Nordstrand NJ4SE ground wires

[shoulderpet]

Just got a Nordstrand NJ4SE bridge pickup for my pj Mustang bass, have wired it up to my Mustang bass and connected the white hot wire and the black ground wire (I have had to reverse this and treat black as hot and white as ground in order to be in phase with the p pickup in this bass) however I noticed that the gray wire which is also supposed to be a ground wire for the pickup poles when I wire this the same way as the black wire (which is supposed to be ground but I have had to treat it as hot in order for the pickup to be in phase with the p pickup) there is a slight roll of of high frequencies compared to with just the black and white wires connected, is this meant to happen? I am wondering if I should be treating the gray as a ground even though I have had to reverse the wires on the white and black wires in order for the pickup to be in phase with the p pickup, any ideas? Thank you

Edited 1 hour ago by shoulderpet

[shoulderpet]

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Edited 2 hours ago by shoulderpet