stsbank Posted August 27, 2010 Report Share Posted August 27, 2010 Earlier today i noticed that when the brake pedal is pressed to make a complete stop, there is a hissing sound coming from behind the pedals. I don't know from where exactly. at home, i checked it out with the car on park then pressed on the brakes and notice the rpm's go up a bit. then it dies. the pedals are hard to press. what might be going on here? Link to comment Share on other sites More sharing options...
stsbank Posted August 27, 2010 Author Report Share Posted August 27, 2010 forgot to mention. this only occurred once and does not happen every time i hit the brakes. Link to comment Share on other sites More sharing options...
BodybyFisher Posted August 27, 2010 Report Share Posted August 27, 2010 Earlier today i noticed that when the brake pedal is pressed to make a complete stop, there is a hissing sound coming from behind the pedals. I don't know from where exactly. at home, i checked it out with the car on park then pressed on the brakes and notice the rpm's go up a bit. then it dies. the pedals are hard to press. what might be going on here? I would look into your vacuum booster unit for the hard pedal and hissing, but I dont know what is causing the stall when you hit the brakes Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
JimD Posted August 28, 2010 Report Share Posted August 28, 2010 ....but I dont know what is causing the stall when you hit the brakes Yes you do know! A large vacuum leak like a ruptured brake booster will stall the engine. Jim Drive your car. Use your cell phone. CHOOSE ONE ! Link to comment Share on other sites More sharing options...
stsbank Posted August 28, 2010 Author Report Share Posted August 28, 2010 Where should I be looking to find the problem? Where is the vacuum booster unit? Link to comment Share on other sites More sharing options...
Cadillac Jim Posted August 28, 2010 Report Share Posted August 28, 2010 The vacuum booster unit is on the firewall in the engine compartment directly above the brake pedal. -- Click Here for CaddyInfo page on "How To" Read Your OBD Codes-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data -- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC Yes, I was Jims_97_ETC before I changed cars. Link to comment Share on other sites More sharing options...
BodybyFisher Posted August 28, 2010 Report Share Posted August 28, 2010 ....but I dont know what is causing the stall when you hit the brakes Yes you do know! A large vacuum leak like a ruptured brake booster will stall the engine. , of course I do, its sort of like pushing up on the EGR valve, but my brain did not kick in.... thanks Jim Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
stsbank Posted August 29, 2010 Author Report Share Posted August 29, 2010 Thanks guys for the quick responses. Its a pretty large piece is there anything "special" about the R&R or is this job pretty straight forward? Link to comment Share on other sites More sharing options...
WarrenJ Posted August 29, 2010 Report Share Posted August 29, 2010 Does your cruise control work? The bracket at the brake pedal contains an electrical switch which disengages the cruise control when the brake is applied. As a safety backup there is also a vacuum switch on the bracket which vents cruise solenoid vacuum to the atmosphere to defeat cruise control in the event the electrical switch fails. It's about the only thing I can think of that would produce a vacuum "hiss" at the brake pedal. I've never heard of a cruise vacuum solenoid stalling the engine even if it's completely ruptured, but there's a first time for everything. There is no means of avoiding the final collapse of a boom brought about by credit expansion. The alternative is only whether the crisis should come sooner as the result of a voluntary abandonment of further credit expansion, or later as a final and total catastrophe of the currency system involved. - Ludwig von Mises Link to comment Share on other sites More sharing options...
stsbank Posted September 5, 2010 Author Report Share Posted September 5, 2010 I got the brake booster from a local scrap yard for 25 dollars!!! Swapped them out yesterday but the brake lights stay on. How can the switch for the brake pedals be adjusted? I know its the lower one but dont want to break it. Link to comment Share on other sites More sharing options...
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