Help, Please, with ABS Brakes on a 1990 SC

Hello guys,

I would really appreciate your input on the following problem(s):

My ARC pressure Sensor has been leaking for a long while now! Every time I braked a little DOT3 stream would shoot out...
I kept ignoring it by refilling the reservoir every month as needed. This is not a daily driver. It's my fun car!
Two weeks ago I was driving, went to use the brakes and to my surprise I had no power assist. The infamous hard pedal experience which was pretty scary! I spent some time on this forum, did some research, and did some troubleshooting and this is what I found:

The ABS pump motor was not coming on with the key on. No lights on in the cluster by the way...
Relays were tested good! I tested them off the car on the little motorcycle battery. The coil(Terminals 1&2 has around 63 Ohms)which is within spec. There is continuity between 3 and 5 with the switch off and continuity between 3 & 4 with the switch on).

I then tested the 4 pin connector of the pump motor and there was no power(positive)there! I put power on terminal 3 of the pump motor relay and immediately I heard the pump motor working! Basically, with the key on I have no ground on terminal 1 of the pump motor relay.
At this point, I suspect the ABS pressure switch! I tried to unplug the connector to do some testing on it but I was not able with my huge hands!
Is there a way to unplug it without having to remove the whole assembly from the car?
Also, is it possible to remove the switch without removal of the assembly?
Also, what kind/size tool do you need for this job?
How do I replace the ARC pressure switch? Do I have to bleed the brakes afterwards?
lastly, where do I find these two pressure switches?(new, used)

I would appreciate your valuable input! I really wanna drive my SC soon. It's been over two weeks now! I am going nuts without it...
Please, HELP this desperate SCer...
Regards,
Gus

I believe your diagnosis is correct....

The ABS pressure switch breaks ground to the pump motor when the proper pressure is reached....

Replacing that switch is a royal pain, however it can and has been done by a few people....

I've found that it is a little more labor intensive to remove the entire master cylinder assembly to service the switch, but not nearly as aggravating as trying to replace the switch with the unit still in the car....

You can also remove just the pump motor assembly (remove the accumulator first) to get to the switch....

I still have a few used pressure switches.....

Give me your zip code and I'll quote you a price that includes shipping....

If you don't mind a hack job, remove inner finder, take a 3" hole saw and make an access opening for the pressure sw. Be careful when doing so as to NOT cut into items behind it. I did this on mine because I really didn't care about keeping the car pristine. I am sure others would not consider this at all, for me I was so tired of working on the brake system I didn't give a rats behind.

Hiram K said:

I am sure others would not consider this at all, for me I was so tired of working on the brake system I didn't give a rats behind.

Click to expand...

Hello Hiram K,

You made me laugh my friend...
I have been considering all my options right now(a. taking the whole unit out, b. make the hole in the fender c. try to do it from underneath, d. give up and do something less frustrating with my life
Thank you though for your valuable input...

Gus

Easiest way is to remove the front seat, lay down, and get to work....

It's only about a 2 - 4 hour job for your first time....

Remove the ABS unit and switch to conventional... You will never have to worry about it again.... I remove and reinstalled my ABS unit like 3 times until I said enough is enough.. Never been happier!!