Thread: Speedo wiring

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  1. #1

    Speedo wiring

    Hi Everyone,

    first time poster here (only just joined up today!) but I've been lurking about these forums for awhile.
    I have found myself in a bit of a pickle recently when i bought a new speedo for my cg125 but found there are only 7 wires on the new unit instead of the 8, which connected to 4 bulbs, on the old. the new speedo has leds in it so i think i may need a current limiting resistor (had some help on a circuit forum) to give the leds a stable current so they don't flicker/blow. I still am not sure how to deal with the odd number of wires and how i hook them up. Anyone familiar with this?
    Here's the pictures of the wiring from the new and old units. The wires concerned are on the far left mid ways up on the diagram.


    speedo wires.jpg

  2. #2

    What instructions did the speedo come with? Your bike uses a cable speedo, Is this one all electronic? I'm guessing it might be from the positive and negative leads.

    A bit more info would be a help, but at the end of the day, I'm not an electrics guy so I can't really be of much assistance.

  3. #3
    Of the 8 wires coming from your old unit, two are green. These are common earths so wire them together. To be honest i had one like this (if it's the sort I think it is, fairly cheap eBay job) for my build and struggled with the turn light. In the end I binned it, bought another one without LEDs and just wired a single green LED for the neutral and fitted it into the headlamp. MOT station did question the lack of an turn signal warning light but as the indicators were mounted high, next to the headlight, you could see them from the riding position. Good luck!


  4. #4
    haha yeah cheap ebay one that's it. i think i know what i'm doing now but i'm waiting on some crimp connectors. I'll let you know how it went when I've done it.

  5. #5
    I use Japanese bullet connectors, you can get them here:

    I'd be interested to know if you got the indicator warning light to work, or if you needed some sort of resistor.

    Cheers, Mat

  6. #6
    I got an electronic flasher relay from It can be used with LED, or incandescent or a mix, and has an option to wire in the warning light so you don't get false flashing on the other indicators... But also they are super helpful, if not a little OTT in explination sometimes.