79' 318 ecu is live

1....Check spark at the coil tower and do NOT use the in place coil wire. "Rig" a wire and test gap using solid wire, even if low voltage wire, "hung" away from metal

2...Remove dist. connector. With key "in run" tap the bare terminal of the end opposite the distributor to ground. Each time should make one "SNAP" spark

3...With key in "run" measure some voltages

Voltage from coil + to ground should NOT be "same as battery," but much lower, perhaps 6--10V

Voltage from coil NEG to ground should be low, perhaps 1/2--2V or so.

Remove dist. connector. Rig your meter to the distributor connector terminals, set on low AC volts. When rotating, the dist should generate about 1 volt AC

Remove dist cap, inspect cap for dirt, moisture, or tracking at cap terminals. Examine rotor for condition and for possibility of "punch through" of high voltage through the rotor

Examine shaft for wobble or wear, and condition of reluctor for strike damage, or rust and debri.

Continuity of pickup coil should be open/ infinity to dist. case, and ?? about 200 ohms across the two. This is a disputed figure and varies with coils and is NOT A SURE TEST but shows the coil is not OPEN.

Examine all ignition system connectors, the ballast, the ECU, and distritutor. Work them in/out several times to scrub the terminals and to "feel" for tightness. Examine with a light for corrosion.

THERE IS NO good way to test the box, other than if you have eliminated other possibilities, replace it. IT MUST BE GROUNDED to operate