[mushroom]

The MFI relay (automatic shut down relay) provides battery voltage to the ignition coil. The PCM provides a ground contact (circuit) for energizing the coil. When the PCM breaks the contact, the energy in the coil primary transfers to the secondary causing the spark. The PCM will de-energize the MFI relay if it does not receive the crankshaft position sensor and camshaft position sensor inputs.