How would one go about making sure that the injector driver of the ECU is functioning as designed?

What kind of signal should be sent at ign on, no start?

 

You will need what is called a "noid" light.They plug into the injector plug & will flash when they recieve a signal from the ecu.
The ECU can be set into test mode to check this.Go to the configuration screen & change "config 04cyl" down to "zero"cyl.The ecu will now cycle through all the injector drivers & coil drivers.
Just a tip.........Pull all plug leads off the engine & fit 4 old plugs into them & ground them on the body while you are doing this.Also don't forget to set the config back to 4cyl when you are done

 

yea a local pars shop should sell single noid lights.... 5-7$ i think your gonna want gm style. basicly its a light with the right plug so it fits in your inj. plug and will turn on(flash) when the ecu send a signal to the inj. to open. I used a noid light to find that a friends grandam had #4 injector getting a full time on (open or 100% d.c.) from the ecu... man that was odd to see