There will be an ign 12v live when key is on. And a pulsed ground signal from the ecu which opens the injector.

A digital voltmeter may give you an indication of signal when set to dc volts. Depends on it's response time.
deally you want to use duty cycle or pulse width though. Or use an oscilloscope which will give you either of those to verify a signal


http://www.2carpros.com/articles/how...-fuel-injector