Just to share with you fellow v70, s70 c70 friends. My daughter's 98 v70 suffered a brake issue today. She said the pedal went nearly to the floor before she could stop in traffic. At the same time, the Brake warning light illuminated indicating low fluid. I went to pick her up and sure enough the m/c was very low on fluid and there was fluid dripping under the car but the m/c and ABS unit were dry. I filled up the m/c and nursed the car home.

Had my Wife sit in the car and press on the pedal. Fluid began pouring out of the pressure switch that screws into the lower part of the Master Cylinder. Went to the dealer for a new switch. What?? Discontinued...no help. no one in town has one. Online retailers show the part as NLA. Finally found one NOS switch online and ordered it. This little switch has rendered the car undrivable until I can get the switch in hand in a couple of days. The scary part is how quick the part failed and just about emptied the M/C in a matter of 5 miles 1/2 hour of use.

Fortunate circumstances and good headwork on your part. Good to hear daughter is safe and hope she has her car back soon.

I wonder, since the pressure switch is NLA even from Volvo, does this indicate a common failure item and the supply is now depleting? For the rest of us, might have to research what options there are for a replacement switch and/or master cylinder. Don't know that I'd want to trust one found in Pick n Pull.

This is really bad news for some of us. When the weather warms up it will be time to scour the pick&pull yards for a pressure switch. The pictures on FCP do not show a new pressure switch attached to a new M/C.

I did find a NOS:

http://store.voluparts.com/9173210-pressure-switch/

for $64 + S&H

Interesting find, read both pages:
https://ozvolvo.org/discussion/2762/brake-master-pressure-switch-96-850/p2
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Keeping it running is better than buying new

Just a fyi... This particular master cylinder pressure switch is not on our 2000 V70. Looks like Volvo changed to a different switch design for 1999 and 2000 models.

Hi,
Just wanted to update you guys. I received and installed the switch last night. Works like a charm. You do loose a bit of brake fluid so if you choose to replace, I would fill the reservoir to near the top prior to unscrewing the switch unless you want to bleed the system afterwards. put a supply of rags below the switch and unscrew with 14mm open end or flare spanner. be read with the new switch to immediately screw back in. I spend a little time cleaning all the brake fluid off the electrical connector and the lower engine bay where it sprayed from the original event. all in all 30 minute job ⎥ of which was clean up]. Works a treat.

BTW, the 99 and 00 switch was revised with a different type of electrical connection but as far as I can tell it is NLA as well.

Hi Klaus,
Yes, that is where I found the sensor. I actually phoned to make sure he had them in stock and he said yes I have a handful.

As for our OZ friends using a Ford p/s switch...no thanks on a braking system. Also the Ford m/c pressure switch was to deactivate the speed control and it was recalled due to leaks and fire hazard..again no thanks.

It would be nice to find a "generic ATE" sensor as I am sure either ATE or Bosch were oem supplier of the sensor but I had no luck going that route.

Yeah, I find it to be a problem that no replacement is available for something that is really necessary to make the vehicle functional. I am not absolutely sure what the brake system module is doing with the pressure sensor information. It appears that TRACS uses it in the ongoing algorithm and perhaps cruise control does too.
I figure similar switches exist as other cars from the era used some too but the Volvo part number doesn't cross reference to anything I can find [generic? Bosch, ATE, etc.]. A threaded plug could be fashioned, I suppose, but not knowing exactly everything that the sensor is integrated with would make that a risky proposition.

I suppose the new one I have could last 20 years like the first one but who knows.... and my daughter was lucky this time...I don't want there to be a next time.