Shift light not accurately reading

[AsleepAtTheTree]

Gen 1 with glowshift shift light not reading right

Instructions say to clip both the orange and brown wire for 4cylinder engines, green wire to tach signal, black to ground and red to power

Is the yellow/blue tach signal under the instrument cluster a good source for the shift light reading or is there a known better source for the gen 1

Thanks for any and all help

 

[Kiwi Rider]

Not sure on this, but someone here may know . . .