i'm running Scrach 1.4

How do i program scratch to turm off/on the GPIO interface pins?

If you mean GPIO on Raspberry PI, check out: ScratchGPIO5. If you mean an Arduino, check out: s2a_fm.

If you mean some other device, please tell us which device you are referring to.

BTW, s2a_fm works with Scratch 2.0 and not 1.4, so it may not meet your needs.