Speedo not working

[18lstroup]

My speedo has been clitching out for the last 15 hours or so. Reading rite for a bit then just freaking out reading random numbers. The past 2 hours it just started reading 0. So far I have checked the connection behind the headlight and added electrical grease. Changed the battery in the speedo. Inspected the speed wire and couldn't find anything obvious. The magnet is still on my rotor. What's my next move? A new speedo wire?

[aj_mariner]

Do you have a multimeter?

Speed pickups for tachs that I have worked on in the past generate a small voltage that varies with rpm. The higher speed you mentioned in your last post is odd. If it was just going to zero randomly then I would only be thinking about a chaffed wire or poor connection. The higher than normal speed makes me think it’s randomly picking up voltage from another wire. Have you checked the wire to the display/indicator? Or the connection on the back of the display/indicator?

[Darkside]

Yes, my speedo is doing the same thing. I did notice that while riding if I tug and jostle the cable running up from the sensor it sometimes reads correctly. This leads me to think it might be the connection behind the headlight. I haven't investigated any further yet

[18lstroup]

I have checked every possible plug and connection behind the headlight. Found nothing wrong. Yesterday with my bike the whole way off I was messing with the wire right wear it screws into the brake caliper and it would make my screen light up.

[Hubert Carpet]

Usually, the pickup is a reed switch that is normally open and is closed momentarily each time the magnet passes by. The distance between the switch and the magnet can be adjusted by the number of turns you screw the pickup into the brake caliper.

The switches are pretty fragile and can be damaged when you fit or remove them. They can also randomly pack up.

You can test by unplugging the lead and using a meter or continuity tester. Pass a magnet by the switch or spin the front wheel and check that the circuit is made each time the magnet passes by. Conversely, you can do a quick test on the speedo by briefly shorting across the pickup lead and watching the speedo reading. Not very scientific but will confirm that the speedo is not dead.

If the spare part price for the pickup is too high you can often find them on eBay as plain reed switches.