Adding to the cowl by swapping in at those plugs means the remote control will no longer trim the motor.
You can lengthen those wire to that switch ... just use good technique, good marine butt connectors, AWG tinned wire, and adhesive-lined heatshrink over the connector and you'll be fine.
Red is any 'hot', and to complete the circuit at the connections by the Trim relays, blue = sky = UP, where green = grass = DOWN. See 'typical' schematic.
Strongly recommend you temporarily hoot it up and confirm the operation before you go cutting in the cowl switch.
View attachment 113764
Yes key start and normal controls with trim switch on throttle and at front of boat. The opening for the cowl switch is on the right side when looking from back of boat. I am suppose to get the switch on Monday, so I will try it without hooking up red wire first. ThanksI looked at my motor today and I just have the blue/white wire and the green/white wire plugged in. My red wire is not connected to anything. But I have the cowl switch and the trim switch on the controls at the center console so it might be getting power from the main wire harness. My cowl switch is a little different but the wiring is basically the same. Do you have key start and normal controls for the motor? If so, you probably don't need to hook up the red wire. Which side of the engine is the cowl switch on?
I am wanting to add a trim switch to the cowl of a 1999 force by mercury 40 hp outboard. The part -87-850691/ It has a green wire, Blue wire, and red wire. Can I just unplug the wires and insert these to the nearest plug as shown in the first picture. On youtube someone stated you can’t use those but need to go to opposite side of engine and connect there, Of course the wire on plug is not long enough to go to other side. See switch picture. Then final question where do you plug in the red wire? Again only thing I can find on youtube is to splice it in on other side of engine. I really don’t want to splice it if I can get away without doing that.
Looks good, I wonder if you really needed to connect the red wire or not. I know both my trim switches work without the key in and I didn't connect the red to the cowl switch. You may want to disconnect the red wire and see if both switches still work.