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Re: question regarding ABS. 92 cvt. Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Fri, 25 May 2001 15:05:25
In Reply to: Re: question regarding ABS. 92 cvt., Boomer, Fri, 25 May 2001 12:45:59 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Which light(s) come on during hard braking - Anti-lock AND Brake Fluid, or just anti-lock?
The anti-lock AND brake fluid lights come on if system pressure is too low. If there is some other problem in the ABS system, but the pressure is OK, then ONLY the Anti-lock light comes on.
Pressurization - there are three pressure settings - call them Low, Medium, and High. The Anti-lock AND brake fluid lights are on if the pressure is less than LOW. Medium is the lowest the ABS system wants to run at. High is the max ABS reservoir pressure. I use Low, Medium, and High because I don't remember what the actual pressures are.
When the engine is first started, the ABS reservoir pressure is below LOW, so the Anti-lock and Brake Fluid lights are on. Since the pressure is also less than Medium, the ABS pump runs. The pump runs, pressurizing the system. When the pressure gets above LOW, the lights go out, but the pump still runs. Once the pump hits High, it turns off.
As you drive around, between leak down and using the brakes, the ABS pressure drops. Once it hits Medium, the ABS pump starts running, and keeps running until the pressure hits High, where it shuts off. So the pressure bounces between Medium and High. Since Medium is above LOW, the lights should always be off.
Whew!
According to the manual, when the system drops to Low pressure (Anti-lock AND Brake Fluid lights ON), you have enough pressure left in the system to give you brake boost for about 5-10 more stops.
If the Brake Fluid AND Anti-lock lights are coming on under hard braking, first make sure your level is correct. ALWAYS check the level AFTER the ABS pump stops running. The level in the Brake Fluid tank DROPS as the pump runs. This is normal. If both lights are coming on, that implies that your pressure is low, or the pressure switch is off. You can usually listen for the ABS pump running while idling. Hit the brake pedal a bunch of times to drop the system pressure, and listen for the pump. If the pump starts to run and you don't see the lights coming on, then the pressures are probably OK.
If you have a flaky ABS sensor, you can get a flash of the ABS light (and JUST the ABS light) under hard braking. This is what I think you're seeing.
, Fri, 25 May 2001 12:30:34, Fri, 25 May 2001 15:05:25 <-- Viewing This Message
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