# What could be wrong with my car brakes? need answer fast! **URL:** \ **Category:** Factual Questions\ **Created:** [January 30, 2009, 2:41am UTC](https://boards.straightdope.com/t/what-could-be-wrong-with-my-car-brakes-need-answer-fast/483667 "2009-01-30T02:41:32Z")\ **Posts on this page:** 18\ **Page:** 1
**Author:** ![Apocalypso](https://avatars.discourse-cdn.com/v4/letter/a/f19dbf/32.png) [@Apocalypso](https://boards.straightdope.com/u/Apocalypso)\ **Post date:** [January 30, 2009, 2:41am UTC](https://boards.straightdope.com/t/what-could-be-wrong-with-my-car-brakes-need-answer-fast/483667/1 "2009-01-30T02:41:32Z")
Ok, so yesterday evening I went on a cigarette run. I notice my brake pedal is very “loose”, offering almost no resistance. I almost sail into another car at a stoplight, but jamming the brake pedal as hard as I could finally stops the car about a millimeter from their bumper. Today, the brake pedal is sinking to the floor with no resistance whatsoever, and taking forever to stop. The brake light came on and stayed on. It normally only comes on when I have the emergency brake engaged (it’s not on). Even being ultra cautious and starting to apply the brake about 3 times the distance to stop I usually apply the brakes at, I’m afraid to drive the car. We’ve been getting a lot of ice and snow lately and my car’s outside all the time. Any hope it’s something cheap and quick to fix? Could it be the brake fluid? Or a frozen brake line? I really don’t know anything about cars, and I have a very limited cash flow. The “car” in question is a 1991 oldsmobile Cierra with about 65,000 miles on it. ---
**Author:** ![Duckster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/duckster/32/1244_2.png) [@Duckster](https://boards.straightdope.com/u/Duckster)\ **Post date:** [January 30, 2009, 2:53am UTC](https://boards.straightdope.com/t/what-could-be-wrong-with-my-car-brakes-need-answer-fast/483667/2 "2009-01-30T02:53:12Z")
[ol] [li] **Stop driving your car. No ifs, ands or butts.** [/li][li]Pop the hood and check the brake fluid levels.[/li][li]It sounds like you have a leak. It could be anywhere in the system.[/li][/ol] Any water in the brake line probably would have shown up earlier as spongy brakes. Your evidence indicates brake fluid loss and not water in the line. \*\*If you continue to drive without checking this out and getting it fixed ASAP, it may become a life and death problem. \*\* There is nothing more important than that. ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [January 30, 2009, 2:55am UTC](https://boards.straightdope.com/t/what-could-be-wrong-with-my-car-brakes-need-answer-fast/483667/3 "2009-01-30T02:55:07Z")
> [@Apocalypso](#): > > Even being ultra cautious and starting to apply the brake about 3 times the distance to stop I usually apply the brakes at, I’m afraid to drive the car. Good - because you absolutely should not drive a car in this condition. > [@](#): > > Any hope it’s something cheap and quick to fix? Possibly, but it certainly must be diagnosed. The symptoms are consistent with significant loss of brake fluid. But it won’t do simply to replace it - you must find out what caused the problem. (Damaged hose? Leaking seal?) ---
**Author:** ![NurseCarmen](https://avatars.discourse-cdn.com/v4/letter/n/5daacb/32.png) [@NurseCarmen](https://boards.straightdope.com/u/NurseCarmen)\ **Post date:** [January 30, 2009, 3:04am UTC](https://boards.straightdope.com/t/what-could-be-wrong-with-my-car-brakes-need-answer-fast/483667/4 "2009-01-30T03:04:42Z")
Happened to me once, I had a '63 Chrysler. I was house sitting my brothers house in the middle of winter, woke up, backed the car up and kind of got hung up on a snowbank, so I put it into drive. Started hitting the brakes a good thirty feet before my sister-in-laws K car, but it was cold and that Chrysler was idling high. Hit her car and drove it right through the garage door. Ended up being the master cylinder. Cost a bit. But I’m glad I didn’t kill anyone, I had no control over that car, if a nephew or an adult would have been in front of that idling car I would have killed them. After hitting the car, putting it into park stopped me. If I had been faster, that wouldn’t have worked. ---
**Author:** ![Apocalypso](https://avatars.discourse-cdn.com/v4/letter/a/f19dbf/32.png) [@Apocalypso](https://boards.straightdope.com/u/Apocalypso)\ **Post date:** [January 30, 2009, 3:41am UTC](https://boards.straightdope.com/t/what-could-be-wrong-with-my-car-brakes-need-answer-fast/483667/5 "2009-01-30T03:41:22Z")
Needed answers fast, got answers fast - thanks for the quick responses! Yeah I definitely am not planning on driving it until the problem is fixed. Fortunately I can walk to work and the store. But, erm, if I can’t drive it, how do I take it to get fixed? 😕 ---
