desperate help needed, funny noise when car switched off!!

[timbo1811]

Hi all, I have a c230K sport 1990, over the two years I have had the car I have had a persistent electrical fault, windows not working, central locking not working, alarm going off for no reason, unexplained flat battery,all is restored when I briefly disconnect the battery. Well today it started making a strange quiet high pitched beeping noise on the passenger side of the engine when the engine is off and the key is removed, (I think it might actually be going when the engine is running although it's difficult to tell), which only stops when I disconnect the battery. I would be extremely grateful if some one could tell me what this is.

Yours hopefully, Tim

 

[television]

Hi all, I have a c230K sport 1990, over the two years I have had the car I have had a persistent electrical fault, windows not working, central locking not working, alarm going off for no reason, unexplained flat battery,all is restored when I briefly disconnect the battery. Well today it started making a strange quiet high pitched beeping noise on the passenger side of the engine when the engine is off and the key is removed, (I think it might actually be going when the engine is running although it's difficult to tell), which only stops when I disconnect the battery. I would be extremely grateful if some one could tell me what this is.

Yours hopefully, Tim

The noise is could be the ABS pump system releasing presure, or the fuel sytem going down,that's normal, put up the first 6 numbers of the VIN and I will check for any mods a faults recorded for locking etc.

malcolm

 

[timbo1811]

Hi Malcolm, thanks for the speedy reply. wdb2020242, is this what you need? this noise has an electronic note to it, and was goin some two hours after switching off. after leaving the battery disconnected for about an hour when reconnected noise he gone!!

cheers Tim

 

[television]

The main one that I have is malfunction of windows, locking, wiper and turn signal. that is due to moisture in the rear door drivers side Can Bus system.

malcolm

 

[timbo1811]

Sorry Malcolm, but you'll have to explain 'can bus system'

Tim

 

[Flying Scot]

he he it is ethernet for cars

now do i have to explain ethernet?

i had a funny noise for days turned out to be the neighbours cat with it's tail under the front offside tyre

i made a video of it but it went all funny and looks like an exocet hitting a stange shaped building

only joking honestly

 

[television]

Sorry Malcolm, but you'll have to explain 'can bus system'

Tim

Can Bus is a multi checking system, for go, or no go, to all parts parts of the car. It can handle 3 two way signals at once, a signal is sent around the car and each part returns the signal as go or no go. the main signal at high speed checks important drive systems on the car, a slower one checks things like, seats, mirror's and the like, if water or moisture contaminate the system it will do funny odd things like windows opening or closing,I could make this a 5 page article, but no point as not many understand it. As flying scott says it is taken from the ethernet system, and adapted for cars.

Malcolm

 

[timbo1811]

Ok but is this making the noise? sounds like its coming out of the alarm. If its abs why would this stop when battery disconnected, infact why do gremlins seem to leave for a while when battery disconnected, they could be gone for weeks or days, the noise is new though.

Tim

 

[television]

Any noises when you turn off are always there, you have two very high presure system that slowly discharge. My car does it fo 5 mins after turning off.
Re disconnecting battery, this will normally clear faults that have built up, like for instance the CAN BUS,when the fault re accure's, the cycle is repeated until the offending item has been fixed.

malcolm

 

[timbo1811]

The noise is definately linked to the electrical system, it ceases when battery disconnected.

cheers Tim

 

[jberks]

On the noise - I'm not convinced its anything to worry about. All Mercs chatter on a while when switched off. The ECU etc are all on the front passenger side and (someone please confirm) there may be cooling fans that continue for a while after switch off. The fan may have become nosier but thats fine.
The acid test, if you leave it for over 1 hour is it still beeping or has it shut up by then?

 

[Fandango]

sounds like a fault with a cheap aftermarket alarm system. Disconnect, dismantle, discard!

regards
Karl