Brake Warning Light, No Speedo When Cruise Control Activated

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James1507

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• Dec 18, 2014

• #1

So I put some new wheels on my A4 Avant the other night and then drove to work along the motorway using cruise control. Shortly after activating the cruise control it decided to cut out, a large brake warning light appeared on the dash, warning alarm, abs light and my speedo stopped working.

Now it seems there is nothing wrong with my brakes, all were still working fine.

Can anyone explain this? Have i knocked something putting on the new wheels or could the new larger wheels affect a sensor of some kind?

It only seems to happen when using cruise control.

Any thoughts???

 

alpesh26

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• Dec 18, 2014

• #2

It could be a faulty brake switch (fairly common problem) but I don't see how that would stop the speedo working

 

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James1507

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• Dec 18, 2014

• #3

Turns out it's not the cruise control that trigurs it. It seems to be as soon as you get upto speed on the motorway. Any ideas anyone?

 

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James1507

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• Dec 27, 2014

• #4

So i've replaced the brake light switch after a recommendation. Now this initially seem solve the problem but after a short drive it throws up the warning much easier than before. My question is will i now need to get the old codes cleared to stop this?

 

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James1507

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• Jan 2, 2015

• #5

Well it seems to turn out that the my brake light error / speedo issue was down to 2 slightly different tyre sizes being fitted front and back. Anyone had this before? My question is it a case of new tyres or can the computer be tricked / re programmed to prevent the error?

 

Denis Lenihan

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• Jan 3, 2015

• #6

Your wheel speed senders are detecting that your wheels are rotating at different speeds. The abs module is seeing this as a fault. All the faults you are experiencing are down to communication with the abs module. Refit the original wheels and road test. New wheels are all well and good but you have to stay within the parameters that the module expects to see. Have you compared the rolling radius of your new wheels to the old? Hopefully you don't have a fault with the abs module or the hydraulic unit.

 

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James1507

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• Jan 3, 2015

• #7

Fitted matching tyres to the new wheel and finally no error lights or brake issues what so ever!

 

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