s211 fault code C249D

[65mick]

Have got fault code C249D test wiring vehicle speed-status signal for voltage. Have searched online and cannot find out how to check this voltage or where to check this voltage, got the code from a friends star machine.
Any help with this would be very appreciated.

 

[mersum1es]

your friend star machine would have given answer...

 

[65mick]

Thanks, it said to plug in a diagnostic plug but my mechanic doesn't have the relevant plug, so I was wondering if there was a way to test with a meter, also it told what the fault was and not what causes this fault, so I was wondering what causes this fault.
Ant suggestions would be appreciated.
My mechanic does manly vans and commercials, so has not got car diagnostic plugs.

 

[mersum1es]

So it was not SDS? SDS Fault codes would have instructed what to measure, start machine has WIS, and WIS has full electric circuit diagrams. My SDS has not conencted to internet so it is longish procedure to dig circuits and put them online... I might do that as a C219 (I believe they are similar to W211) since it also can be useful for me. So I am not promising anything, I'll tag you if I get some info. BTW try W211 E-Class, forum member 'königstiger' probably will dig SDS documents for you faster than I can do it...

 

[AMGeed]

C249 fault code refers to the SBC pump I believe.
Get the car to a Mercedes indy with Star Diagnostics to pinpoint the fault.
Your mechanic maybe good, but the Mercedes SBC system need looking at by someone experienced.

 

[65mick]

Hi, thanks the star machine code is C249D test wiring Vehicle speed-Status for Voltage, also the display displays the message brake service visit workshop, this only appears after the brake pedal has been depressed for about 10-20 seconds, if you don't depress the brake the warning does not appear. The brake light switch has been replaced, also the SBC pump does not wake up when you unlock the car, but does work when the star machine runs diagnostics on it and the result is its OK. I need to find out where to test the voltage. My mechanic was due to come back tomorrow with an older laptop wis but my son has tested positive to the dreaded co-vid so all testing will have to wait so any help with what I can do in the meantime would be much appreciated. The frustration is knowing the fault but not knowing what to test or what causes it.

 

[65mick]

The display I mean is the dashboard display ( Brake Service Visit Workshop)

 

[mersum1es]

Grounding point of SBC unit is prone to corrode. Easy to check, few cables connected under one bolt on top of the front wheel in engine bay.

 

[65mick]

Hi, ok thanks I will take a look, check and take off and clean and check with a meter on the ground point on the other side of the engine bay.