3 speed switches for off/low/high control for lights

[pn_day]

Dear all,
I ordered 3 speed switches from BMS battery to control front and rear lights, and in particular to be able to switch off the brightest front light when traffic approaches. (Switch is this one: http://www.bmsbattery.com/ebike-parts/53-three-speed-switch-kit.html)

However on testing the connections for them I only seem to have the 3rd position passing current. There are 3 wires (black, blue, red) and the switch is labelled I, II, III.

I know my electronics is rusty, but was expecting position (I) to be off, (II) to pass current between blue and black, and (III) to pass current between red and black.

Currently only red to black with switch at position III passes current (multimeter measuring ohms x10).

What am I missing here?
Thanks in hope
Phil

 

[pn_day]

Doh!
It turns out that the switch operates as follows:

Position I: red and blue closed
Position 2: all open
Position 3: red and black closed.

Just in case any one else is as stupid as me and searches for this!

 

[Deleted member 4366]

Correct, so you can only use it for switching the live. Your bring the battery to the middle (black) wire, and connect one side to the low powered front and the rear lives (two wires), and the other side to the high power front and the rear lives or to all the lights. The negatives go directly to all the lights. You can also put a suitable fuse on the live to the switch, which will protect all the lights.

 

[pn_day]

Agreed, but isn't the red wire the common on this switch rather than the black?

 

[Deleted member 4366]

If what you say above is correct, yes, but normally the black is the common. When it's used as a three speed switch, black is ground, and the switch pulls each of the other two to ground. The CPU senses that and takes the appropriate action.

 

[pn_day]

Thanks d8veh - looks like I've got one that is indeed a common red. Not sure if it is a one off, or if that is the way they are all wired from BMS now.

 

[Deleted member 4366]

I think it's a mistake, but luckily no problem for you.