**Author:** ![MsWhatsit](https://avatars.discourse-cdn.com/v4/letter/m/eb8c5e/32.png) [@MsWhatsit](https://boards.straightdope.com/u/MsWhatsit)\ **Post date:** [January 30, 2009, 3:43am UTC](https://boards.straightdope.com/t/what-could-be-wrong-with-my-car-brakes-need-answer-fast/483667/6 "2009-01-30T03:43:48Z")
> [@Apocalypso](#): > > Needed answers fast, got answers fast - thanks for the quick responses! > > Yeah I definitely am not planning on driving it until the problem is fixed. Fortunately I can walk to work and the store. But, erm, if I can’t drive it, how do I take it to get fixed? 😕 Gotta call a tow truck, 'mafraid. If you have AAA service, the tow may be covered. Otherwise, you’ll have to pay for it. Call around to see who has good rates. ---
**Author:** ![Gary\_T](https://avatars.discourse-cdn.com/v4/letter/g/3ec8ea/32.png) [@Gary\_T](https://boards.straightdope.com/u/Gary_T)\ **Post date:** [January 30, 2009, 4:09am UTC](https://boards.straightdope.com/t/what-could-be-wrong-with-my-car-brakes-need-answer-fast/483667/7 "2009-01-30T04:09:59Z")
> [@Apocalypso](#): > > But, erm, if I can’t drive it, how do I take it to get fixed? 😕 A tow is cheaper than a funeral. ---
**Author:** ![J\_Cubed](https://avatars.discourse-cdn.com/v4/letter/j/c6cbf5/32.png) [@J\_Cubed](https://boards.straightdope.com/u/J_Cubed)\ **Post date:** [January 30, 2009, 4:15am UTC](https://boards.straightdope.com/t/what-could-be-wrong-with-my-car-brakes-need-answer-fast/483667/8 "2009-01-30T04:15:46Z")
> [@Apocalypso](#): > > Needed answers fast, got answers fast - thanks for the quick responses! The only way that the thread title could be better is if it had the little Blackberry icon from Facebook status updates… ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [January 30, 2009, 4:26am UTC](https://boards.straightdope.com/t/what-could-be-wrong-with-my-car-brakes-need-answer-fast/483667/9 "2009-01-30T04:26:10Z")
> [@Apocalypso](#): > > … how do I take it to get fixed? Any chance you can find a car-savvy friend who makes house calls? It’s entirely possible the problem is easy to diagnose. Otherwise, as MsWhatsit suggests, you’re looking at a tow - as would likely also be the case were you in a brake-failure accident. ---
**Author:** ![cornflakes](https://avatars.discourse-cdn.com/v4/letter/c/9d8465/32.png) [@cornflakes](https://boards.straightdope.com/u/cornflakes)\ **Post date:** [January 30, 2009, 5:01am UTC](https://boards.straightdope.com/t/what-could-be-wrong-with-my-car-brakes-need-answer-fast/483667/10 "2009-01-30T05:01:47Z")
The brake light on your dash came on because either the lines to the front brakes or the ones to the rear brakes didn’t have enough pressure. The light will not go off until it is reset, but it’s not safe to drive your car even if it does. Get a mechanic that you can trust (Even a **good** shadetree mechanic would be ok for this job) and get the brakes overhauled. ---
**Author:** ![Duckster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/duckster/32/1244_2.png) [@Duckster](https://boards.straightdope.com/u/Duckster)\ **Post date:** [January 30, 2009, 5:30am UTC](https://boards.straightdope.com/t/what-could-be-wrong-with-my-car-brakes-need-answer-fast/483667/11 "2009-01-30T05:30:38Z")
> [@Gary\_T](#): > > A tow is cheaper than a funeral. A tow is also cheaper than losing a lawsuit. ---
**Author:** ![PatriotGrrrl](https://avatars.discourse-cdn.com/v4/letter/p/9dc877/32.png) [@PatriotGrrrl](https://boards.straightdope.com/u/PatriotGrrrl)\ **Post date:** [January 30, 2009, 12:07pm UTC](https://boards.straightdope.com/t/what-could-be-wrong-with-my-car-brakes-need-answer-fast/483667/12 "2009-01-30T12:07:17Z")
There are usually mechanics who will come to you listed on Craigslist. And yes, this is probably something a good shadetree mechanic could fix in your driveway. ---
**Author:** ![brad\_d](https://avatars.discourse-cdn.com/v4/letter/b/50afbb/32.png) [@brad\_d](https://boards.straightdope.com/u/brad_d)\ **Post date:** [January 30, 2009, 4:01pm UTC](https://boards.straightdope.com/t/what-could-be-wrong-with-my-car-brakes-need-answer-fast/483667/13 "2009-01-30T16:01:51Z")
> [@cornflakes](#): > > The brake light on your dash came on because either the lines to the front brakes or the ones to the rear brakes didn’t have enough pressure. The light will not go off until it is reset, but it’s not safe to drive your car even if it does. I’m not familiar with '91 Oldmobiles specifically, but the behavior you’re describing does not match that of any car I’ve worked on. In my