Here's a few things you may want to check out:
#1 Do you have pickup color codes wired up correctly. If using SD or other color codes pickups don't work as designed. DiMarzio's color codes are:
Red wire - hot output
Black/white - coil split, soldered together whether used split or not
Green/bare - ground
Check your pickups with multimeter to check if they give you correct reading. You can check normal DiMarzio kOhm readings from their website.
#2 Check all the wiring for cold solder joints. Cold solder joints can cause grounding/output issues. Good joints are shiny, bad aren't. Here's a small guide:
https://www.youtube.com/watch?v=E-O2TGoArrY#3 Check your soldering for ground bleed to hot output. This means that if you have a slightest bit of ground touching any output connection you'll get some grounding buzz.
Hope this helps & good luck!