[Waylander]

The earth lead in the arch is for the brake pad wear sensor and has nothing to do with the speedo or abs


The abs pulse sensor is a closed circuit, that also provides a signal to the frequency converter in the fuse box, this converter provides the signal for the speedo


If you follow the wiring diagrams for the ABS you will see what I'm muttering on about


We had a interesting fault on a car here where the speedo would only show half the actual speed, the culprit was a duff frequency converter

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[unknown4u]

Good conclusion. But you can only check an abs sensor by using an ossiloscoop. Because you have to see the signal it produces. If the signal is not correct you'll can have dirt or disruptions. Only by cleaning the area gives you not the answer what it exacrly was. Faulty connector dirt or no ground or what else. The sensor in the tiptronic is mounted directly on the crown wheel. The abs sensors in the back meausures the difference between left and right (when cornering) in combination with the maininput from the engine/tiptronic.

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[Waylander]

I have had a little fun with manual cars ABS and if you spin a wheel as fast as you can by hand you can measure the mv output from the sensor


If they are all the same then fine, if you have one that's very different to the rest that's your faulty one


ABS sensors are basically hall sensors, they output a tiny voltage when the magnetic field is disrupted


I'm sure all the tip cars have the same wheel sensors as manual cars

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[blue968]

Hi Guys,

 

I know anything is possible but this is what im thinking, I have a feeling the little motor that turn the Speedo is bad and her is why. By the way its a 6 spd

 

After installing spare cluster and worked for a mile perfectly, I pulled it back out and pulled it apart and had seen the plastic gear was split in 1/2 which is why is just stopped working.

 

Installed original cluster it also worked for a mile or so then stopped, pulled back out cked all gears and manually turned the with pick as if the motor was turning the gears and all worked perfectly to prove the gears are all OK

 

reinstalled original cluster yet again, worked again for a mile and then stopped, hit the reset it then worked again for another mile or so.

 

Is there a way to apply voltage to the little motor and verify if its good or bad?

Not sure if it means anything but when the original cluster decides to work the trip millage has a jolting affect, it does not turn nice and smooth.

 

Thanks

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