MSefi.com read only forum (Jan.15,2018)

With a MSD modules, the ignition module wires you need to know about are:

tach signal is a yellow wire (do not use this to feed to pin #24 on MegaSquirt® EFI Controller, it is for a tachometer only),
advance control signal is a white wire,
ground is a heavy black wire,
power is a heavy red wire,
switched 12 volts is a thin red wire,
the coil positive (+) wire is orange,
the coil negative (-) wire is thin black,
the unused VR signal wires are green and violet.

Hall sensor, optical sensor, points: feed the signal directly to MegaSquirt® on DB37 pin #24 by using the Hall sensor circuit described in step #50/52 of the assembly guide.
VR sensor: install and use the VR sensor circuit as described in steps #51/52 of the V3 assembly manual,

Note: If you are using the high current driver circuit to control an ignition module instead of a coil directly (and don't want to use the processor port directly - i.e., you have not jumpered JS10 to IGN), you likely need to to add a pull-up resistor. This allows the signal to go both high and low, rather than floating and low). Also, the IBGT will invert the signal from the processor, so your 'Spark Output' setting will need to be reversed.