wwebb Posted October 9, 2007 Share Posted October 9, 2007 It has finally happened to me, the brake & ABS warning lights came on while driving today. The brakes continued to work OK until I got home, but now they feel mushy. When the car is shut-off, I can hear a cavitating sound coming from the master cylinder area. This feels expensive. Any tips on where to begin? It it cost feasible/wise, to replace the master cylinder assembly with a "standard" master cylinder that does not have the high pressure tank or would that necessitate making changes in the calipers or ABS components, etc. ? Link to comment Share on other sites More sharing options...
Guest radiotradio Posted October 10, 2007 Share Posted October 10, 2007 I wounldn't let it worry you too much yet. I sounds like the acumulator has a leak in its bladder and is leaking down giving you the weird sound. You can buy a new one from GM Parts Direct for about $125.00 including shipping. It is simple to replace and you can do it yourself. Take the Reatta brake test found elsewhere on this site and go from there. Be careful not to over fill your brake fluid. It is down about 1/2 inch or more from the top when filled filled to the proper level. I'm sure others will step in to help you if you provide more information such as that provided in the quite elaborate Teves brake test. Good luck! jack Link to comment Share on other sites More sharing options...
jonlabree Posted October 10, 2007 Share Posted October 10, 2007 I would worry about it. It could lead to the brakes failing.Take the brake test and fix what ever is wrong right away.Others have reported serious problems when their brakes failed. It is like stepping on a brick with little results. Link to comment Share on other sites More sharing options...
Vincent Vega Posted October 10, 2007 Share Posted October 10, 2007 Brake test now. Do not drive. Wally? Anything to add? Link to comment Share on other sites More sharing options...
Guest kennyw Posted October 10, 2007 Share Posted October 10, 2007 Have found that the red brake light also operates the parking brake. If you release the parking brake the light should go off. Most time the switch is loose or bad and the crt screen tells you the brake is still on. Fix, tighter, or replace that switch........The forem says if just the anti-lock light is on you still have [regular] brakes. Just make sure it is not the emergency brake that is keeping the red light on...............ken Link to comment Share on other sites More sharing options...
wwebb Posted October 10, 2007 Author Share Posted October 10, 2007 Based on running the brake test as outlined at Reatta.net, it seems the accumulator is the target of opportunity and I ordered one from GMPARTSDIRECT.COM ($130.45 delivered)--thanks RadioTradio for that tip. The local Buick dealer wanted $250.00. Any secrets for the installation of the accumulator? Link to comment Share on other sites More sharing options...
Guest radiotradio Posted October 10, 2007 Share Posted October 10, 2007 When I said don't worry about it......I meant in reference to his worry of how much it would cost. Anybody with common sense wouldn't trust driving it and would fix the problem. jack Link to comment Share on other sites More sharing options...
Ronnie Posted October 10, 2007 Share Posted October 10, 2007 I believe you ordering the accumulator might have been a little premature. I would investigate the problem further. If both lights stay on all the time and never go off and the pump keeps running, the brake system has a problem other than the accumulator.If the pump keeps running all the time, for some reason it is either not capable of building proper pressure OR the pressure switch is defective and not sensing the pressure and shutting the pump off. If the pressure switch does not sense the correct pressure both the red and yellow light will stay on.If the accumulator is the only part that is defective, the system will take longer to build pressure but once it builds the required pressure the pump will stop running and the lights will go out. Even if there is a hole in the bladder inside the accumulator. Link to comment Share on other sites More sharing options...
wwebb Posted October 10, 2007 Author Share Posted October 10, 2007 TDman, I am a bit confused, are you saying that a leaking accumulator can not cause the pump to continue to run? Link to comment Share on other sites More sharing options...
