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I could feel my brakes need some attention soon.Ihad a slight vibration in the front when I applied the brakes. Sure enough, my brake pad wear light came on( 83,000 miles). I ran VCDS to see if it would tell me which wheel the sensor was tripping, but after a full diagnostic check, nothing on brake pads faults, only think that came up on brakes was: 00541 - Brake Boost Vacuum System P1479 - 008 - Mechanical Failure. Why doesn't the brake pad fault show up? And if there is a Brake Boost issue, it doesn't tell me what wheel. Either way, I decided to replace my front rotors, brake pads, and sensors. It was time anyways. After completing the job, my brakes are much smoother, but the brake pad warning is still on and no other braking issues like a vacuum system problem. Of course this could mean the rear wheels, why can't VCDS tell me which wheel the fault (sensor) is tripping? and or...Are the Brake Boost fault linked to the brake pads?
 

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The brake pad warning circuit doesn't have a system to determine which corner is shorted because, once one is triggered, all of them need to be replaced.
 

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All of what needs to be replaced? Front and rear pads often wear differently. I usually either replace both front or rear brakes, depending on what triggered the brake warning.

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Are you just being argumentative?

You can replace front or rear or front and rear, but it would be false economy to simply replace one corner. I personally just do all four of them, but I also check the pads visually every time I rotate my tires. They have to be replaced sometime so I don't know what people think they're saving by staggering the front from the rear--it's not like the rears last through two front jobs or some extreme difference like that.

I guess jack it up on all four corners, take all the wheels off, and then...put them back on if they don't need changing but you're already halfway through the job at that point so it seems like a waste of labor unless you value your time at $0/hr. It's even worse if you take it to the dealer or a shop because it's going to wipe out your whole day--twice.

Strange place to be frugal, imo. Change out all four pads, rotors, and sensors, and don't think about it for another 4-5 years. I guess "need" is a strong word, but when it comes to brakes and tires I don't understand the savings in waiting to do some of the brakes in another 6 months.
 

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The brake pad warning circuit doesn't have a system to determine which corner is shorted because, once one is triggered, all of them need to be replaced.
If you don't DIY you take the car to a decent workshop and ask them to inspect and measure each rotor/disc thickness to see if they are still within service limits or not and also the pad wear on each corner.

With this knowledge you can determine which axle needs new pads and, probably given the very small wear limits, new rotors/discs

Mechanical good practice suggests doing all 4 corners at the same time but bank balance practice suggests one axle only if the wear levels are good on the other axle.

You have at least a couple of thousand miles when the wear light comes on to organise whatever replacements you decide upon.

A good independent shop can do one or both axles while you wait in an hour or two. Yes, the coffee may be crap and no, you won't get a free wash and vacuum but hopefully you won't be paying silly dealer prices!
 

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If someone thinks it's worth the time and hassle to do it piecemeal I'm not going to make an issue over that choice.

The point I was trying to convey was that even if the dash alerted the driver the front left brakes are worn all four corners would need to be inspected regardless of whether they needed to be "replaced" so it wouldn't change much to have discreet sensors on each wheel.
 

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Replacing all the brake pads at once, unless they were all worn down, just makes absolutely no sense. Only pads on the same axle need to be replaced at the same time. And there's no benefit to replacing all the pads at once, because there's no common work phase involved in replacing the front and rear pads (other than possibly lifting the car), and replacing them at once takes exactly the same amount of time as replacing them separately and adding those times up.

If you consider that at probably every second (or third) brake pad change you also have to replace the rotor, it makes even less sense to replace all the pads together, because you're not only wasting pad, but also rotor material with the premature replacement. And if it's the front pads that triggered the warning, then you're not only wasting the pad and rotor material on the rear brakes, but also the parking brake shoe material, which now also need to be replaced, just for the sake of doing everything at the same time.

As to the original question: you can determine which pads have triggered the warning only by looking at how much they are worn down, or if that's not conclusive or not possible because the caliper is covering them too much, then by either checking each sensor with a multimeter for continuity, or by taking a known-to-be-good brake pad sensor and connecting it to the wear sensor sockets at each wheel, and then looking whether the brake pad warning disappears. (Obviously the latter method won't work if there are more than one sensors that have been worn down. Or at least not with only one replacement sensor.)

The point is that as long as you can lift the car you can also access the wear sensor connectors without having to remove the wheels, and thus pinpoint the failed sensor relatively quick and easy.
 

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I never said anywhere to change brakes only on one wheel. I also find in my experience that the the front brakes on the Touareg/Q7 wear faster than the rears. I have gone over a year or more after changing the fronts before the rears needed changing. Why would I change perfectly good parts? The brake wear sensor on these vehicles already provides ample warning to replace the brakes.

I can also see the front and rear pad thickness on both sides of the rotor on both my Q7's with a flash light without removing the wheels. Not sure why I would want to waste money and do extra work for no reason.
Are you just being argumentative?

