Car Speed Signal Input ? (Enter bigaudiofanat)

[CorbinDallas]

I did a quick search but couldn't find the definite answer to this one. I purchased the Pioneer Avic x940bt and I'm getting ready to wire it up. I'll be doing the "mute" pin/parking brake bypass, but I was wondering if I use the "car speed signal input" wire on the pioneer harness if it will negate the bypass and not let me plug in a nav spot while driving? I've heard this wire gives more accurate results in using the GPS. Will I be able to operate the gps while driving if I use this wire? If it will not affect the bypass I'd like to use it, but just not sure where it goes? Any help would be appreciated!