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- Jan 16, 2015
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The resistor is needed for signal development . Some would call it a pull up resistor . There should be 12 V on the speedo pin 4 as well. Without the resistor the pulses waveform would not appear .
There is a test that you could perform ,With a helper and a rear wheel stand . If signal is getting to pin 5 of speedo plug when the rear wheel is rotating you should get a averaging DC level when measured with a DVM. As the pulses increase I would expect the level to increase. If you have an O-scope you can read the pulses directly.