Rev counter

[steve8274]

i have megajolt on my car and am using megajolt.
on my megajolt, one of the wires says tacho out. think its a blue wire.
i connected this to my rev counter and it works on tickover, but when i rev it, it goes to zero.
i rang etb up and they said i need to connector a 1k ohm resistor or maybe diode (cant remember now) between battery and the blue wire.
i have bought the part from maplins but havent fitted yet, mainly because i dont know how to. its just a piece of thin wire with a thing in middle. not sure how to connect this to battery and wire.
dont know if you have this wire but maybe able to wire your rev counter this way if you know what you doing.
if not, someone else may tell us how to do it
hth
steve