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My 2006 A6 Allroad suddenly started showing a brake pad warning a week ago. All pads and discs front and rear are like new, hardly any wear. After disconnecting brake warning cables from both sides at the front the warning is still showing, there are no fault codes on the braking system. Can anyone advise what the fault may be. I don't remember connecting brake pad wear cables at the rear, think they are front only. Thanks
By the way testing the voltage on the supply side I am getting 10.36 volts on both sides with the ignition on.
There are no rear sensors.
check the plugs for crud or broken wires.
The sensors should be open circuit until worn away then the circuit earths via the brake disc.
The system works as a closed circuit to keep the light off, disconnect the wires and it will come on, you have to bridge the terminals. The problem is normally with the left strut harness. The function is not linked to the diagnostics.Quote:
Originally Posted by dan2485
Follow the wires to the loom or rear of dash binnacle, on my A4 cabby it was green/brown , slice in bridge wire straight to body earth, the light will never come back and the vehicle check system still works correctly.
Whilst you should always monitor your brake ware safely, this can save you hours of trying to find damage to the sensor wire and is what people using after market pad upgrades do to be rid of premature warnings.
I wondered why it was a double cable, the old system used to just be one cable, when the pad was worn the metal contact would make a circuit with the brake disc and light the warning. As my car is LHD would the offending cable still be likely the same side? Of course I visibly checked all cables and everything looked fine, why does one spur go into the stub axle?
As I got a voltage on both sides on the supply side sockets that suggests no open circuit on supply therefore the fault should lie on the pad side. My meter probes were too big to get in the pad socket and check continuity therefore I will have to modify my probes and hopefully will find one side open circuit, we will see. Thanks for all the advice.
The system has always worked on the broken circuit principle, never on a disc contact principle as this would result in a high hysteresis circuit which would result in warning light flickering.
Thank you Crasher, point taken