Well, Just got done fixing my Mystique cluster w/tach. Earlier today, I posted that my '99 has no tach wire. So I inserted a wire into the drivers side plug on the cluster so that it would contact pin 8 (the tach signal input). I spliced a length of wire to that and ran it through the firewall and spliced that into the brown/blue wire going into the coil pack...worked, but only hat 1/2 what it should (redline was reading 3250rpm's). Apparently this would only work with an aftermarket tach that's adjustable. So, I looked in my Haynes' manual, and found a tach signal wire exiting the PCM.
So... I ran a new wire behind the firewall insulation to the passenger side of the car. Slide out the power steering reservoir. Unscrew the 10mm bolt holding the PCM connector in. Unsnap the dust cover on the connector (a bit tricky, plus be careful not to damage any wires). Look for pin 56 (white/black stripe). There's pin numbers on the end of the connector, starting with 52 on this row. Take one of those quick-snap splicing things (I have no idea what they're really called) and place it around the white/black stripe wire, then insert your tach wire. Crimp closed, snap on the dust cover, and return the PCM plug to it's original position, bolting it down. Replace the PS reservoir. Start the car and you now have a properly functioning stock tach!