You can replace front or rear or front and rear, but it would be false economy to simply replace one corner. I personally just do all four of them, but I also check the pads visually every time I rotate my tires. They have to be replaced sometime so I don't know what people think they're saving by staggering the front from the rear--it's not like the rears last through two front jobs or some extreme difference like that.

I guess jack it up on all four corners, take all the wheels off, and then...put them back on if they don't need changing but you're already halfway through the job at that point so it seems like a waste of labor unless you value your time at $0/hr. It's even worse if you take it to the dealer or a shop because it's going to wipe out your whole day--twice.

Strange place to be frugal, imo. Change out all four pads, rotors, and sensors, and don't think about it for another 4-5 years. I guess "need" is a strong word, but when it comes to brakes and tires I don't understand the savings in waiting to do some of the brakes in another 6 months.
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IMO it seems like more than ever these threads on here are becoming argumentative over minor details, does anyone really think a DIY'er would change just the front left brake pads and not the right ?

If someone asks what seems like a "dumb" question just ask for clarification and offer the reasons why it should be done differently......

At least on the Audizine.com forum I follow for my A4 they have a thread "Ask a Dumb Question" so if you don't know something that others might consider so basic you can ask the question without fear of being beaten up over it.
 

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Replacing all the brake pads at once, unless they were all worn down, just makes absolutely no sense. Only pads on the same axle need to be replaced at the same time. And there's no benefit to replacing all the pads at once, because there's no common work phase involved in replacing the front and rear pads (other than possibly lifting the car), and replacing them at once takes exactly the same amount of time as replacing them separately and adding those times up.

If you consider that at probably every second (or third) brake pad change you also have to replace the rotor, it makes even less sense to replace all the pads together, because you're not only wasting pad, but also rotor material with the premature replacement. And if it's the front pads that triggered the warning, then you're not only wasting the pad and rotor material on the rear brakes, but also the parking brake shoe material, which now also need to be replaced, just for the sake of doing everything at the same time.

As to the original question: you can determine which pads have triggered the warning only by looking at how much they are worn down, or if that's not conclusive or not possible because the caliper is covering them too much, then by either checking each sensor with a multimeter for continuity, or by taking a known-to-be-good brake pad sensor and connecting it to the wear sensor sockets at each wheel, and then looking whether the brake pad warning disappears. (Obviously the latter method won't work if there are more than one sensors that have been worn down. Or at least not with only one replacement sensor.)

The point is that as long as you can lift the car you can also access the wear sensor connectors without having to remove the wheels, and thus pinpoint the failed sensor relatively quick and easy.
sir,
you make lots of assumptions without understanding the nature of your Touareg brakes... they share the same Brembo performance criteria as Ferrari... this isn’t like the Japanese, American, or front or rear wheel drive German cars, which all use Grey iron rotors and lack the technology built into the Touareg/Cayenne driveline.
These Brembo systems use High Carbon iron rotors, a differentially softer material than grey iron, that provides greater performance characteristics, but sacrifices durability. High carbon will always wear apace of the brake pads, so when the sensor trips, you’ve got a window to replace with safety in mind. But don’t imagine for a second that these parts aren’t wearing covalently! This is a matter of pure physics... not style of driving, etc. If the sensor trips, the rotors will be at or near minimums such that nothing can allow their reuse... they will progressively wear well below minimum if reused, thereby leading to premature brake failure if all components are not replaced. Physics, not driver or driving style ...

I’ve personally sold in excess of 3,000 sets of these brakes. If anyone needs accurate and correct, solid advice or info, I’m happy to discuss with anyone that calls me. I’m here to support the members’ parts needs. I sell complete brake packages with Pagid OE parts or Raybestos components to offer the best, most reliable solutions for anyone’s Touareg or other platform vehicle.
The Road to Perdition is paved with a lack of understanding of what’s needed to service these brakes competently... you must replace all related wearing parts to include caliper pad hardware, sensors, pads, and rotors. All T1/2 trucks should follow a four wheel protocol with every brake job, as the four wheels will wear equilaterally.. T3 trucks need just a bit more review, but most should produce a four wheel job.. deviation from this is due to the lack of a true off road capable four wheel drive transfer case on these models that may offer an option.

Reuse of brake rotors is strictly contraindicated.

Geoff
 

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Hi ya'll. Can anyone advise the thickness (or lack thereof) at which the rotors and also the pads require changeout on a T3 (build 2015).
I have started getting the 'check pads warning' but am aware of the dealer's desire to try to bankrupt me. TIA, Dub
 

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You probably have about 3 to 4mm left which will be good for a couple of thousand miles whilst you find a workshop which will do the job correctly and probably at a cheaper price than a dealer.

You will most likely new new discs as well as pads.
 
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