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940 1995 945t low brake pedal or near bottom.

122power

122power

dude
Joined
Feb 20, 2009
Location
Where have all the quad squares gone? VV,Ca
Have a 1995 945t with abs and a low brake pedal. Its pretty much down to the floor. Car still stops fine but the low pedal is supposed to be higher. Previous owner panic braked over some railroad tracks and cycled the abs, since then the pedal has been low. He tried to bleed it to no avail. I have bled the system and even swapped out the master cylinder, bled it and still the same symptom. Booster still assists on braking, no leaks anywhere, I have used a half of a big bottle of fluid bleeding it with the wife pumping. Even bled the lines at the abs pump just for gee whiz. Bled the master at the side ports too. I dont know if I can cycle the abs motor or not? Or maybe the combination valve below the master? I have another 945 NA and know what the pedal is supposed to feel like. This one doesnt give any resistance in the pedal until its near the floor. Any ideas? Im kinda at a loss.
 
I'm not familiar with the Volvo ABS, so take this advice with caution... But the ABS systems I have worked on required you to cycle the ABS pump either during or in between brake bleeding.

I was able to bleed an ABS system after a complete evacuation of brake fluid by filling it back up with fresh fluid and pressure bleeding (manual bleeding works fine too). Without activating the ABS pump the pedal went almost to the floor. To activate the ABS pump I got the car up to speed on an empty road, put two tires off the pavement and slammed on the brakes. This activated the ABS and brought the pedal up a little. I then re-bled the brakes and repeated this process about 3-4 times until the pedal was back up to where it needed to be.

There may be an easier way to activate the ABS pump on your car, but the car I did this on was only possible from a dealer only scan tool.

Use this advice at your own risk!
 
Gonna post in here because my '93 has three inches of travel before engagement and I have been stumped as well. Stops just fine but it really doesn't feel great having to go that far before you feel anything. I also replaced the master, rotors, pads, and pressure bled the whole system. I probably put 2 quarts through there...
 
The ABS pump is powered and probably has a relay. I've jumped 30 to 87 on the ABS relay on a couple of Xratties I put the whole master cylinder and ABS pump from a euro spec cousin of the Xratty called Frod Crossways Frewbie Frew...

Just jumped 87 and 30 and walked around back and cracked the bleeders on the rear first---and that about did it..then just a little crack on the fronts.

jumpering the pump is built in power bleeding...

that may not be the problem of long pedal but that's how ya bleed 'em..
Don't run the pump very long...there OUGHT to be a pressure sensor which is 'spossed to shut the pump motor off when the system pressure is up to whatever it is 75 bar or whatever...
Keep a good eye--maybe a low-rent assistant--on fluid level..
 
Looked at the linkage and pin is there. Even looked at the rod coming out of the booster. I saw the two relays at the and pump under the cover. I wonder if there is a way to cycle it through the diagnostic port, but can try the relay deal. Ill see what happens when i try k jets suggestion too. Thanks guys.
 
My V90 had a lot of travel. Turned out to be a sticky caliper pin. Easy to check, pull the wheel and the two caliper bolts (the ones that hold it to the racket, not the ones that hold the bracket to the strut) and check that they slide freely. Check your pads and rotors while you're there, just cause you can. Pull out the sticky ones, clean them and grease with caliper grease.
I remember a method for bleeding the ABS pump but that was when I had a Honda. I forget it now.
 
sailorbenjamin said:
My V90 had a lot of travel. Turned out to be a sticky caliper pin. Easy to check, pull the wheel and the two caliper bolts (the ones that hold it to the racket, not the ones that hold the bracket to the strut) and check that they slide freely. Check your pads and rotors while you're there, just cause you can. Pull out the sticky ones, clean them and grease with caliper grease.
I remember a method for bleeding the ABS pump but that was when I had a Honda. I forget it now.
Click to expand...

You know how sometimes you bang your head against a wall over some problem for way too long and then the absolute last thing you bother to check ends up being the problem?

Yeah. Seized caliper pin on each side was my problem. And I just had the brakes apart too and somehow didn't notice.
 
Took the wheels off up front and found one stuck pin on one side. Fixed that and re bled system, even bled the master with some hoses into the resevior. Inspected the pad thickness and they are pretty much new front and rear. NO Change. Still the same. Real light or soft pedal first half of travel then it firms up on the bottom of the stroke. Maybe I should swap the booster for the hell of it.
 
122power said:
Real light or soft pedal first half of travel then it firms up on the bottom of the stroke. Maybe I should swap the booster for the hell of it.
Click to expand...

Un-plug the vacuum hose from the booster and try it without vacuum assist to see if it's consistent.

I recently did something dumb and broke a freshly re-conditioned booster. I had just the opposite. Needed two feet on the pedal to pull it up until it got to a certain point and vacuum assist kicked in and made me head-butt the steering wheel. Driving with a booster that randomly provides vacuum assist is a bit of a challenge.
 
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