Modern Vespa

Need help from the electric gurus. I have a 72' Sprint V and rewired it with a SIP loom (no turn signals so very straightforward) and added a SIP electronic speedo and SIP switch with aux button to control speedo. As per their instructions, I wired the black/white wire from speedo to #4 which is also were the white wire for loom goes. Anyway, I have rear brake lights, and the killswitch works. The brake light, headlight, and aux switch does not function.

Any chance someone has installed the set up and could offer advice?

I think the remote mode switch (for the SIP speedo) needs to be on its own dedicated circuit. Two wires go to the mode switch, one is black, the other is black with a white stripe. The black wire gets permanently grounded to the frame. When the black/white wire is temporarily grounded to the frame, it will scroll through the different settings on the SIP speedo. So make sure that you have the black/white wire connected to a switch terminal that will be grounded when it's depressed. Also make sure you have the correct switch for your electrical system. The AC and DC switches are different.

EDIT: the SIP conversion switches (for their digital speedos) more or less have two separate "kill" buttons. One is to kill the engine, and the other is for grounding out the speedo's remote switch.

On mine I have the power out of the regulator going into the SIP black box. From there it's all dedicated connectors up to the speedo, nothing connected directly from the speedo to the switch with a bare wire.

The wires that are connected to power/earth are black, red and brown.

The only black & white wire from the speedo is the remote switch as WDC mentioned... this shouldn't be cut as it has a connector on one end and a button on the other.
Unless of course you have a SIP light switch with button, and you don't. Here's mine below - number 4 is an isolated switch.

It looks like I need a different switch to run the aux button or as suggested just use the button it came with. My follow up question to those using the speedo on a non battery 6V system where did your source your positive for the speedo box? It says to combine the brown and red if there is no battery but not sure where to connect that. Perhaps the red wire going to the switch?

Electronics are clearly not my strong suit.

...and instructions are clearly not SIP's strong suit either.

And i think you want 12 volts to successfully power the speedo?

Here's a link to the conversion switch that has the optional speedo button. Sorry that it's in german. For some reason SIP won't let me get english on their website anymore. https://www.sip-scootershop.com/en/product/lichtschalter-sip-conversion-fuer-vespa-50-125-pv-et3-125-vna-ts-150-vba-t4-180-ss-rally_60091300

The power box brown wire connects to a light source (headlight, taillight, or pilot light).

The power box red wire connects to the AC voltage regulator.

It's not all pages... just most. The site was down for maintenance on Sunday for a bit.
If you use Chrome as your browser it has a pretty good built-in translate function. They're abysmal. Like, who ever thought it was a good idea to print the instructions to a wiring diagram for the speedo in black and white!!!?
So many examples of poor (or non-existent) communication that you can't blame on language.

Thanks again guys. I greatly appreciate the help. For anyone installing a SIP speedo on a VLB it's red wire from the box to the red wire on switch, black to earth and brown to headlight wire.