Break Wear Warning Query

JamesW1994

Registered User
Hi Folks,

I have a set lovely Brembo UV coated discs and sport pads on the way for my S3 8P facelift 2010 model. Now I am pretty sure the cars current pads have wear sensors on them, these new Brembo pads (from the images on the website) don’t look like they come with them. They are correct for the car as I have checked the PR codes etc and visually they look the same. Being a responsible owner I regularly check my tyres and discs / pads so I don’t rely on sensors for pads.

My concern is if these new pads don’t have wear sensors then the car will flag a code / disc pad wear warning. I have already checked VCDS and my instrument cluster does not list disc warning, I am 100% sure the warning will flag on the digital cluster screen (where MPG usually lives etc...)

How can I bypass this as its pretty much invetiable the code will flag. Does anyone know how the sensor works, will I be able to cut the exisiting pad cable and bridge it somehow to trick the computer?

I know it doesn’t sound good but I could do with a solution. Any input highly appreciated :)
 

Abi

Registered User
Yes this will definitely flag a warning on the dash and on vcds, obviously the flag on the dash is an MOT failure!
You can bridge the wires as you suggested to fool the sensor, but on your head if the pads get too low!!!
If I was you, I’d (like you said) bridge the wires from the connector to the old pads using the old wires and if possible pull the loom back into the engine compartment fully if possible. If I was an MOT inspector and saw this type of thing near the brake’s I would wonder what else has been tampered with. Out of sight is better!!



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JamesW1994

Registered User
Thanks for the response Abi, luckly where I live (Isle of Man) there is no such thing as an MOT :) if your car has 4 wheels it is allowed to be on the road lol. Granted the police check clearly dodgy vehicles but things like wear sensors do not flag up as problems.

Cool I will give bridging ago, I wasn’t sure how complex the sensor was but I guess its just a metal contact that creates as short of some sort. I will pull it into the bay to prevent it getting rusty in the future.

I would never let them get dangerously low anyways so wont be an issue
 
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aqibi2000

Registered User
Cut the wire off the old pad with the connector attached, bridge it the part of the wires where cut and plug in the connector like normal
 

Abi

Registered User
Thanks for the response Abi, luckly where I live (Isle of Man) there is no such thing as an MOT :) if your car has 4 wheels it is allowed to be on the road lol. Granted the police check clearly dodgy vehicles but things like wear sensors do not flag up as problems.

Cool I will give bridging ago, I wasn’t sure how complex the sensor was but I guess its just a metal contact that creates as short of some sort. I will pull it into the bay to prevent it getting rusty in the future.

I would never let them get dangerously low anyways so wont be an issue

I’m moving to the Isle of Man pmsl.

sounds like you have vcds but if not, do not turn on the ignition till both sides have been bridged, this will prevent an error code being placed in the ecu memory.


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JamesW1994

Registered User
I’m moving to the Isle of Man pmsl.

sounds like you have vcds but if not, do not turn on the ignition till both sides have been bridged, this will prevent an error code being placed in the ecu memory.


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Brilliant thanks for the tip :) what a coincidence lol. I am sure you will like it here, the Manx are a friendly bunch. If you are bringing your car over here it will go through something called ‘The Manx’ it’s like an MOT, but once it’s done and has it’s Manx number plates you are laughing that’s it. No more MOT’s lol. So feel free to do what you want to it, Decat it whatever lol... insurance would need to know mind but the goverment don’t care :)
 
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ScottyP45

Well-Known Member
The pad wear sensor works by detecting the end of the wire embedded in the pad, touching the disc when the pad is worn down, putting the brake (not BREAK) lamp or indication input on, so the warning can be shown on the dash. The same lamp that lights when the handbrake is applied, is used.

Don't bridge anything!

Just leave the wire disconnected and insulated unless you want the warning on the dash constantly .

If the new pads don't have the sensor, which is only a metal contact hidden in the pad material, then you can no longer use it.

Plus a wear indication is nothing to do with an MOT ....the tester uses his EYES and a metal ruler or calliper gauge to measure pad thickness against the factory spec.....not the light on your dashboard.
 
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aqibi2000

Registered User
The pad wear sensor works by detecting the end of the wire embedded in the pad, touching the disc when the pad is worn down, putting the brake (not BREAK) lamp or indication input on, so the warning can be shown on the dash. The same lamp that lights when the handbrake is applied, is used.

