Ibanez GWB35 pickup wiring question

Hey guys, I've got a GWB35 that I am replacing the preamp in. The pickup has 3 wires coming off of it, all bundled in white insulation. A red wire, black wire, and white wire. For the life of me, I have no idea what the colored wires are (positive, negative, ground?) Is there anyone that can shed some light on this for me. I have been online and haven't found anything that answers this. I have also reached out via email to Ibanez and am awaiting a reply, if any.
Thank you for any assistance you can provide.