OK, so we just bought a 2000 Chrysler Town & Country minivan, with 130K miles on it. When we test-drove it, the brake warning light came on, but both Mr. S and the salesperson opined that it was probably just a faulty sensor. The window sticker indicated that the brakes were fine.
Two days and 20 miles after we get it home, I drive it over to a friend’s house, and the first time I hit the brakes on the snow-covered road, GRIND GRIND GRIND. And I could feel a pulsing/grinding in the brake pedal. This happened only when I put the pedal almost to the floor – but every time. Scary stuff, and a little off-putting. We have made an appointment wit the dealer to get them checked tomorrow morning. The dealer says they will “work with us” if a repair is needed. Harrumph, we’ll see.
So tonight I was bitching about this in an e-mail to a friend, and she asked if the van has ABS brakes (why yes it does) and said that this is normal. WTF? I go Googling around, and sure enough, it seems to be true. I totally believe her.
But I’m still thinking, Really?? I mean, REALLY??? That just seems so crazy that normal function would make such a godawful noise and feel like a jackhammer under my foot. And if it’s normal, what about that brake warning light? (I could have sworn that we’ve had at least one other vehicle with ABS.)
Please, if this is par for the course, reassure me. (And save me from looking like an idiot; I was going to go into the dealer tomorrow with guns blazing.)
That sounds more or less like correct operation of the ABS pumps. The action differs slightly between the various manufacturers and the noise/vibration from vehicle to vehicle depending on the position of the ABS unit relative to the passenger compartment. Generally speaking, activating the ABS results in noticeable noise from the hydraulic pumps and valves, a buzzing or pulsing feel in the brake pedal and maybe a chattering noise from the brakes themselves. It’s a pretty violent process really.
That said, it doesn’t mean there’s nothing wrong with your brakes. I can’t distinguish from appropriate and inappropriate noises over the internet, so I say take it in and have them double confirm that all is correct. I say this especially given the warning light epsisode, even though my guess is that the fluid may just be a hair low and/or the sensor in the reservoir cap is being a little goofy.
That sounds like ABS operating. If you need them to operate, you really won’t care about the noise. A lot is going on when the brakes are being pulsed 10 times per second, and yes, it makes noise.
Are the roads covered with snow and ice? Have you checked the tires and shocks? You shouldn’t be triggering ABS all the time, but if your tires are bald or your shocks are bad, it will.
Well, yes, we’re rural here and had snow yesterday, so the roads are a bit slick. I was braking slow and easy as I usually do, not panic braking, but just when I got to the bottom of the pedal range, that was when the grinding started. Braking seems to function OK, and when I took the van out tonight on a short trip, I was able to induce or not induce the grinding at will; that is, eaaaasy braking when approaching a stop produced no grind UNLESS I really stomped on the pedal at the end.
Unfortunately I didn’t think to test the braking on the one short stretch of clear (salted) road.
The tires look good and have good tread. Haven’t checked the shocks, as we’ve only had it for two days, but according to the sticker, all has been inspected and is OK. They said it had had one local owner, and the dealer did all the service.
The dealer is local and we’ve been taking cars to them for service on and off for years. It’s family-owned and Mr. S went to school with several of them. So it’s not like we’ve never dealt with them before; we’re good customers (if infrequent) and I’d like to believe that they were honest about the condition of the vehicle and would like to keep us as customers.
That’s what anti-lock brakes do: they pulse so that they do not lock up. Man, we drive like this 6 months of the year here.
ETA: And it is anything but scary. The brakes will stop you much quicker than conventional brakes, and you don’t even have to think about pumping them yourself: just apply and wait.
yep, that’s the antilock system doing it’s thing, bear in mind though that when the antilock system is pulsing your brakes it can increase stopping distance slightly
Shorter stopping distance is not a design criteria for ABS systems. However on wet or dry pavement the stopping distance will usually be no longer and quite often quite a bit shorter than without ABS.
Once you get into snow, however, things change. In a conventional car, you hit the brakes in the snow, the wheels lock (you have no steering control) a small pile of snow builds up in front of each locked wheel, and you come to a stop. with ABS, the system is designed NOT to let the wheels lock, so you don’t build up that little pile of snow, and your stopping distance in increased somewhat. The most important thing is that while it may take you a bit longer to stop, you can steer, where with locked brakes you cannot alter the direction of the car.
The “grind” you hear is the hydraulic pump moving brake fluid under high pressure through the system. The pulsation you feel in the pedal is completely normal when ABS is active and regulating brake pressures.
The bit I’d query is why you tripped them at all. I don’t have ABS myself but I drove a car with ABS for six months, in slick, then snowy, then icy conditions, and only tripped the ABS once, on some wet leaves. Is there a driving style that involves regular bottoming-out of the brake pedal?
Well, the roads ARE pretty slick right now; it’s packed-down, smooth snow. And I can’t say that I absolutely bottomed out, but I had the pedal down pretty low. IT didn’t trigger right away when I braked, only when I really pressed down at the end of the brake.
Anyway, they said yeah, that’s the ABS. The brake fluid was a bit low, so they topped it off, and I didn’t see the brake warning at all during the 5-mile drive home. I also tested the brakes on a dry road and did not trigger the ABS. So all seems to be well.
When I was learning how to drive, my husband insisted that I screech to a halt and stomp the brake pedal down just so I would know what the ABS felt like - good thing he did too, 'cause if I’d felt that grinding for the first time in a ‘need to stop NOW’ situation I probably would have freaked out and taken my foot off the brake.
I experience that in my minivan as well and for all the world I thought my car was doomed. It does brake fine otherwise. I haven’t been able to get it checked out due to financial disaster on our end, so thank you so much!
The brake pedal shouldn’t have to be depressed so far to trigger the ABS in snow. I would wonder why so much brake pedal travel is necessary. I suspect something is wrong, not with the ABS per se, but with other mechanicals of the system.
I guess you have to look at it like this: if conditions are so bad that my ABS is always coming on, then it must be quite slippery. If it is quite slippery, then I shouldn’t have the opportunity to depress my brake pedal so far, because the tires should be losing traction much sooner. Normally, you have to depress the pedal far to trigger ABS on dry roads. On slippery roads, it just doesn’t seem right the pedal should be able to go that far and that often if it really is slick.
WTF? I go Googling around, and sure enough, it seems to be true. I totally believe her.