Dodge R1500 1999 Service Manual page 1550

a good injector will be 60 or more volts.
At Point "E", notice that the trace is now just a few volts
below system voltage and the injector is in the current limiting, or
the "Hold" part of the pattern. This line will either remain flat and
stable as shown here, or will cycle up and down rapidly. Both are
normal methods to limit current flow. Any distortion may indicate
shorted windings.
Point "F" is the actual turn-off point of the driver (and
injector). To measure the millisecond on-time of the injector, measure
between points "C" and "F". Note that we used cursors to do it for us;
they are measuring a 2.56 mS on-time.
The top of Point "F" (second inductive kick) is created by
the collapsing magnetic field caused by the final turn-off of the
driver. This spike should be like the spike on top of point "D".
Point "G" shows a slight hump. This is actually the
mechanical injector pintle closing. Recall that moving an iron core
through a magnetic field will create a voltage surge. The pintle is
the iron core here.
This pintle hump at Point "E" should occur near the end of
the downward slope, and not afterwards. If it does occur after the
slope has ended and the voltage has stabilized, it is because the
pintle is slightly sticking. Some older Nissan TBI systems suffered
from this.
If you see more than one hump it is because of a distorted
pintle or seat. This faulty condition is known as "pintle float".
It is important to realize that it takes a good digital
storage oscilloscope or analog lab scope to see this pintle hump
clearly. Unfortunately, it cannot always be seen.
Fig. 3: Identifying Current Controlled Type Injector Pattern