Brake light and low brake fluid light

I have a 2006 Buick Rendezvous CX. Recently purchased. The brake light AND low brake fluid light are on. I topped it off on brake fluid it has not gone down any. The parking brake is all the way up. The dinging does NOT shut off but maybe if your lucky 5 seconds. The brakes are not spoungey. Anybody know what could be wrong. Waiting to barrow floor jack so I can bleed the brakes to see if that is the issue.

I used to own one of these, a 2004 Ultra with every option except self-leveling rear suspension.

Check to see that the brake fluid level sensor in the master cylinder reservoir is plugged in, and will stay plugged in by itself. You *may* need to replace the reservoir to get a new sensor. You *may* need to remove the reservoir to properly clean it. You *may* need the Tech II to reset things. Beyond that - brakes are important and you ought not drive it until after visually inspecting the entire system - MC, ABS motor, lines (hard and soft), calipers.

If you don't drain and fill the brake fluid in the RDV every couple years or more often (annually) it eventually does weird stuff like this.

PS: My wild guess is maybe your RDV was wrecked and the shop did a half-baked job on aspects of the repairs. People I know who have those cars, once they get them 'dialed in' do *not* want to let them go until they are wrecked, thrashed, or worn beyond economical repair.

Every so often, I siphon the old brake fluid out of the reservoir and replace it with new. Every time I do that, the brake light goes on. I tap the side of the reservoir with a small wrench and the light goes out. Try that.

LARRY70GS wrote:

Every so often, I siphon the old brake fluid out of the reservoir and replace it with new.  Every time I do that, the brake light goes on.  I tap the side of the reservoir with a small wrench and the light goes out.  Try that.

I remove reservoir from the MC and use dry gas with no additives and a small shop rag folded over a thin metal bar (for instance one of the old-fashioned stainless  steel windshield wiper refill stiffeners) to clean it and the channel it rides in.  Because it's brakes, and different MC reservoirs differ a little, I don't recommend that people do that -- but I don't mind stating that is precisely what I have done in such a case.

What I might recommend... as inexpensive as the MC reservoirs are, you might just want to replace the reservoir.

Okay so we had to replace 3 calipers because we could not crack the bleeder screw changed the systems brake fluid and we bleed the lines... Worked great for about a week now i am again loosing brakes the longer you sit at a light pedal goes all the way to the floor at this point i am thinking master cylinder but am afraid it could be both the cylinder and booster. Any advice is appreciated

The light no longer comes on either that problem is fixed just dont know whyi keep loosing brakes

Cmilsp wrote:

Okay so we had to replace 3 calipers because we could not crack the bleeder screw changed the systems brake fluid and we bleed the lines... Worked great for about a week now i am again loosing brakes the longer you sit at a light pedal goes all the way to the floor at this point i am thinking master cylinder but am afraid it could be both the cylinder and booster. Any advice is appreciated

That is classic bad master cylinder.

Thank you thats what i thought it was!

Cmilsp wrote:

Okay so we had to replace 3 calipers because we could not crack the bleeder screw changed the systems brake fluid and we bleed the lines... Worked great for about a week now i am again loosing brakes the longer you sit at a light pedal goes all the way to the floor at this point i am thinking master cylinder but am afraid it could be both the cylinder and booster. Any advice is appreciated

Your booster is holding vacuum if after you turn the car off and let it set a while you still have power assist to apply the brakes once or twice.

I agree with Larry (who's almost always right, does not need me to concur...) at this point I'd just replace the MC. I probably would not have replaced those calipers - I'd pull them, replace the rubber parts (seal and piston ring) and as well replace the bleeder screws. Maybe de-rust and paint them also unless they were already painted/coated.

Quote :

i am thinking master cylinder

That's what I'm thinking, too. Been there a few times. It's not an expensive part, and usually straightforward to replace.

Btw, I'm very impressed with Ate master that came OE on the Riviera. That unit performed flawlessly over the life of the car, and I put it though a whole lot of abuse.

AA wrote:

Quote :

i am thinking master cylinder

That's what I'm thinking, too. Been there a few times. It's not an expensive part, and usually straightforward to replace.

Btw, I'm very impressed with Ate master that came OE on the Riviera. That unit performed flawlessly over the life of the car, and I put it though a whole lot of abuse.

+1 that, except I replaced mine at about 150K miles because the pedal would sink slowly when held pressed very hard and I could not find another cause. The replacement from Napa doesn't have that problem, but it is a 'sleeved' Cardone. Has been in about 160K miles.

We replaced the caliper's because one of the bleeders screws broke off. Inside we tried to get it out with easy out ans everything it wouldnt budge which is why we just replaced them.

There is a rubber cap that caps the bleeder. Without it, dirt and water get inside and rust the bleeder shut. Make sure you replace the cap, or if it is missing, get a replacement. My 98 is on the original calipers at 192K and 21 years.

LARRY70GS wrote:

There is a rubber cap that caps the bleeder.  Without it, dirt and water get inside and rust the bleeder shut.  Make sure you replace the cap, or if it is missing, get a replacement.  My 98 is on the original calipers at 192K and 21 years.

+1 that, Larry  

What roasts me is the number of mechanics who will leave these off (or "lose" them), which is why I do my own brakes and figured out how to make a power bleeder.  

If you are missing your rubber caps, they are cheap and easy to get at most any auto parts store, largely as Dorman HELP items.  Or go from car to car at a pick N pull and pull some.  If it is one you frequent and you are buying about anything else, and you show them at the gate, the counterperson is as likely as not to let you have them.

Surprisingly they were all on but the bleeder screw still broke or wouldnt come loose :/

Cmilsp wrote:

Surprisingly they were all on but the bleeder screw still broke or wouldnt come loose :/

Got it.

Did you replace that MC yet?

No not yet havent had the money to do so but i will let you know as soon as i do!

Cmilsp wrote:

No not yet havent had the money to do so but i will let you know as soon as i do!

This one is $27 plus shipping; they are even a little cheaper if you can re-use your current reservoir:

https://www.rockauto.com/en/moreinfo.php?pk=968496&cc=1022050&jsn=930