[StuckInKansas]

I have been studying my wiring diagram in preparation for wiring my gear indicator, and I can't figure out which wire(red or blue) is the tach feed into the instrument cluster. I am 99% sure that one is the tach feed and the other is either info. or a power wire. Both come out of the ECU, and go straight to the instrument cluster. Also(totally unrelated), I can't figure out how the hell the ignition switch turns on the instruments and the ECU. The only thing I can figure out is a possible plug that has some jumper wires that is plugged into the factory alarm harness. This is driving me CRAZY! :wtf:

 

[Devious2xs]

The tach feed into the instrument cluster is CAN bus - don't mess with this.

You can get a tach signal from the coil wires or from the crank position sensor.

 

[Decosse]

Similarly with the speedo - use the sender output (pink/yellow wire - goes to A21 on ECM) rather than an input to the instrument.
Then you can use the green/pink wire (which is coil # 1) for the tach (comes from B29 on ECM) & the neutral switch is black/white (goes to A19 on ECM) .