ke70 tacho issues. one for the electronics people

[love ke70]

hey there
ive searched so dont bother telling me to go do that

im trying to get the stock 4cyl tacho in my ke70 to work with the 6cyl 1ggte
now i know all i need to do is put a trim pot in and adjust until it reads right
simple right..
well NO!
first up, im using a mallory ignition system so the tach signal comes from that, not the coil. so ive taken a wire, looked on the back of the cluster and worked out which one i believed to be the correct wire for the tach signal
connected that
started car
(the trim pot is already in)
tacho no worky
play with trim pot no good
right
measure resistance on trim pot with muilti meter set on 20K ohm it stays on 0.05. thats not right
disconnect trim pot, adjustment now works fine
weird i think
so i think, right start car tacho should work
oh no it fucking doesnt...typical
so im now at a dead end
has my tacho raped itself?
have i used the wrong pin. if anyone knows for sure which is the right pin in the ke70 wiring that would be great
ive used the black one in the plug closest to the drivers side. it looks the right one
one other thing, i attached the 2 wires for the trim pot just before the tacho rather than on the board, should this cause it to fuck up?
not that it would stop it working once i disconnect the trim pot :S
also, theres no resistance across those 2 wires even when removed from the trim pot
so WTF?!?!?
theres my brain dump
please help

[love ke70]

oops, turns out the tacho was sticking...someone pulled on the needle and that makes them stick a bit
hehe

now ive lost boost grrr :@

[WeekendWarrior]

u mite need check that it is working right because 4, 6, and 8cylinders run off a different pulse rate.it seems odd that it would be working normaly but hey if it works it works