all instruments fail and no brake lights when brake pressed

[beeper]

Hi all, This is my first post. Mercedes230e 1991. 199.000miles, petrol engine. not bad eh!
I have a problem which started yesterday. When i apply my footbrake i have no brake lights and all instruments fail and the seat belt, door open lights in the overhead centre consol flash. There is also a buzzing noise from under the rhs dash behind trim in the region of the light switch.After a short time, 10sec, my instruments read as they should till the next time i brake.
Can anybody suggest what might be the problem. I know i should expect some problems in a car this age but it has been going like a dream since i bought it 10 years ago.
Thanks
Beeper

 

[Myros]

welcome aboard

This might sound a bit ronsealy, but you probably have a short circuit somewhere originating with your brake switch. Or, maybe some wires rubbed against your brake pedal and have bared themeselves and short out. 1st things first, check all the fuses, then head down in the pedal box, get the trim panel off and start looking. A new brake switch costs about a tenner, and should be your first port of call if you can't find any obvious shorts down there.

 

[television]

As Myros really, the brake lamp swítches on MB's are live, switch shown below.

http://www.detali.ru/cat/oem_mb2.as...+++717.401&CT=F&cat=222&SID=29&SGR=015&SGN=01

A short in on of the brake bulb holders will do it.

Welcome. Malcolm

 

[jberks]

A short in on of the brake bulb holders will do it.

Welcome. Malcolm

As Malcolm says - I once had a short inside a brake bulb that caused the engine to run without the key. These circuits are complicated so get a short with power backfeeding where it shouldn't and all hell breaks loose.

The first (easiest) thing I'd try is to remove both brake light bulbs and retest.

 

[beeper]

Hi guys,
You certainly know your stuff Myros!
After a lot of testing the auto electrician i called out diagnosed an open circuit on one of the wires from the brake light switch. He rewired and took a power feed from under the fuse housing from a redundant fuse holder that still had power but was not protecting anything. Once that was done it's been right as rain. Whole job took about an hour. The best sixty quid i ever spent.
Thanks to all who replied so promptly. You may here from me again but i hope not. It means i'm in trouble again.
P.S,. The rac could not diagnose the problem when i called them. They thought it was the relay which i replaced but still had the problem. Of course mercedes would not take back the relay as i had connected it!!! That was £75 up my shirt!!!
Regards to all
Beeper

 

[BarryG]

Nice result!
I like it when people report back, then we know if something similar happens on our own cars.

 

[Myros]

Glad to have been of assistance

it gives me a warm useful feeling. and maked me feel better about all the help I get from this forum.