This one regularly flummoxes me.
If your C6 A6 has child locks on the rear doors, it's got diagnostics-capable modules for each, reporting their condition to the CAN gateway.
The brakes however, are on a simple 'not-gated' circuit - if the circuit is broken (when the element running through the pads is worn through), the light comes on [and as above, if the circuit breaks anywhere else - a connector, wiring etc. - the light comes on; similarly if it shorts anywhere, it won't come on].
...However, as we all well know, [throughout the range for as long as I can remember] if you look at the plugs funny, the light comes on. Similarly, if you shout at it to go off and not come on again, there's every chance it'll do that too. It doesn't NEED to be as complicated a system as for childlocks (in the above example, or countless other systems), but I am somewhat surprised that for a system as important as braking, the technology hasn't been developed to make it a little more reliable/consistent in its behaviour.
Case in point: A few weeks ago I spent a good couple of hours swearing at a caliper on my Dad's Golf Plus, which had begun to seize due to over extension through worn pads. No sign of a pad wear warning light, despite the car being equipped.
It's a strange 'throw away' statement to make, but effectively I disregard the system entirely - and just check them myself periodically with a mark one eyeball.
Not much help I know, but perhaps in some way reassuring to know that at least the condition isn't unusual.
All the best,
Rob.
