The banner above is an advertisment - if it asks you to download software, please ignore.
Site News - 7/1: Members: Log In to See Fewer Ads! | 5/28: SAAB Evolutions/TSN T-Shirts $14
[General | Members | C900 | 9000 | NG900 & OG93 | 93 | 95 | NG95 | 99 | Sonett | Vintage Models | Clubs | Other Cars | FAQs | Gifts | Member Photo Galleries | Member Directory | Classifieds | Manuals | *Buddy Registry | *Mileage Registry | Polls | What's New | Raffle | Photo of the Month | Sponsors]

9000 Bulletin Board
1985-1998 [Subscribe to Daily Digest]
(Search Author's Posts: e.g. Keyword:username)*Members Only

[Main 9000 Bulletin Board | BBFAQ | Prev by Date | Next by Date | Post Followup ] Member Login / Signup - Members see fewer ads. - Latest Member Gallery Photos
Re: 1990 9000 brake question
Like This Post: - Subscribe to Daily Digest for this Bulletin Board
Posted by Ari [Email] (#2847) [Profile/Gallery] (more from Ari) on Tue, 14 Oct 2003 10:52:12 Share Post by Email
In Reply to: 1990 9000 brake question, Aaron Rosenstein, Mon, 13 Oct 2003 21:42:27
Alert me when someone posts in this thread:
Members do not see ads below this line. - Help Keep This Site Online - Signup

The ABS does indeed use high pressure hydraulic fluid to work. That same hydraulic pressure is used to provide brake boost.

The accumulator (sphere mounted on top of Master Cylinder) stores the pressure. When the brake pedal is pressed, that fluid comes out to provide brake boost, and it flows into the reservoir. If the pressure in the accumulator drops below 140 bar, the ABS pump runs, and pumps it back up to 180 bar (and the pump shuts off).

When the car is off, the pressure in the accumulator normally leaks down, and again, the fluid goes into the reservoir.

When the car is started, a bunch of things happen. First, if the ABS pressure is below 140 bar, the ABS pump runs. The ABS system also runs a bunch of self tests.

If the ABS system pressure is less than 105 bar, BOTH the ABS AND Brake Fluid lights are on.
If just the ABS light is on, then the ABS system pressure is above 105 bar, and the system is still going through self-test, or it has failed self-test.
Normally, when you first start the car after it has been sitting, you get Both the ABS and Brake Fluid lights, as the pressure has dropped while sitting. After a few seconds (as much as 45 seconds), the Brake Fluid light should go out; the pressure is now over 105 bar. The ABS pump will continue to run for a while, to get to 180 bar. The ABS light will be on for a few more seconds as it finishes self-test.

What it sounds like with your car is that the ABS pressure isn't proper. This is usually due to the ABS pump not running. When the car has been sitting a while (off), open the hood, and note where the Brake Fluid level in the reservoir is. It should be well ABOVE the FULL line. Normally, when the car is started, you'll hear the ABS pump run (humming), and the brake fluid level will drop as the pressure in the accumulator builds up. When the accumulator is fully charged, the fluid will have DROPPED to the FULL line. Seems backwards, but that's how it is.

There is a pressure switch (140 bar), that triggers the ABS Pump Relay, that runs the ABS pump. A problem in any of those systems, and the ABS pump won't run. It can also be a bad high-pressure (180 bar) switch, as it shuts the pump off. It can be as simple as a bad connection, a faulty relay, etc. Yes, it could be a bad ABS pump, which is very expensive. But it can also be cheap.

This doesn't take a computer to diagnose. It takes the ABS schematic, a voltmeter, and some basic troubleshooting skills. The schematics are available in the Brake manual, and also available in the Saab Electrical Supplement. If the Townsend site is up (http://www.townsendimports.com), you can find the schematics there.

If the ABS pump isn't running, then jumper the ABS relay (in the engine compartment) ON, and see if the pump runs. If the pumps runs, then the most expensive part is working.

posted by 192.249....
Posts in this Thread:
Alert me when someone posts in this thread:
Members do not see ads below this line. - Help Keep This Site Online - Signup
Post a Followup

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.

Name: Member Login / Signup - Members see fewer ads. - Latest Member Gallery Photos
E-Mail: (Optional)
Re-Enter E-Mail: (Confidential & Secure - Not revealed to other users!)
Note: Please check your spam folder for BB responses.

Subject:

Posting rules are simple - No for sale/wanted ads may be posted here - use the site classifieds.
You may not cross-post your message to multiple BBs.
Not permitted: political/religious topics and being disrespectful (personal attacks, insults, etc...).
 Site Members do not see any red text, inline ad links, bottom of page anchor ads, box ads, or anti-spam check.

Message: (please no for sale/wanted classifieds - post those in the Saabnet.com Classifieds)
Links are now automatically made active, no need for any special code (or use the Option Link field below) - don't put links in () or end with a '.'
To add inline images to your post, use [img]http://www.domain.com/img.jpg[endimg] (or use the Optional Image Link field below).

Links are now automatically made active, no need for any special code (or use the Option Link field below) - don't put links in () or end with a '.'
To add inline images to your post above, use [img]http://www.domain.com/img.jpg[endimg] (or use the Optional Image Link field below).
Optional Link: (e.g. http://www.saabnet.com/)
Link Title: (Optional)
Optional Photo/Image Link: (e.g. http://www.saabnet.com/img.jpg)
Photo/Image to Upload: (Please be patient while file uploads)



StateOfNine.com
SaabClub.com
Jak Stoll Performance
M Car Covers
Ad Available

The content on this site may not be republished without permission. Copyright © 1988-2024 - The Saab Network - saabnet.com.
For usage guidelines, see the Mission & Privacy Notice.
[Contact | Site Map | Saabnet.com on Facebook | Saabnet.com on Twitter | Shop Amazon via TSN | Site Donations]

Random Saabnet.com Member Gallery Photos (Click Image)
This is a moderated bulletin board - Posting is a privilege, not a right. Unsolicited commercial postings are not allowed (no spam). Please, no For Sale or Wanted postings, SERIOUSLY. Classifieds are to be listed in The Saab Network Classifieds pages. This is a problem solving forum for over 250,000 Saab owners, so expect to see problems discussed here even though our cars are generally very reliable. This is not an anything goes type of forum. Saabnet.com has been a moderated forum since 1988. For usage guidelines, see the Saabnet.com Mission and Purpose Page. Please remember that you are not anonymous. Site Contact | Site Donations | Other Sites by SP - Poverty2Prosperity.org | Run Club Menlo Park | ScreenBot


Site Members do not see red text instructions, bottom of the page anchor ads, or box ads.
Click here to see all the Site Membership Benefits!