Ford Mustang 91 w 5.0l no start relays clicking engine control module (ECM) power and ground check

Description: This 91 Ford Mustang 5.0 had a no start condition, with the fuel pump, WOT, and EEC relays making an intermittent clicking sound. The fuel injectors were not pulsing. Also the ignition coil was randomly producing a sparking sound from inside the distributor cap. No check engine light, scan tool irratic. I first removed the passenger side kick panel, and then unhooked the neg battery terminal. Then loosened the 10 mm headed bolt securing the ECM wire harness connector, and then removed the wire harness connector from the computer. I then reconnected the battery, and checked for (Keep Alive PWR) battery power at pin 1 yellow wire at ECM harness connector. 12v. And then with ignition switch in run position, checked pin 37 & 57 for 12v battery power from ignition switch (OK). Next, meter set to ohms, pin 40 & 60 to car body or bat neg. for less than 5 ohms resistance. OK. (I know, voltage drop is preferred, but is very primitive vehicle, and I was cutting corners)(With the age, the check engine light was out and several other dash warning lights as well, it was very likely that the ECM was not doing its job). Power and grounds to the ECM we`re established, so a new ECM was acquired. The A9 series I believe, with MAF sensor. Another short cut I took was that normally you would check the resistance going to all of the ECM loads for shorts to power, high resistance etc. ie injectors, relays, aftermarket equipment and general cutting and splicing of wires not original to the vehicle. (But as I say, the ecm was old. It was past its time to fail even on a good day) The battery was unhooked again, a new ECM was installed, with it`s new and improved programming and parts. The battery reconnected, and the vehicle started and ran as advertised. A WORD OF CAUTION about computers, while you can usually get away with unplugging them with the battery connected. NEVER disconnect them with the ignition switch on, as unfavorable results may arise. Hooking jumper cables up to a car with a dead battery and the ignition on is a good way to buy yourself another computer as well. Have replaced several computer because of this scenario from customers testimony. Take your time and evaluate the impact of your next course of action, and you will have more favorable results.