Double tap

 

I am also having passenger side headlight issues, replaced bulb, this didnt fix it, replaced ballast, no luck either, but when i did replace ballast i used the pre-exhisting power cable (as it is a pain in the *** to get out the actual head light) and just plugged the old one into the new ballast with new bulb. Any ideas? wondering if its a ground issue or if I should suck it up and exchange power supply cable as well?

 

Rather than throwing parts at the car hoping something will fix it I strongly recommend just swapping components one-at-a-time from one headlight to the other until you isolate what the bad part is.

You can also test the harness for correct voltage/ground using a digital multimeter. Steps are in the FSM section EXL - Exterior Lighting, wiring schematic is around page 88.

https://www.nicoclub.com/infiniti-service-manuals