Ronnie Posted October 10, 2007 Share Posted October 10, 2007 I guess for us to be on the same page you will have to define what you mean by "leaking accumulator" If you mean the bladder inside the accumulator is leaking, my answer would be NO the accumulator can not cause the pump to continue to run continuously. This is the condition I assumed you were referring to. The purpose of the bladder in the accumulator is to separate a pressurized gas in the top of the accumulator from the brake fluid being forced into the bottom of the accumulator by the pump. The pump forcing the brake fluid into the accumulator, compresses the gas to provide a reserve pressure in the brake system even when the pump is not running. When the bladder is broken you lose the reserve pressure but the pump will still shut of when the accumulator is completely filled with brake fluid. The accumulator acts much like a "captive air tank" in a well pump system.If you mean the accumulator has a hole or a bad seal where it screws into the manifold is leaking brake fluid out on the ground, then YES it can cause the pump to run continuously. I never read anything in your post that lead me to believe this was your problem. Did I overlook something?Hope this helps to answer your question. Link to comment Share on other sites More sharing options...
kikikj Posted October 10, 2007 Share Posted October 10, 2007 i had the same problem..buick said it was a abs relay pump switch..24 bucks for the part and a 420 bill from buick to find the problem. my brakes are working but the yellow light stays on.(always did ,without affecting the brakes.) so, my reatta is on the road again. now my screen is fuzzy and jumpy...got a new one...that one jumpy and fuzzy too. i have the silver box that goes at the drivers side on the console (don't know what that is) and i plan to put that in and retest the screens..any advice. also buick said there was not communication from the ecbm in the trunk to the dianogtics, so i also changed that out. any thoughts...the car has 80k miles and runs great until this problem and i will be selling her but want to fix these things first..unless is interested and wants to take over. kat Link to comment Share on other sites More sharing options...
Guest radiotradio Posted October 11, 2007 Share Posted October 11, 2007 It does sound like you may have a bad pressure switch if the lights never go out. A defective switch may keep the pump on if that is the case. A defective pressure switch may also be turning off too early and will not allow the system to charge fully and giving the indication of a bad accumulator when indeed it is OK. The accumulator is like a pressure tank for a home water pump.....it just allows you to draw more water before the pump comes on. A good accumulator will allow you to pump the brake several times before you hear the pump come on again. It is good practice to change your accumulator if it hasen't been done in a number of years, as it is a common failure item. Jim Finn, on this forum, is a good source for a used presure switch. He typically charges about $50.00 or so and guarantees them. You need a thin wall 36mm deep well socket to remove the switch. It is necessary to de-pressure the system by pumping the brake about 20 times before removing the accumulator. Using a large allen wrench, you can then remove the accumulator. You may have to also remove a tubular brace above the accumulator to be able to lift it up. The resevoir fluid level will change about 1/2 inch between a presured and an unpresured system. When the switch and accumulator are operating correctly, it will take about 40 or more seconds for the system to charge. jack Link to comment Share on other sites More sharing options...
wwebb Posted October 11, 2007 Author Share Posted October 11, 2007 THANKS for the tips and details ! I guess I will be ordering a switch. //Bill Webb Link to comment Share on other sites More sharing options...
Ronnie Posted October 11, 2007 Share Posted October 11, 2007 Bill, before buying more parts I would troubleshoot the brake system to pin point the part that has failed. Throwing parts at it until it starts working is going to get expensive.For example; the pressure switch MAY be the problem. But, if you have a worn pump that cannot produce the required pressure (aprox. 2200 psi I believe) then even a new switch will not ever sense the required pressure and therefore will not stop the pump from running and will not turn off the lights.To help you determine what part is actually defective read the following threads that are about troubleshooting brake problems. Maybe it will help you. I'm willing to answer any questions I can to help you out. Brake Test Results Hard Brake Pedal Link to comment Share on other sites More sharing options...
Guest radiotradio Posted October 11, 2007 Share Posted October 11, 2007 If the pump is running all the time, the pump relay may have welded contacts or the pressure switch is bad. The pump relay is about $5.00 at any parts store and is one of 3 relays located on a bracket above the center of the engine near the firewall. Relays are a common cheap problem to repair. The more complete information you provide about your symptoms, the more apt people can help correctly diagnose your problem. Good luck again, you will prevail! jack Link to comment Share on other sites More sharing options...
wwebb Posted October 28, 2007 Author Share Posted October 28, 2007 EPILOG:Symptoms: Brake and ABS lights came on, brakes went soft, brake motor would not shut-off even when key was turned off.Fix: Electrical relay was replaced, brake motor would then shut-off but system was not working correctly--brake and ABS lights still on. Replaced accumulator, system is now working correctly. Thanks to everyone for their thoughts. Link to comment Share on other sites More sharing options...
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