Is this due to the Voltage differances? The Tach info describes two differant 4cyl setups, 1: 2pulse , 2: 1pulse . Also where did you find info for PIN descriptions at? I have searched every msg board, search engine, and magazine looking for any info detailing a wire diagram or electronic diagram.and make sure you set up the tach like its a 4 cylinder. It'll work then.
4. There is a white tach wire in the harness - located by the PCM. This is a small 16-gauge wire and it provides a tach signal. Remember to check your tach operators’ manual for proper installation. The white signal wire is a 1-cylinder trigger signal. On Autometer Tach the white signal wire is a 4-cylinder trigger signal and you may need to clip two colored looped wires at the rear of tach for proper RPM reading.