n Transient ImmunityPulse 1 - A simulation of transients due to supply disconnection from inductive loads; it applies to a DUT if as used in the vehicle, it remains connected directly in parallel with an inductive loadPulse 2a - Simulates transients due to sudden  interruption of currents in a device connected in parallel with the DUT due to the inductances of the wiring harnessPulse 2b - Simulates transients from dc  motors acting as generators after the ignition is switched offPulse 3a/3b - Occurs as the result of switching processes. The characteristics of this pulse are influenced by distributed capacitance and inductance of the wiring harnessPulse 4 - The voltage reduction caused by energizing the starter motor circuits of the internal combustion Pulse 4 Variants – Most manufacturer variations of pulse four are generally much more complicated.For example Ford requires up to four arbitrary generators with four outputs to be perfectly synchronized