Originally Posted by nissan
I have a 1997 toyota land cruiser. I had a rear brake line go bad,so I replaced all the rusty lines to the back and blead them, the back brakes have good pressure,the front has weak pressure and the pedal is real low. I replaced the front calipers and still no change. I blead all the lines at the ABS and master cylinder, nothing changes. the man at the auto parts says it's not the master cylinder if I have good pressure at the back. where else do I look?. what else can be done? can I bypass the ABS system without computer problems? thank you for any help you can provide.
The simple way to test the master is to get some plugs and one at a time remove the lines from the master and install the plug. If the pedal does not get better with the plugs in then the master is bad. The guy at te parts store doesn't know what he is talking about. In a dual master cylinder there are two sets of cups and one can certainly go bad while the other is good. It is common to ruin a master if you blow a line because the cups are pushed into an area they normally do not get to and there is usually some sediment there.
Plug the port and see how the pedal is. Also check for small leaks where you repair the line. This can also cause the issue you are experiencing.