Hi, Iím having trouble trying to fit a new electronic speedometer to my Kawasaki W650. The speedometer came with no wiring diagram (canít find any information on it online, its a HARDDRIVE 21-6885) and every different way Iíve tried to connect the speedometer to the speed sensor on the bike, it hasnít work. This has made me wonder whether my speed sensor is working, so I ran some tests but I donít know what the results mean.
This is the speedometer. It did some tests, hooking up the wires to a spare 12V motorcycle battery, I found out what some the wires were, but 2 of them are still a mystery. One of them must be the signal input from the speed sensor, and the other one I do not know. I figured I found the + and - for the speedometer dial because the dial on connection, would whizz round to 140mph and then whiz back, resting at dead 0mph, where as without that connection it sometimes rests at 10-20mph.
This is what my speedo sensor looks like. The speedo sensor itself I think is a halls effect one as there are three wires, indicating that it requires a power supply to operate. There an electrical thing that sits connected between the sensor and the speedo, I donít know what it is, and the wiring diagram for the bike doesnít explain it, so I assume it must be a transformer to step up the weak signal output from the sensor, or a to step down the voltage to the sensor that runs on a lower voltage?
Electrical thing between speedo and sensor:
At first I tried connecting the speedometer and the sensor is various combinations, and then turning the wheel at high RPM first gear to trigger the sensor, hoping to see the speedometer dial give me a speed reading. None of the combinations worked. My test results are recorded here:
So now I thought it might be a problem with my sensor, so I hooked up a multimeter and ran some tests (see diagrams and table below). This surprised me, because I thought the current was supposed to increase the voltage on the output signal, not reduce it. Also note that voltage and resistance on the output signal when the wheel was moving was fluctuating 2.5-3.5V and 40 - 47kOhms. I calculated the current using the formula I = V/R.
- Is this a working / functioning sensor? I canít tell.
- I tried to test the sensor at first with a small filament bulb Iíd taken from the back of a tachometer, which didnít work, and I later read that testing speed sensors with filament bulb can damage the sensors electrics? Maybe I have broken my sensor?
- Also, I donít know if all motorcycle speed sensors are inductive / hall effect, so in theory if you had a speedometer that is looking for voltage change (inductive), and a sensor that is outputting DC same voltage at varying frequencies, it wouldnít work?