Wiring a fish finder cable with new head unit plug

Hi everyone

I have an Eagle Fish Easy Depth Sounder, which is attached to a thru-hull transducer. Its actually a pretty terrible bit of equipment, but im trying a quick fix while im stillon the water - ill replace the whole thing next slip.

The plug for the head unit disintegrated, so I ordered a new after market cable. I'm attempting to splice the new plug into the existing cable, but I'm stuck on understanding which wires to splice together. Im new at this so have probably already made a few mistakes!!

The cable splits into two - the first is a power cable with red + black wires - pretty self explanatory. The other cable runs to the transducer and has 4 wires. The problwm is that they have different colours so im not 100% sure whether Im on the right track.

The 4 wires are insulated in pairs. From the new cable there is a black with red and a yellow with pink.from the old cable, there is a black with blue and a yellow with white. Im making an assumption that the yellowgoes with yellow, blavk with black and then from deducing the rest - pink with white and red with blue.

The plug is sealed so I would need to cut it open to see where the wires enter the plug

Any advice would be great! I've never really had a go at this so many thanks for your patience! :)

Unless the plug has completely disintegrated you should be able to connect the multi-meter on a pin at the plug end and match the corresponding color at the other end of the cut cable. Do the same for the new plug and match the position of each pin in relation to the slit or flat section of the plug and you have your color match.
PS. Since they are not all the same color I wouldn't automatically assume that black goes to black and yellow to yellow.

Let us know how it works out, Pat

Gary