jackb_ms Posted July 11, 2003 Share Posted July 11, 2003 I have a tacho with a mind of it's own! The needle varies from 0 to 6000rpm in a blink of an eye and it's not me pressing the accelerator. I would like to know if someone had a similar problem and which part i need to change. Which is the most likely to be damage? the tacho or the sender unit? Jack Link to comment Share on other sites More sharing options...
Chris W Posted July 11, 2003 Share Posted July 11, 2003 Jack Check the integrity of the connections on the back of the tacho. The relevant ones are in a multiway plug. Green is +12v, black is ground and black/white is the input. If you have a K series engine then the black/white goes back to ECU pin 55. You would need an oscilloscope to check that the pulses out of the ECU are correct. (They should be approx +6v square wave pulses at twice the engine speed). If your tacho is connected to the coil, check the integrity of that connection too. Depending on the model, you may find other connections on the back of the tacho for shiftlight, illumination, ignition light, high beam and indicators but none of these will affect the tacho operation. If all the connections seem OK and you are able to check out the pulses into the tacho and they too seem OK then the tacho itself has a fault. Chris 2003 1.8K SV 140hp see it here Link to comment Share on other sites More sharing options...
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