experience, the “warning” part of the dual-purpose light\* is nothing more than a fluid level sensor in the master cylinder reservoir. If the brake fluid level gets low enough in there, the light comes on; when this situation is corrected, the light goes out. (As has been mentioned, a low brake fluid situation is not simply an “add fluid and forget about it” kind of problem, though - the cause of the low fluid should be found and corrected.) It would not surprise me one bit to find that some makes (maybe BMW and its ilk), especially of relatively new cars, might have more sophisticated functionality behind that light - but I would not expect that on the OP’s car. But like I said, I don’t know this for sure. - - I know you know this, but just to be explicit and avoid confusion: I’m talking about the red “BRAKE” light on the dash that is lit when either of the following is true: (1) The parking brake is engaged; or (2) a “warning” - the meaning of which we’re discussing above - is merited for the service brakes. ---
**Author:** ![Rocketeer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rocketeer/32/4437_2.png) [@Rocketeer](https://boards.straightdope.com/u/Rocketeer)\ **Post date:** [January 30, 2009, 4:08pm UTC](https://boards.straightdope.com/t/what-could-be-wrong-with-my-car-brakes-need-answer-fast/483667/14 "2009-01-30T16:08:35Z")
On my old Duster (1972, drums on all four wheels), the brake light could also be lit by a pressure-sensitive device which compared pressure in the front and rear brake circuits; if one was higher than the other (implying a leak) the light went on. ---
**Author:** ![The\_Flying\_Dutchman](https://avatars.discourse-cdn.com/v4/letter/t/9fc348/32.png) [@The\_Flying\_Dutchman](https://boards.straightdope.com/u/The_Flying_Dutchman)\ **Post date:** [January 30, 2009, 4:24pm UTC](https://boards.straightdope.com/t/what-could-be-wrong-with-my-car-brakes-need-answer-fast/483667/15 "2009-01-30T16:24:01Z")
> [@Apocalypso](#): > > Needed answers fast, got answers fast - thanks for the quick responses! > > Yeah I definitely am not planning on driving it until the problem is fixed. Fortunately I can walk to work and the store. But, erm, if I can’t drive it, how do I take it to get fixed? 😕 You could fill up the brake fluid reservoir, pump the brakes a few time to get rid of air locks, check fluid levels again, and repeat several times to get an ideal how serious the brake line leak is. It is most probable that you will have no problem in getting to a repair facility. ---
**Author:** ![brad\_d](https://avatars.discourse-cdn.com/v4/letter/b/50afbb/32.png) [@brad\_d](https://boards.straightdope.com/u/brad_d)\ **Post date:** [January 30, 2009, 4:26pm UTC](https://boards.straightdope.com/t/what-could-be-wrong-with-my-car-brakes-need-answer-fast/483667/16 "2009-01-30T16:26:26Z")
Interesting! Maybe the OP’s car _does_ have pressure sensors, then. Would the light go out automatically when the condition was corrected on your old car, or was some kind of specific reset required? ETA: This is in response to **Rocketeer**. ---
**Author:** ![cornflakes](https://avatars.discourse-cdn.com/v4/letter/c/9d8465/32.png) [@cornflakes](https://boards.straightdope.com/u/cornflakes)\ **Post date:** [January 30, 2009, 4:28pm UTC](https://boards.straightdope.com/t/what-could-be-wrong-with-my-car-brakes-need-answer-fast/483667/17 "2009-01-30T16:28:00Z")
> [@brad\_d](#): > > …The behavior you’re describing does not match that of any car I’ve worked on. > [@](#): > > [Pressure differential switch](http://www.motorera.com/dictionary/PR.htm) > A hydraulic pressure-operated switch (often included in a combination valve) which activates the brake failure warning light when one of the brake circuits (in a dual-circuit system) falls due to a system leak and associated pressure drop According to HowStuffWorks, the pressure differential switch is usually part of the combination valve these days. This makes sense from a manufacturing standpoint. Otherwise, they tend to be bolted to the firewall. ---
**Author:** ![Rocketeer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rocketeer/32/4437_2.png) [@Rocketeer](https://boards.straightdope.com/u/Rocketeer)\ **Post date:** [February 3, 2009, 10:54pm UTC](https://boards.straightdope.com/t/what-could-be-wrong-with-my-car-brakes-need-answer-fast/483667/18 "2009-02-03T22:54:09Z")
> [@brad\_d](#): > > Interesting! Maybe the OP’s car _does_ have pressure sensors, then. > > Would the light go out automatically when the condition was corrected on your old car, or was some kind of specific reset required? > > ETA: This is in response to **Rocketeer**. Dunno, the question never arose. 😛