Camshaft sensor no 12v

[kammy6000]

Hi, I am new to the forum, so please excuse any stupid questions. My bmw 5x 2014 f15 530d had does not have a 12 volt voltage at the camshaft sensor

Cranks but does not start code 273c00 on ista camshaft sensor no signal

I checked all the fuses. They are fine the battery I don't know how old it is. I just acquired the car, I have checked the 12v wire from the sensor all the way to where it goes into the car at hood
Only shows 3.4volts

1 pin is 5v
Middle pin is ground
3rd pin suppose to be 12v but i get 3.4

Tried new sensor still same

Any help much appreciated

Tried with jump leads and booster pack connected
At battery just cranks

[kammy6000]

so it turns out fuel pump under rear seats is shorted .
positive and negative seem to shorted both are ground this will also throw this code possibly , tried removing relay short still present

where this will be shorting any ideas thanks