Connecting a Humminbird 997c to a Humminbird 255 VHF for dsc or nema0183

[JLWalleye]

I have the wires needed to make the connection, but there is a wire color issue.
The harness coming from the 997c has 3 wires RED, BLACK & WHITE The harness for the 255s VHF has several wires, 2 of them are marked, 1 is marked GPS +(positive) and the other is marked GPS -(negative).

What wire should be connected to what wire ..........for the correct operation?


All help is appreciated.

I have the books, but the 997 book leaves a lot to be desired.