ABS Offside Front fault not resolved

[Slkgirl1]

Hi , does anyone have experience of an ABS inoperable warning that isn’t resolved by replacement of the ABS cable, please? My car is a C250 auto registered 2011, model W204. My garage has a generic plug in diagnostic reader ( ie not STAR ) which reads ‘ Implausible Failure’ when he installed a compatible part made by Bosch. The battery condition is read as being ok. After several hours of checking he has given up and has suggested I get in touch with a non franchised MB garage.
Any ideas please?
Thanks.

 

[E55BOF]

Your garage is right; get the codes read with a STAR.

 

[Tuercas viejas]

Well as I am sitting in my workshop at "Cape Canaveral," & I have to state this is NOT rocket science and you DON"T need to STAR gaze to find the problem.
Rather you use an oscilloscope and read the wave form coming off the sensor harness at the ABS module connecter either directly with multi pin socket removed, or by back probing the wiring on the back side.
You have then to simply decide if you want a numerical frequency or a wave form signal.

If you get "nowt" trace it back to the the sensor and the the hub tone ring , maybe even the harness itself for short downs as well as high resistances.
If its all good, then its most likely inside the ABS module itself , so accurate diagnosis is key here.

Most shops these days have oscilloscopes & they are used for many diagnostic functions in Independent shops, even using a scanner feature in live data functions .
We use several stand alone units including PicoScope which comes out of the UK & Autologic scan tools as well, let alone good old American Snappy .
Picoscope even has a wave form library within the tool to compare your car's ABS signal with the factory actual.

PicoScope automotive lab scopes and diagnostic equipment

Award winning PicoScope automotive diagnostics, test equipment and oscilloscopes from Pico Technology. All you need to find faults fast

www.picoauto.com

All to easy for us "grubby handed rocket scientists", so when asking a shop if they can handle this problem ,simply ask if they have an oscilloscope and know how to use it !
Tuercas viejas



.

 

[Slkgirl1]

Well as I am sitting in my workshop at "Cape Canaveral," & I have to state this is NOT rocket science and you DON"T need to STAR gaze to find the problem.
Rather you use an oscilloscope and read the wave form coming off the sensor harness at the ABS module connecter either directly with multi pin socket removed, or by back probing the wiring on the back side.
You have then to simply decide if you want a numerical frequency or a wave form signal.

If you get "nowt" trace it back to the the sensor and the the hub tone ring , maybe even the harness itself for short downs as well as high resistances.
If its all good, then its most likely inside the ABS module itself , so accurate diagnosis is key here.

Most shops these days have oscilloscopes & they are used for many diagnostic functions in Independent shops, even using a scanner feature in live data functions .
We use several stand alone units including PicoScope which comes out of the UK & Autologic scan tools as well, let alone good old American Snappy .
Picoscope even has a wave form library within the tool to compare your car's ABS signal with the factory actual.

PicoScope automotive lab scopes and diagnostic equipment

Award winning PicoScope automotive diagnostics, test equipment and oscilloscopes from Pico Technology. All you need to find faults fast

www.picoauto.com

All to easy for us "grubby handed rocket scientists", so when asking a shop if they can handle this problem ,simply ask if they have an oscilloscope and know how to use it !
Tuercas viejas



.

Hi Thanks so much for taking the time to consider my question and offer advice.

 

[Slkgirl1]

Hi, thanks so much for considering my question and offering advice. My mechanic thinks that it’s something a bit quirky as he’s only seen this twice in his years of experience..presumably the solution to the first didn’t apply to mine!
Ive booked in for a STAR diagnostics check this afternoon so I’m hoping I can get to the root of the problem.
I think it’s time for a change … after 4 previous MBs I’ve fallen out of love. This car has been a pain!
Thanks again.

 

[pmcgsmurf]

Sounds like a problem with the mchanic to be honest rather than the car.

As @Tuercas viejas points out these are so easy to test.

I always double check by spinning a wheel that the sensors are not mixed up too and it has me changing a Left when in fact it needs a Right.