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ABS resources as of March 2023 Posted by StoicBlue87 [Email]  (#1829) [Profile/Gallery]
(more from StoicBlue87) on Sun, 26 Mar 2023 07:55:59
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I've been fumbling through some braking-performance concerns with my 92 900S in the past few weeks.
I'm driving a recently-purchased 92 900S that has suffered intermittent braking issues related to the ABS system: sudden hard-braking/lack-of-power assist that could appear and disappear randomly. The car has been sitting for more than a year generally unused before my purchase. Based on the previous owner's descriptions, I was wary of the brakes giving me problems but in the first month or two, no problems.
And then suddenly, one morning in stop-and-go traffic, the power assist disappeared.
The 5-pin EV1 electrical connector was battered and disintegrating so I swapped in a replacement connector from a parts-car. But still no power-assist.
A quick diagnosis checklist (from Townsend) helped me narrow down the confusion. The car had a relatively new accumulator so I was searching elsewhere for the problem.
The following is the quick checklist:
1: check all ABS fuses (all 3) in the ABS fuse/relay box on the right wheel-well.
2: Check for power at pump relay large red wire. If no power, find out why. If you have power, jump large red to the large yellow wire. The pump should run.
3: If pump does NOT run check the pump ground. (at the master cylinder assembly).
4: If the pump runs, disconnect the jumper and reinstall the relay, pump brake pedal until hard, turn ignition key on (engine off) and check for 12 V at double blue lead from pump relay; if 12V is present, replace pressure switch, it should have been grounded, assuming a hard brake pedal.
5: If 0 volts try a new relay. Once you get the pump running check accumulator and the rest of the system.
My diagnosis ended with suspicion on the pressure switch. I swapped in a spare pressure switch and suddenly, brakes. (note: you need an authentically DEEP-well 36mm socket to extract the switch). And more interesting, the new switch gave me performance of about 24 fast-pedal-pumps before the warning light would illuminate in the dash while the old switch (when it was working) gave me warning lights at only 4 or 5 fast-pedal-pumps. The ABS pump motor seems to be working less than half as hard before this replacement switch was swapped in.
Out of curiosity in case the replacement switch fails in the coming months or years, the price on these switches seems ridiculous; $500 or more if you can even find a new one. They were apparently so widespread in the auto world that even AC-Delco was making them. But now? Very rare and very expensive.
But interestingly, I DID find a business (based in North Hollywood, CA) that claims to rebuild these switches:
http://www.invasionautoproducts.com
I'm keeping them as an option if my alternate pressure switch starts to fail.
In addition, ABS accumulators are kind of a mystery item for the classic Saab 900. I've jumped on links provided in this forum from previous years when somebody finds a good supplier on eBay and the friend who formerly owned my new-purchase 900 used Amazon for his new accumulator. But these suppliers seem a little short-lived and may disappear soon after offering the part.
I discovered a Bosch accumulator part-number that was used on Mercedes (which was using Teves ABS systems like Saab in the early 90s) and just randomly putting this into a google search turns up five or ten places to buy at pricing ranging from $85-160; there are a lot of sellers including Pelican Parts and Amazon.
The part number:
Bosch 0-265-202-070
Here's one sample link for fcpEuro:
https://www.fcpeuro.com/products/mercedes-sbc-brake-pressure-accumulator-cls500-e320-e500-genuine-bmw-0004302694
I can't verify actual dimensions but I think this info re: Saab possibility came from a European Saab forum or something similar. It certainly LOOKS viable (via the Amazon seller) for an honest attempt but unfortunately I can't provide direct commentary on the fit under the 900 hood. The fcpeuro.com seller says it does work with "classic ABS Saabs."
All of this is meant to provide more info on parts-options for the 900 ABS system.
->Posting last edited on Sun, 26 Mar 2023 09:54:29.
, Sun, 26 Mar 2023 07:55:59 <-- Viewing This Message, Mon, 27 Mar 2023 05:33:43, Mon, 27 Mar 2023 19:28:47
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