Break service warning reset.

[Shadow_40]

I can't find anything on this so I apologise if I am duplicating an old thread...

I fitted new front disks/rotors and pads onto my 2002 Boxster S this morning, easy enough. I've driven the car and after a few miles the disks and pads seem to be bedding in nicely and the car is driving well. Unfortunately I now have a warning that comes on every time I start up (I'm at work now but from memory it's something like) "Breaks service now" it clears by pulling the computer stork towards me but a break warning light remains on and the warning is displayed after every start up.

Is there something I can do to clear this without paying a dealer to plug their diagnostic gear in?

[The Radium King]

did you replace the brake pad sensors or reuse the old ones?

[Shadow_40]

I fitted new sensors

[BoxsterSteve]

As Radium King suggests, if you have re-used your old wear sensors, it's most likely that's where your problem lies.
Replace them, or do as I did. Mine are stripped and spliced together, sealed with shrink tubing and zip tied to the back side of the strut. Presto, no more pad warning light. I'm OK with that because I visually inspect the brakes twice per driving season, so the pad warning sensors are just unnecessary fluff to me.

[Shadow_40]

I changed the disks because they were severely corodedon the back but the pads had loads of material left on them. I assumed the computer detected that I had done something and therefore threw up a code that must be cleared. Are you saying that's not how it works and that the computer is detecting an existing problem with the new wear sensors?

[BYprodriver]

When the pads are worn enough on the side where the sensor wire is inserted, to contact the rotor, it breaks the electric circuit. This lights the brake warning light. If the pad is still too thin to protect the sensor wire it will light up the warning light again.

[Shadow_40]

Ok let me clarify... My old pads are thick, loads of material left on there and the sensor wire never got anywhere near the disks. I have fitted new sensors into my new pads these have also never come into contact with the disks.

[thstone]

The system is very simple - if the circuit is broken (like when the sensor is worn by the rotor), then the brake service light is illuminated. And it will stay illuminated until circuit continuity is restored. No computers, no calculations, just a simple circuit.

And the sensor isn't really a sensor - it is simply molded plastic with a loop of wire in it so when the rotor wears it down, the wire connection is broken. Then the circuit opens and the brake service light comes on. Its about as smart as a rock. Or a twig.

Since you installed new sensors, my guess is that one of the sensors isn't making a solid connection where the sensor wire connects to the vehicle harness. Disconnect and reconnect each brake sensor from the vehicle harness (making sure that you have a nice firm connection and it is fully seated) to see if this solves the problem.

Otherwise, then you may have received a bad sensor that has an open circuit. You can test each sensor (checking for continuity) using a multimeter to see if this is the cause.