Dodge R1500 1999 Service Manual page 1565

Fig. 24: Injector Bank - Known Good - Voltage Pattern
EXAMPLE #6 - CURRENT CONTROLLED DRIVER
This known-good pattern from a Ford 3.0L V6 PFI VIN [U]
illustrates that a zener diode inside the computer is used to clamp
the injector's inductive kick to 35-volts on this system. See Fig. 25.