ok we are almost there
so the top pic is the pwm power supply pulsing 28000 times a second into the 12 battery, those combined will be a smooth 12v out.
the way it should work
the bottom picture is the same but with a weak 12v battery that a solenoid pulses between the pulses of the pwm power supply
so the pwm power supply is no help, because it is off at that moment, so your circuit is relying on the 12v battery.
so if your battery cant handle the inrush current of your inductor when it turns on, your circuit can hang at 0 volts until the magnetic field builds in your inductor to reduce the current and have the voltage recover
thats a mouth full
standard electronic stuff
I started clueing into it after my becm died on my 2017 volt, and not becouse it died, but shortly after it, i started to get all these error codes coming up in the car. once that happened i knew that it was the power supply causing this, becouse that what power supplys will do. I been fixing stuff way to long

i know what you are wondering, how can something that is happening that fast, have any effect on any thing.
a light bulb doesnt care
most of the circuit in the car wont care due to the capacitance of the circuit, that allows it to get past those dead short pulses
its the circuits that follow that voltage that fast, that is the problem, little to none capacitance in them
so some of the circuits work and some of them cant and there is nothing harder on electronics than this
becouse now when something is suppose to turn on or off, it cant becouse what controlling it doesnt have the voltage to do it. when the circuit recovers the computers have already sent the command to back something off when the circuit was screwed up, so it was not received and then stuff keeps working when it should be shut off and thing then blows up
do you feel like your back in school

when i realized what was going on, i tryed to get a new battery from gm, they had to order it
so at the same time i ordered a 1 farade capacitor to fix all of this, becouse i knew how hard it was on my electronics and i knew that the new battery would get old and try frying something else later on
so you can see my belva capacitor sitting beside my 12v battery (all in i think it was 56.00 bucks)
got that before my new 12v battery and installed it. all my computers settle down even with the old battery
been over a year and no computer issues
for me its reasonable to believe that the power supply also fried my becm
for the simple reason it followed the same time frame as my battery going bad after a few years
it why i think it has something to do with the bolt batteries as well, same time frame
cant say for sure but i have my suspicions
great, a whole bunch of useless information
how do we fix it