (2)

open the hood
reproduce the buzz
take a plastic or metal pipe, and locate the buzz by using it as a microphone by putting it on your ear
then post your find here

Amir_AMG

Sounds like it could be where the alarm siren is located? Wouldn’t explain the fans still running unless it is very hot where you are. The siren is known for failing and very common

MackDaddyB

I’ll be trying to find the source today. Just was hoping that sound may be familiar to someone as I’ve never experienced that before. Thank you

MackDaddyB

Couldn’t duplicate it. It has vanished overnight with the battery off 😅. Will report if it comes back

BenzNinja

iTrader: (4)

then it could really be the alarm as Amir said
the battery inside died overnight, that's why you don't have any noise anymore
you can just unplug the alarm next time it happens
you can live without, nothing will trigger

you can repair those most of the time, split them open, then buy a new battery pack from ebay

kbob999

Correct me if I'm wrong, but in my 2003 SL55, the alarm is in the Left front wheel well, toward the back. Is the 2005 different?

The only obvious buzzing items in the right front are:

• the SBC pump, which would almost certainly throw a red brake warning if it had an issue
• the intercooler pump, which is just a coolant pump motor which shuts off when the key is off
• a stuck relay in the right front SAM...possibly connected to the radiator fan

I'm going with door #3 Mack.

BenzNinja

iTrader: (4)

totally correct, for some reason I read left
ooops

MackDaddyB

I, too, was going to go with door #3 if the problem persisted when I reconnected the battery, only because I noticed the issue with the fans still being on when I turned my car off. If it happens again, I know what I’ll be checking first.

I thought about it being a faulty alarm, but because it has its own battery and the noise went away when I unplugged the battery, I moved it down the list. Also, the noise was kind of weird.

Thank you, everyone!

latemodel21

add to that list of suspects ...
secondary air pump
heater circulation pump
windshield washer fluid pump

before listening to the audio (or gleaning from subsequent posts that there was NO red screen for SBC) I would have guessed that the burning smell was the ground connection to the SBC (there was a service bulletin/recall IIRC to improve this connection on early R230s) and that the noise was it's pump .... but now ???

an odd one for sure

Safe, Happy Holidays to all !
Chris