MSD Wiring Help on TFI Terminator X Combos
If you are wiring up a MSD box or another CDI box with your Holley EFI powered Fox Body or SN95 pushrod Mustang then this diagram will help in simplifying that process. Holleys instructions show a few ways to have the MSD box run through the Terminator X system. We have found that having the MSD box is beneficial for added spark, especially for boosted applications but not having to rely solely on the box is the way we like to go. The best reason for this is to eliminate a possible failure and leaving yourself stranded by the side of the road. If you do experience a MSD box failure you can simply unplug the wires going to the coil and plug the factory coil wires back into the coil and the car will be up and running again. This allows the Holley EFI computer to completely control your engine management and the MSD box is there for added spark only.
We highly recommend using MSD part number 8874. This adapter harness makes the process even easier for installation or plugging and unplugging the factory coil harness. With that adapter harness you simply color match each wire, plug in the harness to the coil and the factory coil harness and then terminate the heavy gauge power and ground wires directly to the battery. That is it!
If you do not have the MSD 8874 adapter harness you can still "hardwire" the wires from the MSD box directly to the coil and factory coil harness. This will be okay to do but to keep it serviceable we suggest using spade connectors.
