bc6t Posted June 29, 2005 Report Share Posted June 29, 2005 Just changed front pads and rotors. Prior to changing them (2 days ago) I was getting the "change brake pads" DIC message which would come on after I pressed the brakes firmly. Once acknowledged with Info Up the message would go away until the next time I started the car. Now with the new pads and rotors (aftermarket - not GM) I still get the Change Brake Pads Message. The sensors were carefully removed and re-attached on the new pads...I would expect them to be fine.... When I disconnect both sensors from the pads, I still get the message. I imagine I can short them at the connector - but this is not a fix. GM (Canada) wants $32 USD per sensor - I refuse to be financially raped for what appears to be a $5 part. BMW charges only $8. So, my question is how do they exactly work? Can I re & re them myself? Is it simply a wire that sets the fault once it touches the metal on the rotor or is it 2 separate contact points that need to complete a circuit once they touch the rotor? I can't really tell. I assume it's triggered by a 12 volt negative drop at the sensor harness? Any ideas would be appreciated... Tom. Tom R. 1998 Cadillac STS with 102K Miles Link to comment Share on other sites More sharing options...
JimD Posted June 29, 2005 Report Share Posted June 29, 2005 One (or more) of your pad wear sensors is either open or disconnected from the chassis wiring. The monitoring circuit expects to see a ground through all four sensors in series; this condition does not display the message. If one of the sensors is worn to an open condition, or the circuit is open because a connector is not connected, the message is displayed. Jim Drive your car. Use your cell phone. CHOOSE ONE ! Link to comment Share on other sites More sharing options...
OynxSTS Posted June 29, 2005 Report Share Posted June 29, 2005 Hey Tomba, If you need the $32 Buck sensors let me know I still get parts at my dealer at the freinds and family price...Which usually works out to ever so slightly less than gmparts.com after you factor in shipping... Good Luck One other thing to consider... What do the back pads look like? Greg Easin' down the highway in a new Cadillac, I had a fine fox in front, I had three more in the back ZZTOP, I'm Bad I'm Nationwide Greg Link to comment Share on other sites More sharing options...
Dadillac Posted June 29, 2005 Report Share Posted June 29, 2005 I have the same problem. The change brake pads warning came up today on my way to work. I stopped by Pep Boys this evening to buy new pads. I changed the fronts about 8 - 10,000 miles ago, so the rears must be shot. I bought Hawk performance pads, as they do not stock Raybestos QS (my favorite). The Hawk pads do not have the cutout for the wear sensors. I taped up the passenger side sensor, and put it out of the way. The driver side sensor is shot. All that I have is a wire, no contact. The contact didn't even fall out when I removed the old pads. It must have been gone for some time. Again, I taped it, and set it out of the way. The message still shows upon start-up, and I also have a ABS C1246 Current code. What can I do? I cleared the code, but it continues to show. Don "Modern warriors saddle iron horses of chrome." Link to comment Share on other sites More sharing options...
JimD Posted June 29, 2005 Report Share Posted June 29, 2005 Your C1246 is telling you that one of your pad wear sensors is open. No sure what "contact" you are describing. You can easily bypass any defective pad sensor at the chassis connector. Just connect the two connector pins together with anything conductive that will fit in there. Might be a good idea to waterproof the connector in case you decide to go with the correct pads and sensors in the future. Jim Drive your car. Use your cell phone. CHOOSE ONE ! Link to comment Share on other sites More sharing options...
Dadillac Posted June 30, 2005 Report Share Posted June 30, 2005 So if I jump the wires together, the code will go away? Don "Modern warriors saddle iron horses of chrome." Link to comment Share on other sites More sharing options...
JimD Posted June 30, 2005 Report Share Posted June 30, 2005 Yes.. IF the sensor you are bypassing is an open circuit. You could have more than one open sensor however. Jim Drive your car. Use your cell phone. CHOOSE ONE ! Link to comment Share on other sites More sharing options...
bc6t Posted June 30, 2005 Author Report Share Posted June 30, 2005 So how does the sensor actually work? If its triggered on by an open circuit then I assume that there are 2 wires/contacts on the brake side of the sensor that must be closed in order to not get the DIC message. Logically, though, I thought that it should normally be an open circuit and when the brakes wear down the 2 separate contacts/wires would touch the rotor and close the circuit, hence triggering an DIC message to change the pads. If this is not the case, how do the sensors actually work from a technical perspective.... If I new this I could proably retrofit the sensors myself and salvage them.... Thanks... Tom R. 1998 Cadillac STS with 102K Miles Link to comment Share on other sites More sharing options...
JimD Posted June 30, 2005 Report Share Posted June 30, 2005 I do not have access to the internal schematic of the EBCTM but this is most likely the logic that is used. A signal level voltage is fed through R101, through all 4 pad sensors in series, to ground. When the pad sensors are all in place and not damaged, the voltage measured at the "trigger" point is low. Very low. Opening the external circuit at any pad sensor (or any connector point) will remove the ground that R101 can see. The voltage at the "trigger" point rises to 5 volts and that rise is used to switch on another device that controls the DIC message. When a brake pad and sensor has been worn to the point where the wire is open, the "best" repair is to replace that sensor with new. Jumpering around an open sensor disables the early warning for that position. More than you wanted to know. And readers please note this info deals with '98 to '04 Sevilles specifically. Other models might be the same or similar. Jim Drive your car. Use your cell phone. CHOOSE ONE ! Link to comment Share on other sites More sharing options...
bc6t Posted June 30, 2005 Author Report Share Posted June 30, 2005 Thanks. This is what I needed to know so I can use my multi-meter to determine exactly where my faulty sensor is. I will probably not jimmy it like I originally thought, but will go to a wrecker and get a sensor that is still in good working order and replace the one that is toast. It appears from this expalnation that the sensor is supposed to go up in smoke (circuit openned) once triggered and thus a new one should always be installed with pads if a DIC message was recevied. I wish I knew this before buying after-market brakes since the OEM brakes were just a few bucks more and probably included the sensor.... Tom. Tom R. 1998 Cadillac STS with 102K Miles Link to comment Share on other sites More sharing options...
JimD Posted June 30, 2005 Report Share Posted June 30, 2005 Thanks.... It appears from this expalnation that the sensor is supposed to go up in smoke (circuit openned) once triggered and thus a new one should always be installed with pads if a DIC message was recevied. I wish I knew this before buying after-market brakes since the OEM brakes were just a few bucks more and probably included the sensor.... Tom. Glad to help. Most of the pad message problems I have seen here were reported after having brake work done. Caused by leaving a sensor unplugged. OEM ACDelco pads do include new sensors which acccounts for some of the price difference. Jim Drive your car. Use your cell phone. CHOOSE ONE ! Link to comment Share on other sites More sharing options...
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