Aux Fuel Wiring Diagram for 2021 Mustang EcoBoost HPP

The 4 YELLOW wires with black stripes will tap into the coil pack outputs at pins 45,58, 59, and 60 on the c1551E plug (if you are unsure which one that is, check a couple of pins and confirm the wires match the colors noted below). It doesn’t matter which of the YELLOW wires go to which output, only that they each go to their own output.

The GREEN wire will tap into pin 53 on the c1551E plug. 

The RED wire will need 12 V+ and the black wire will need to be grounded. There are many ways to do this, including using a make-a-circuit to tap into the fuse box.