Don't bridge anything!

Just leave the wire disconnected and insulated unless you want the warning on the dash constantly .

If the new pads don't have the sensor, which is only a metal contact hidden in the pad material, then you can no longer use it.

Plus a wear indication is nothing to do with an MOT ....the tester uses his EYES and a metal ruler or calliper gauge to measure pad thickness against the factory spec.....not the light on your dashboard.

If you leave it disconnected it will remain open circuit.
It then depends on how the car is configured, if the loop wire is configured to short it to ground or if it’s pulled up via an internal resistor in the ABS module. The spec varies by OEM.
 

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Abi

Registered User
The pad wear sensor works by detecting the end of the wire embedded in the pad, touching the disc when the pad is worn down, putting the brake (not BREAK) lamp or indication input on, so the warning can be shown on the dash. The same lamp that lights when the handbrake is applied, is used.

Don't bridge anything!

Just leave the wire disconnected and insulated unless you want the warning on the dash constantly .

If the new pads don't have the sensor, which is only a metal contact hidden in the pad material, then you can no longer use it.

Plus a wear indication is nothing to do with an MOT ....the tester uses his EYES and a metal ruler or calliper gauge to measure pad thickness against the factory spec.....not the light on your dashboard.

654794f029a9c357af97161137dd6cf9.jpg


ANY warning light on the dash is an MOT fail!!!!
and you have to bridge the wires





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ScottyP45

Well-Known Member
Of course it will stay open circuit if not connected.

Why would anyone use a normally closed loop. Easy tested, touch it to earth - if the lamp comes on, leave it disconnected.

If it was an nc loop, how would it detect wear?? The simplest and cheapest option when designing a wear indicator is a ground return - caused when the pad is worn which then touches the disc. Why would anyone design in a more costly and complex solution?

The pads don't touch until you brake....so how are you going to detect wear unless you make a circuit when this happens. And an N/O one wire circuit would be pulled up already so the ECU can detect the switch from high to low when the pad wears down. High when good, low when worn

A simple lamp circuit would also just return the lamp neg side to ground.

Think about it!
 

ScottyP45

Well-Known Member
Ok I give up. I'm not saying having the light on is not a fail, I said the tester doesn't rely in a lamp, they check the pad thickness! I was showing you how NOT to have the light on when using pads with no sensors.

Joint the wires to what?? The pads have no sensor so what are you going to join the cars detector wires to?
 

Abi

Registered User
Of course it will stay open circuit if not connected.

Why would anyone use a normally closed loop. Easy tested, touch it to earth - if the lamp comes on, leave it disconnected.

If it was an nc loop, how would it detect wear?? The simplest and cheapest option when designing a wear indicator is a ground return - caused when the pad is worn which then touches the disc. Why would anyone design in a more costly and complex solution?

The pads don't touch until you brake....so how are you going to detect wear unless you make a circuit when this happens. And an N/O one wire circuit would be pulled up already so the ECU can detect the switch from high to low when the pad wears down. High when good, low when worn

A simple lamp circuit would also just return the lamp neg side to ground.

Think about it!

VAG group use a N/C loop, when the pad wears down it wears the copper link in the pad breaking the loop, this then triggers the warning on the dash, it’s nothing to do with going to ground.



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Abi

Registered User
Ok I give up. I'm not saying having the light on is not a fail, I said the tester doesn't rely in a lamp, they check the pad thickness! I was showing you how NOT to have the light on when using pads with no sensors.

Joint the wires to what?? The pads have no sensor so what are you going to join the cars detector wires to?

There are two wires from the connector to the pads which make the loop, it’s these two wires that need joining together to keep the loop.


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SootySport

Registered User
There are two wires from the connector to the pads which make the loop, it’s these two wires that need joining together to keep the loop.


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Correct, you need to simulate a loop in an unworn pad.
MOT tests are being revised this April so have a read up on the extra tests.
 
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ScottyP45

Well-Known Member
Ok ok I give up. Ffs. My face is shut.

I'm an electronics engineer of 30 years experience so I incorrectly assumed Audi had used a tried and tested method of designing a brake pad wear circuit. Not so, they went for a weird method but hey ho, can't win em all.

As they say in Dying Light.....Good Night, Good Luck.
 
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