I got the pulse generator. It's revealing some strange results. I have the pulse generator set up to create a square wave with a frequency of 1Hz (one pulse per second) and a duty cycle of 85% (the voltage is high -- about 5Vdc 85% of the time and .25Vdc the rest of the time). I checked it out with my multimeter and it ageed. I also have a data acquisition device called a DataQ DS-194 with software that turns my laptop into an oscilliscope at low frequencies (less than 240Hz). After verifying the pulse generator with the multimeter, I hooked it up directly to the DS-194. The "oscilliscope" showed a square wave cycle that agreed with the above numbers.
Next, I hooked up the circuit Paul provided that contains an external power source and does not connect to the ECM's common terminal. That allowed me to test the entire circuit using the pulse generator and the oscilliscope software without involving the ECM or the softener flow generator. The external power source is a 5Vdc wall wart. I used the 74HC instead of the 74LV due to the higher voltage of the wall wart. This is probably the circuit I would ultimately like to use, including the 5Vdc wall wart. I also added a LED across the pulse generator leads so I could visually see the pulses. The results were the same with and without the LED.
So the results...with pin #3 on the 74HC393N as the output, I saw a "one for one" result on the oscilliscope. Every generator pulse resulted in one output pulse from the 2N3904 transistor. Same frequency, same duration. Pin #4 produced the most erratic output. Sometimes there wouldn't be any pulses for over a minute. When there were output pulses the frequency and duration were very random. Pins 5 & 6 were also erratic and random, but not as bad as pin 4.
I've attached a picture of the circuit. From the left side of the board going counterclockwise, the red lead clipped to the resistor is the positive lead from the pulse generator. The black lead conected to the brown wire is the negative lead from the generator. You can also see the LED between the red and black clips. In the bottom middle...the red lead connected to the yellow wire and the black lead connected to the white wire are from the 5Vdc wall wart. On the right side, the green and yellow leads go to the "oscilliscope". It's hard to see, but the green lead is connected to a gray wire which is connected to the right side of the transistor, which is also jumpered to the ground. The yellow clip is connected to the left side of the transistor. Component-wise, the only thing I was unable to find was a ceramic disc capacitor. I ended up using a multi--layer ceramic capacitor.
So...any ideas what I'm doing wrong?