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Re: abs problems Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Tue, 26 Jul 2005 05:30:26
In Reply to: abs problems, mike vanness, Mon, 25 Jul 2005 16:37:25 Members do not see ads below this line. - Help Keep This Site Online - Signup |
You do have an interesting one there.
First question - when you first get into the car on in the morning, after it has sat for a while, if you turn the key to ON, but don't start it, do you see BOTH the Brake Fluid AND ABS lights? You should. Next, before starting the car, open the hood and look at the brake fluid reservoir. The brake fluid level should be well ABOVE the "FULL WITH CHARGED ACCUMULATOR" line. If you don't see the Brake Fluid light, then the bulb is burned out or there is a wiring problem to the bulb. I mention this because your symptoms don't make much sense without the Brake Fluid light, too. If the fluid level isn't above the line, simply note the level.
After you start the car, the Brake Fluid light will go out after a few seconds, and the ABS light a second or two later. That's normal. You may even be able to hear the buzz of the ABS pump. The brake fluid level should be dropping in the reservoir, and once the pump stops running, the level should be at FULL. If it didn't move, then the ABS pump wasn't running, and chances are the lights didn't go out. If the level is low, you need fluid. If the leve is VERY low, you need fluid and may need the brakes bled - too low a level, and air gets into the system.
Some basics - if JUST the ABS light comes on, then the ABS system has detected a problem with itself. It is always running self-tests. In that case the light comes on, but the brakes still act just fine. You just won't get ABS if you stomp the brakes hard on a slippery surface. You'll still brake just as well. If the light comes on, there will be a Fault Code set in the ABS computer - a competent shop can read out the code and tell what is wrong.
The loss of brake boost is different. There is a pump that pressurizes the accumulator (sphere), and that pressure is used to provide ABS capability, AND brake boost (power braking). If the pressure is too low, you should get BOTH the ABS light AND the Brake Fluid lights. If the pressure drops below a certain point, which it does during normal use, there is a pressure switch that turns the pump on. If the pressure drops even lower, a different set of contacts in the pressure switch turn on the ABS and Brake Fluid lights.
If you don't have brake boost, and the lights are both out, that tells me that there is a problem with the pressure switch. It could be a bad switch, or dirty contacts on the connector to the switch. It may even be a bad ground for the switch.
First, find out why the Brake Fluid light isn't coming on. If the bulb is good, then it is definately a problem with the pressure switch or the ground wire to it.
posted by 192.249....
, Tue, 26 Jul 2005 05:30:26 <-- Viewing This Message
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