Remove the ecu connector and make sure all the pins are pushed all the way into the connector. Clean the connector with white vinegar. If the wire is loose in the connector, pull it out and bend the little spur out furter so it hangs when inserted. Read the electrical section intro stuff about how to take the wires out of the connector. The 89 fsm has a better section on this than the 90fsm...

A single steady pulse is the indicator of a healthy ecu with no stored codes. Flatline is a dead ecu. Codes are long and short pulses.

The pictured part is one of two components on the underside of the coil bracket that comprise an "LC filter", which conditions the spark signal for the tach. If grounded, that circuit can kill the spark. Use liquid electrical tape to reseal and insulate.