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Re: ABS Wooes, can anybody help Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Tue, 11 Mar 2003 08:18:13
In Reply to: ABS Wooes, can anybody help, M, Mon, 10 Mar 2003 23:06:02 Members do not see ads below this line. - Help Keep This Site Online - Signup |
When the ABS AND Brake Fluid lights are on, that means the ABS pressure is low. That ABS pressure is used to provide brake boost, so no with no boost, you get very high pedal pressures and lousy braking distances.
There are two major possibilities - the ABS pump isn't running when it should, OR the accumulator is bad.
To test the accumulator - Let the car sit overnight. Open the hood and check the fluid level in the brake fluid reservior. It should be well above the FULL line. Start the car - you should hear the ABS pump run, and the fluid will drop to the FULL line. If it doesn't drop, then the problem is that the pump isn't running. Wait until the lights go out and the pump stops running, which is a few seconds after the lights go out.
Now, with the engine running, get into the car and hit the brake pedal hard and fast until the ABS and Brake Fluid lights come back on. If it takes only 4-5 pumps, then the accumulator is bad. If it takes 10-15, then that's normal.
If it isn't the accumulator, then you've got to troubleshoot the pump. The pump turns on when the ABS pressure is below 140 bar, and shuts off when the pressure hits 180 bar. If there is a problem with the pressure switches, the ABS pump relay, or the ABS pump, the pump may intermittently not work. This one isn't easy to test, especially if it's intermittent. At least pull the ABS pump relay and clean the contacts. Try and figure when the pump isn't running, and under those conditions, check the voltages at the pressure switches, relay, and pump.
If the ABS pump relay doesn't close, the ABS pump won't run and you won't get pressure. But don't assume that an ABS Fault of a bad relay means you've got a bad relay. The ABS box may assume that if it doesn't see ABS pressure, then the pump isn't running, and it blames the relay when the problem may be the pump. Without knowing a lot more about the diagnostics in the box, always take a fault code with a grain of salt.
I hope this helps some.
posted by 192.249....
, Tue, 11 Mar 2003 08:18:13 <-- Viewing This Message
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