My '89 has not had operational abs since I bought it in 2007. As many other things didn't work, it was low on the priority list of fixes. Finally got around to troubleshooting.

Most of the troubleshooting articles (I can post links if needed) mention the probability of the relays causing trouble, followed by wheel sensors, followed by actual components.

First thing I checked was the relays, and found one to be dead. Its the silver Bosch one, 0332205003, or better part number 20623. As the 20623 relay is 60 some dollars, and it is listed in the cross reference catalogs as "bosch relay, 30A, universal," I decided to just wire in a 5 prong fog lamp relay I had sitting around. Although that relay was new, it had a broken coil and I spent the rest of the day troubleshooting around a bad relay. You can purchase a relay similar to this for about $6, my local store didn't have one so I had to pay $12...

Basically, I needed to convert from the old Bosch round terminal plug to the newer standard blade plug. With .157 Bullet male terminals and female blade crimp on connectors I made an extension harness.



Now it works..

Things not to do: notice in this picture I don't have the heat shrink tape over the terminals like in the picture above:



So, after getting everything to work I stuffed the relay away and it shorted on a brake line.... Don't do that.

Relay like:


Old pin style:


Also, there are pre made connectors to attach a relay:



buy those, then these:


and wire it up. Pay attention to the terminal numbers, although on a universal 5 prong 30A relay they did not change (30, 87, 87A,86 and 85)

Initially if I had a working relay bouncing around I could have fixed this for free. Buying the actual Bosch relay new will cost you at least $60 and you will probably have to order it. I plan to scrounge the junkyard for some back up relays, I think 80's volvo's and maybe mercedes/bmw's may have used this relay. Make sure the wires you use can handle at least 30A, and don't let anything ground out!

If you have time to shop, you can pick up a relay for about $6, relay connector for $5 and bullet connectors for about $3.

The other 2 relays are expensive as well, but they can be swapped out too. The main relay is already a flat blade style but it has some diodes to prevent voltage surge with operation, the third relay is a simple 4 prong (round terminal). Spend some time with a relay catalog match up the relay diagrams instead of actual part numbers and you should be ok (check the amperage rating, diode direction). Remember A relay is just a switch, no black magic.

It is so neat having one of the first ABS systems working! I like how it is performance oriented, and not born from safety concerns. Although this will make me more comfortable driving/autocrossing in the rain

 

useful info. thanks

 

Your keyboard is upside doown.

 

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