[L78toLT1]

Originally Posted by arpad_m

I'm not sure about your interpretation, because the diagram indicates open ground by default on 45-48 (bank 1) and 49-52 (bank 0) and an activation switch inside the ECM.

The ECM has several grounds indeed, but they are not specific to injector banks, let alone individual injectors, so that can be ruled out.

How would catch injector pulses with anything less than an oscilloscope when these only last a few milliseconds even at WOT and in fact barely longer than 1ms at idle? I'm no mechanic, but since each injector pulse will only take a small percentage of total elapsed time, I'd think one needs a proper tool to see if the ECM actually sent the signal to fire an injector, you can't observe these fast and short voltage changes or power bursts with normal garage tools.

Believe it or not, just a couple of milliseconds is enough to check with a trouble light. I verified this at the injector on the left side. Since I had an extra fuel rail harness, I was able to do this without removing the blower. I hooked the light to the positive battery post on the fuse box and probed the signal wire on the injector harness while my cranked the motor over. The light flashed away on the left bank.
You state that the ECM has several grounds, but none are specific to the injector circuits, so that can be ruled out. For talking purposes, lets say that the ECM has five grounds, are you saying that if any one, or more of these break down, it could not cause my problem? Just trying to understand, I know your knowledge of all things related to circuits and electronics far surpasses mine!