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VAGCOM measure rolling road speed?

Discussion in 'A4/S4 forum(B5 Chassis)' started by SonicDeathmonkey, Jan 19, 2009.

  1. SonicDeathmonkey

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    Can VAGCOM measure rolling road speed?

    Now that I have had the ABS sensor replaced, I need to find out which wheel has the clogged up rotor. Correct me if I am wrong here, but the abs sensor detects the passing of a toothed cog. If the gap between the teeth becomes clogged up, the sensor does not register any roadspeed on that wheel and the abs engages?
     
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  3. aragorn

    aragorn "Stick a V8 in it!"
    Staff Member Moderator VCDS Map User

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    i think in the ABS module under measuring blocks, it should show you all the wheel speeds...

    If awheel was registering no speed, the ABS would disable itself, give you the "BEEEEP BEEEEP BEEEEP" and turn your DIS into a nice red (!), it would also log a fault code for it.

    We had no ABS trigger ring on the rear for a few weeks, and if you pulled away and then braked the abs would trigger, but if you drove over about 10-15mph the ABS would register the fault and do the three beep warning as above, and the brakes would then work normally, albeit without any ABS.
     
  4. SonicDeathmonkey

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    Interesting. I just replaced the rear abs sensor.

    If I am braking from above 10-15 mph, all is well. Braking under 10-15, the abs engages, with the slight judder felt through the pedal.

    When the sensor was broken, the ABS light was on, but the brakes worked fine.

    Some time ago, Phil Walker said it was most likely a clogged up trigger ring, if thats the name.
     
  5. dieselfitter251

    dieselfitter251 Blow ma own trumpet?

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    Hmmmm, was it just the one sensor that was replaced? The pulsating brake pedal usually means a dodgey sensor. No other fault codes? Before my ABS system commited suicide I had the pulsating pedal and then after cruising at around 70-80mph the orange light would come on, trip the system and I'd be without ABS. It'd also log a fault. Have you experienced this yet?
     
  6. SonicDeathmonkey

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    LapTop has been playing up lately, so not put VAGCOM on the car since the single sensor was swapped, but with the old sensor, the abs light would come on as soon as i cleared out the codes. This sensor was the only fault reported.

    Since then, the light is off, but the judder is there. I will have to put vagcom on and see whats what.
     
  7. SonicDeathmonkey

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    When I view the measuring blocks, it's not obvious what I should be looking for. Can anyone help?

    I've not used this function before. Should I just click 'GO' on each of the three fields?
     
  8. dieselfitter251

    dieselfitter251 Blow ma own trumpet?

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    Aye, use channel 1. At stationary they should all 1km/ph as you move off tey should all increase. Press go and the system starts monitoring.
     
  9. SonicDeathmonkey

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    Sweet. Anyone know what this "vag scope" is all about?
     
  10. dieselfitter251

    dieselfitter251 Blow ma own trumpet?

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    Just a graph that plots value X against Time. Different colour for different systems. Speed. Cruise control etc.... Don't drive and look at it at the same time. You'll crash!
     
  11. SonicDeathmonkey

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    Dont know why, but when I drive and monitor the wheel speed, vagcom seems to lose connectivity. Any ideas?
     
  12. dieselfitter251

    dieselfitter251 Blow ma own trumpet?

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    Hmmm. Nope. Sometimes my connectivity just disappears too. Have to switch my computer on & off to get going again!
     

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