M-audio pro 88 keyboard

I would suspect the sustain pedal jack on the keyboard is either dirty or defective. Try using some contact cleaner first, and if that doesn't work replace the jack.

Check the pedal first, with an Ohm Meter.
If OK, probably the internal jack is not well soldered to the board, you gotta open the whole thing, get a Tech...

every sustain pedal got different polarity.. normally just go to global setting on your keyboard and change damper polarity setting to plus or minus (select which one work with your sustain padle).

take it into a music store and try a pedal there in store. If it works, buy the new pedal and charge the guests. If it does not work, you know it's th TS input on the keyboard

Assuming this has worked in the past (otherwise if you have changed to different pedal that is the problem) the usual thing is the machine samples the state of the pedal at power up and assumes the polarity of the pedal is at rest. Make sure you are not pressing it as you power up. Also verify the pedal is COMPLETELY plugged in... sometimes they are not quite fully in and that causes a problem, especially with the two stage versions that are sometimes used.

sustain is typcially a product of the sound you have chosen, If you have a sustain pedal you can sustain any sound. you may also have some choices on the switches that allow special sustain, but I dont own a casio keyboard (I have yamaha) but they are nearly the same in operation. The easiest way to get controllable sustain is by plugging in a sustain pedal

Make sure you are plugging it into the place for the sustain pedal. If you happen to plug it into the audio out it may kill the sound.

If the pedal is a simple switch, and not a MIDI device, then most probably the only difference is that in one pedal the switch is wired so it is normally open, and in the other normally closed.
Modifying that would involve disassembling the pedal and looking if the switch can be rewired the opposite way.

Usually that indicates that the polarity of the jack for the sustain pedal has been switched or someone has substituted another pedal with the wrong polarity. Try looking in the manual to see if that is an editable parameter for people who might not be able to obtain an original pedal. You may have to initialize the keyboard which is on page viii of the manual. The jacks on the back for footswitches are on page 1 and 2. The footswitch settings are on page 9. I found the manual here:http://soundprogramming.net/manuals/Ensoniq_KT-76_KT-88_Manual.pdf I don't know if you have the single footswitch or the optional stereo footswitch. If it is the single footswitch, the default setting should work correctly if it is the original SW-2 or SW-6 pedal switches. If it is the optional SW-10, the FTswL setting should be Unused. Hope this helps.

What I figured out is that when i turn on the keyboard, if i hold down the pedal by accident, it will work in reverse. I dont know if this is what you mean. If it is, just dont touch the pedal when you turn it on. If it isn't, try to return the pedal. I dropped one, it had this problem, and they gave me a new one. Your cord for it might have been bent (?). Also, turn the keyboard on with the pedal already plugged in. It's not made to be plugged in while it's on. Hope this helps. - Matthew