What function do you want to add? If it’s lighting you’ll need to tap into the common (i.e. the pad that the blue wire is connected to) or another common soldering pad. Usually there is more than one common on a decoder board.
So the harness for the Lok 5 uses white for the speaker??? That’s confusing. [:^)] White is usually the (+) for F0F headlight and brown wires are speakers. I don’t see any brown wires
And it looks like you also have a green AUX wire. That gives you two options for lighting or other functions.
Interesting. It still makes it confusing using multiple white wires (and right NEXT to each other [:S]). But…as long as you can keep it straight. The schematic is also a mirror image of the photos. Maybe the photo is reversed?
So, it looks like there is only one (-) common pad on the above board. You can either solder a 2nd common wire to that…or solder one directly onto the Lok5 decoder.
Here’s the schematic showing where the other “U+” commons are located on the 8-pin versions:
The downside to the latter is that you would need to unsolder the common from the Lok5 in order to completely remove the decoder from your locomotive. Not a big deal but a consideration, nonetheless.
