Quote:
Originally Posted by redriver666
Last week, the brake wear indicator light came on on the dashboard  Since you can't tell which brake pads are involved on a Boxster 986 (and it can't be diagnosed via Durametric either), I removed all the wheels today and visually inspected the pads. Just as I expected (I don't drive many miles a year), none of the pads were worn down to the wear indicator; in fact, all the pads still have at least 3 to 4 mm of material left before reaching the indicator  To be safe, I also disconnected the plug at each brake pad to measure the resistance; a short circuit in one of the plugs could potentially trigger a false warning. Below are 3 photos of the "operation".
Questions:
1. The resistance value shown on the multimeter (for all 4 brakes) is identical to that of a new wear indicator (which I had already ordered). Does this mean there is nothing wrong with my wear indicators?
2. What, then, could be the cause?
3. Is it true that the dashboard light only comes on when there is a "closed circuit"? In other words, when the wear indicator makes contact with ground/the brake disc?
But now for question 4:
4. After reinstalling all the old pads and indicators... the dashboard warning has disappeared (for now)... :? Anyone have an explanation? |
I’ll do my best.
The wear sensors are actually loops of wire, and so are close to being a short circuit (the 0.3 ohm reading that you see may well be intentional, to limit current thru that circuit). When the pad wears to the sensor, the rotor will cut it, and the resistance will increase. I believe that all four corners are wired in series, so all that the system can tell you is that one of the eight pads has worn to that point. What level of increased resistance is required to trigger that warning? No idea.
As to why your dash light came on, I would hypothesize that one (or more) of the connectors where the sensor plugs into the wiring harness was either loose or slightly corroded - most likely the latter. By disconnecting and reconnecting all of them, you cleaned up the connection, and the false positive has cleared itself.
Regards,
TC