Possible Causes

WARNING: This page is about a different car, the 2003 Mazda B4000, 2003 Mazda B3000, and 2003 Mazda B2300. However, it is still accessible from the selected car via links, so may be relevant.

Possible causes are:

Coil driver circuit shorted to ground in harness.
Coil driver circuit shorted to PWR.
Damaged ignition coil.
Damaged PCM.
Open coil driver circuit in harness.
Open or short in IGN START/ON (RUN) circuit.