Originally Posted by tpatten
I too saw this but I was actually wondering where the tach cord originates from as I don't really want to tap into my PCM
Since your truck utilizes two coil packs (two coils in each pack). Both coil packs utilize a common power feed. However, each coil pack has two separate grounds (one for each coil) which are routed to the PCM, which in turn controls each coil individually.
If you tap one of these grounds for your tach it would not properly register the engine RPM. You would have to use some type of an adapter designed for DIS with coil packs Click link summit racing parts
However, I believe you can tap the PCM Tach output accomplishing the same thing without the need for the adapter saving yourself about $80.00 dollars.