From: Jim [jim@928intl.com] Sent: Thursday, April 27, 2000 2:25 PM To: 928 Subject: [928] Re: Front brake sensors on 1987 S4 Brake pad " sensors " the automatic brake pad minimum wear thickness warning system is a small cube of plastic with a wire embedded in it . when the pad wear down too far it breaks the wire . If the wire is not broken the " sensor " can be used . The warning brain is looking for a complete circuit many times a P O will cut the wires at the plastic , strip the insulation and twist them together . This defeats the system Jim Bailey 928 International jim@928intl.com 79 928 5spd 80 928 5spd 68 911 5spd From: John.Veninger@cnacm.com Sent: Monday, December 04, 2000 6:11 AM To: ROSS, STEPHEN MAJ Cc: 928@list.928oc.org Subject: Re: [928OC Public] pad light >How does the car tell when the pad is a problem and how do I trouble shoot >this or disable it if nothing else? 2mm is the wear limit that the factory manuals state (pg.46-03) for the pads. Seems a little thin. There is a wear sensor on each brake pad (two per wheel). It is basically a piece of wire that completes a circuit. The brake warning light becomes lit when any one of the sensors wear or the circuit opens due to a broken wire. You can check each sensor with an ohm meter to see if it has an internal broken wire. The system can be disable (not recommended unless you have you wheels off once a month and inspect the pads) by twisting the sensor wires together and taping them out of the way of the wheel and brake. John Veninger 1990 928GT 928OC From: Wally Plumley [wplumley@bellsouth.net] Sent: Monday, December 04, 2000 8:57 AM To: ROSS, STEPHEN MAJ; 928@list.928oc.org Subject: Re: [928OC Public] pad light At 03:23 AM 12/4/00, ROSS, STEPHEN MAJ wrote: >Yesterday my brake pad light came on for no apparent reason. The pads on >the car are all fine since I just checked them last week when I put on all >season tires and they are all at about 75% left. The PO just change them >last year and I have put less than 5000 miles on the car since that time. >How does the car tell when the pad is a problem and how do I trouble shoot >this or disable it if nothing else? Basically the idea as a home burglar alarm - a loop of wire around the car that lights the warning when the wire is broken. At each wheel, there is a small plastic block, with an imbedded wire, that is inserted into a slot in the brake pad. If you let the pads go too far, it wears the plastic block and the wire loop away, breaking the circuit. If you keep an eye on the pads and replace them in time, you can carefully pry out the sensors and reuse them - otherwise, you have to buy new sensors. The sensors do not come with the pads. If your system is giving you false warnings, the circuit is broken somewhere. First, make very sure that the warnings are false. If a piston seizes in a caliper, you can get uneven wear, so that the outer pad looks perfect but the inner pad is worn out. If the pads are not worn, then start checking the continuity of the circuit. The connectors at each wheel are the prime suspects. If you really want to disable the system, just short the loops out. I don't recommend it. Wally Plumley 928 Specialists www.928gt.com