I just finished the wire tuck on my 93 coupe. Anyway the tachs no working so I looked under the dash (engine harness goes inside) and the blue wire on the engine harness is not hooked into anything. I beleive it got pissed and broke off tugging a little too hard on the wires. Does the blue wire (what you splice for a monster tach) normally go into the grey plug? There is an open space with a little rubber grommet that corresponds with a blue wire (1 white dot) on the grey plug for the interior harness. Sorry if it sounds confusing. I can take a picture if noone understands.