Brake Pad Warning Light

I followed the terrific video from KS on changing out the brake pads on my '08 CS. Note: I allowed my local Porsche dealer, for a very high fee, to install Pagid pads for the track events I did over the summer and fall. I believe I did everything correctly to reinstall the original OEM pads, including connecting the brake wear sensors. However, the Brake Pad Warning lights are still showing up within the dash board dial. Any ideas on how to rectify?

Was the brake pad waring light on before you changed pads? If so you have to replace them with new ones.

I'm not sure about that. I got the light, which came on when braking hard and then went off and the light did not come back on when I installed the new pads and installed the sensors. I cleaned the sensor wire loops some. I had the impression that the loops carry sensor signal voltage that gets grounded when they come in contact with the rotor, but I realize that the system could also work by wearing through the loop and interrupting the circuit. It just didn't occur to me that a Porsche would design a wear sensor that gets destroyed to indicate a condition. I would appreciate enlightenment.

No. The warning lights only showed up when the OEM pads were removed and replaced with Pagid race compound brake pads. The OEM pads only have about 4K miles on them.

The brake pad sensors for the Cayman are similar to the ones on my wife's VW Touareg. The sensor that fits into the pad wears away till it exposes the wires and breaks the circuit causing the light on the dash to come on. The sensors should be replaced when the pads are changed.

Better still, visually inspect your pads and change them before you actually burn through a sensor. They are transferable as long as they haven't burned through yet. It just takes one to trigger your light, so that is the only one that needs to be replaced. I have mine tied back. It is cheaper to replace your pads a little early than to change all of the sensors every time, IMO. On a side note, I know someone with PCCBs who had the light come on. He drove home on the freeway and took it in to the dealership immediately. His rear rotors were already damaged and needed replacement for $10,000. The sensors are not a guarantee that you will not damage your rotors. Porsche picked up the tab for the replacements in this case.

In mycase, the OEM pads are not overly warn (yes, I did a visual inspection). The OEM pads only have 4K miles. They were fine before I replaced them with the Pagid pads for track use. Because the Pagids squeal, I decided to put back the OEM pads, since I do not plan to do another track event until March '09.

The light can also come on if you wet the sensors....they short then when they dry out they work again. Did you drive throught a puddle of water. Mine did the same thing last spring during a huge rain storm.

Remember the Pagids do not have a spot for the sensors to go back into. I have Pagid Blues and I went I went through the OEM pads and the light came on I put in new sensors but zipped tied them because there is not place for them to fit back on the Pagid pads. Could be they did not replace the sensors after you went through the OEM pads and replaced them with Pagids....so you still have the old sensors that can't close the circuit to turn off the light.

This is not a puddle problem. The Porsche dealer installed Pagid race compound pads at 4,000 miles for some upcoming track events. I was told the warning light would display on the dash controls since the Pagid pads do not have the sensor wiring of OEM pads. I figured once I re-installed the original OEM pads and connected the sensor wires (male/female socket mounted behind the brake calipers) the warning lights on the dash would go away. But it didn't. I'm trying to see if anyone else had this same experience and can help me trouble shoot.

When I put my track pads in, I zip tie the sensors back instead of unplugging them. Since the system apparently works on an open circuit methodology, then disconnecting the sensors would cause the light to illuminate as you describe. Since it didn't extinguish when you reinstalled the sensors, one possibility is that the condition is latched in the computer and must be reset by PIWIS, but that does not fit my experience with the light coming on then going off with no intervention. The only other suggestiong I have is to disconnect each sensor and do a continuity check to detect an open sensor or wire.

Thanks Kenny. I'll try the continuity test, as you suggest.

Kenny is correct - this is a basic open/closed circuit thing, and it doesn't need a PIWIS machine to turn it off... if the circuit is closed, the light will go out. If you are a person who will be checking their pads periodically, and doesn't really need the warning, you can tie them back as some have suggested. What my tech said to do, which I have done, is... I cut the sensor wires to about 1" long, then stripped the last bit of each, twisted them together, and put a couple of drops of solder on them. Then wrapped the end with a little black electrical tape. The circuit stays closed, and there's nothing to come loose or is wrapped around under there... brad

Thanks Beez. That's a good suggestion. I do plan to change the pads back and forth for track events, so I can visually stay on top of wear. If the Pagid pads didn't squeal so bad in day-to-day , I would simply keep them on. I love them on the track.