 |
|
|
1985-1998 [Subscribe to Daily Digest] |
 | [Main 9000 Bulletin Board | BBFAQ |
Prev by Date | Next by Date | Post Followup ]
Member Login / Signup - Members see fewer ads. - Latest Member Gallery Photos
Connections Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Tue, 6 Jan 2009 17:07:17
In Reply to: Thanks ari, I've read dozens of your ABS posts..., gavin, Tue, 6 Jan 2009 14:44:50 Members do not see ads below this line. - Help Keep This Site Online - Signup |
There are only four contacts used in the switch. One set is used for the Brake Fluid light, the other set is used for the ABS light.
Pins 4 (white) and 3 (black) are used for the brake fluid light. Pins 3-4 will be connected for a low fluid level, and open for a normal fluid level.
Pins 2 (blue/white) and 1 (blue) are used for the ABS; the are open for low fluid level, and connected for normal fluid levels (yes, opposite of the brake fluid light.)
Simply disconnect the connector - located right under the reservoir. The ABS light will come on - that is normal. If the Brake Fluid light goes out, then the problem is the level switch. If the light stays on, it isn't the level switch.
The brake fluid light turns on if:
(1) The key is in the Lamp test position, when all dash lights should be on.
(2) if the fluid level switch shows a low level -see the note above.
(3) if the ABS pressure is below 105 bar. The ABS light should be on at that time.
You seem to have conflicting evidence to a bad ABS accumulator. The accumulator has a diaphram with pressurized nitrogen gas on one side, brake fluid on the other. When the ABS pump runs, the fluid flows into the accumulator, compressing the gas. The fluid comes out of the reservoir, so you see the level DROP to full. This pressure is used for the ABS and brake boost. When you stomp the pedal, some of the pressure us used up. When the pressure drops below 140 bar, the pump starts running. If you keep stomping, you can use up pressure faster than the pump can replace it -when the pressure drops to 105 bar, the pressure switch turns on the Brake Fluid and ABS lights.
When the accumulator dies, the internal diaphram has failed and the accumulator has filled with fluid. Fluid doesn't compress. So stomping the pedal drops the pressure really fast, and you get the ABS and Brake Fluid lights on after just a few pedal presses.
So with a bad accumulator, the ABS pump has nowhere to push the brake fluid. So typically you don't see the brake fluid level drop very much when the pump runs. You are seeing a big change in brake fluid level - it should be right near the top when the accumulator is fully discharged - as hitting the brake pedal 20 times with the system off will do. Pressurizing it drops it to the right level. So the right amount of fluid is being pumped, which doesn't point to a bad accumulator.
Just to repeat - if you start the car and wait for the ABS pump to stop running - a few seconds after the ABS & Brake Fluid lights go out, how many stomps does it take to make the ABS light come on? (We know the brake fluid light is wonky.)
Unplug the connector at the very front of the master cylinder (radiator side) at the base of the reservoir, the one with four wires. If the Brake Fluid light goes out, the level switch is bad. The ABS light will come on, no problem.
posted by 192.249.4...
, Tue, 6 Jan 2009 11:44:08, Tue, 6 Jan 2009 17:07:17 <-- Viewing This Message, Wed, 7 Jan 2009 08:51:04, Wed, 7 Jan 2009 21:15:32
, Thu, 8 Jan 2009 15:32:05, Thu, 8 Jan 2009 17:53:32, Thu, 8 Jan 2009 11:59:24, Thu, 8 Jan 2009 17:46:53, Tue, 6 Jan 2009 15:53:28
No Site Registration is Required to Post - Site Membership is optional (Member Features List), but helps to keep the site online
for all Saabers. If the site helps you, please consider helping the site by becoming a member.
 |
 |
 |
 |
 |
