Need some help with ABS
02-11-2010, 02:22 PM
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Need some help with ABS
No, not my stomach, LOL!
I have an '02 SR5 sport 4runner with 97k on it, 4x4. I bought it used, with 40k on it. I meticulously maintain it. Brakes on it are good all the way around - they are about halfway worn. Since the day I bought it (3 years ago), it's always been quick to engage the abs (I know this is common with 4runners, my '97 did the same thing). But this one always does it in gradual right hand turns (at speed) with light pressure on the brake pedal - I get that "clicking" sound/feeling in the brake pedal. I'm never sure if it's a problem with the VSC or the ABS, but it's definitely one or the other. I've never really done anything about it, as it's never been much more than that, and doesn't cause any other problem. No dash warning lights at all, ever.
In the last month, I've had the need for two panic stops. One was on a wet road, from about 50mph down to zero. The other was from about 20mph down to zero (this one was on rough/uneven pavement). Both were sudden and resulted in HARD applications of the brake pedal, which of course turned the ABS on. I'm not trying to brag or anything here, but I'm a fairly alert and competent driver as far as driving skills go. I've driven all kinds of high horsepower cars and have a lot of confidence behind the wheel in all sorts of driving conditions. I learn new things every day, but I guess I mention it so that you realize that I'm not the average guy behind the wheel that doesn't understand what goes on when I hit the brake pedal. Anyway, I've never been real comfortable with ABS in situations like the ones above. I find that the ABS normally engages too quickly for me, and ends up locking brake/pedal pressure in too lightly/too early...and then leave me feeling as though I'm not slowing down quickly enough. The end result is that I start lifting off the brake pedal to try to stop or disengage the ABS, so that I can reapply the pedal to regain control of the brake system. Sometimes I regain control, sometimes I don't (the ABS stays on).
So back to these two panic stops - during both of them, I attempted to lift up and reapply the brakes for the reasons I just mentioned above. When I did so, the ABS did in fact disengage, but this time, the pedal just went to floor, as if I had lost my brakes completely!!! I had VERY little brake pressure! I actually grabbed for the ebrake on both instances! Luckily I did not hit anything!
Obviously my "techniques" are messing with the ABS system here, but I've driven this 4runner and my old '97 this way for years without any previous problems like this where the pedal has went to the floor...so I have to think that something changed or went bad in terms of an sensor or pump or something? But the ABS system is obviously still working up to the point of me "interacting" with it. Again, I have no dash lights on.
Are there any ABS/VSC experts out there that know this system well enough to know where I might start to try see if I have a problem or how to test to isolate a problem like this? I know if I go to the dealer this will turn into thousands of dollars to just throw parts at it because they'll never be able to replicate the problem. I'm not sure that I can replicate the problem!
Thanks in advance...I know this is a shot in the dark!!!
Mike
I have an '02 SR5 sport 4runner with 97k on it, 4x4. I bought it used, with 40k on it. I meticulously maintain it. Brakes on it are good all the way around - they are about halfway worn. Since the day I bought it (3 years ago), it's always been quick to engage the abs (I know this is common with 4runners, my '97 did the same thing). But this one always does it in gradual right hand turns (at speed) with light pressure on the brake pedal - I get that "clicking" sound/feeling in the brake pedal. I'm never sure if it's a problem with the VSC or the ABS, but it's definitely one or the other. I've never really done anything about it, as it's never been much more than that, and doesn't cause any other problem. No dash warning lights at all, ever.
In the last month, I've had the need for two panic stops. One was on a wet road, from about 50mph down to zero. The other was from about 20mph down to zero (this one was on rough/uneven pavement). Both were sudden and resulted in HARD applications of the brake pedal, which of course turned the ABS on. I'm not trying to brag or anything here, but I'm a fairly alert and competent driver as far as driving skills go. I've driven all kinds of high horsepower cars and have a lot of confidence behind the wheel in all sorts of driving conditions. I learn new things every day, but I guess I mention it so that you realize that I'm not the average guy behind the wheel that doesn't understand what goes on when I hit the brake pedal. Anyway, I've never been real comfortable with ABS in situations like the ones above. I find that the ABS normally engages too quickly for me, and ends up locking brake/pedal pressure in too lightly/too early...and then leave me feeling as though I'm not slowing down quickly enough. The end result is that I start lifting off the brake pedal to try to stop or disengage the ABS, so that I can reapply the pedal to regain control of the brake system. Sometimes I regain control, sometimes I don't (the ABS stays on).
So back to these two panic stops - during both of them, I attempted to lift up and reapply the brakes for the reasons I just mentioned above. When I did so, the ABS did in fact disengage, but this time, the pedal just went to floor, as if I had lost my brakes completely!!! I had VERY little brake pressure! I actually grabbed for the ebrake on both instances! Luckily I did not hit anything!
Obviously my "techniques" are messing with the ABS system here, but I've driven this 4runner and my old '97 this way for years without any previous problems like this where the pedal has went to the floor...so I have to think that something changed or went bad in terms of an sensor or pump or something? But the ABS system is obviously still working up to the point of me "interacting" with it. Again, I have no dash lights on.
Are there any ABS/VSC experts out there that know this system well enough to know where I might start to try see if I have a problem or how to test to isolate a problem like this? I know if I go to the dealer this will turn into thousands of dollars to just throw parts at it because they'll never be able to replicate the problem. I'm not sure that I can replicate the problem!
Thanks in advance...I know this is a shot in the dark!!!
Mike
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