Question

Codes P1500 and P0322 on my 1999 Audi A4 2.8L, what grounds the injectors? The ECM. If so what grounds it

Answer 1

P1500 Fuel pump relay circuit ,electrical malfunction

P0322 Ign / distributor Engine speed circuit , no signal

The ECM uses gound to open and closed the injector, the ECM is connected to a ground and uses ground connection these are known as power ground they are a significant type of gounds. Which is attatched to the engine block.  If there is a no start situation and you have code condition P0322 this is a crank position sensor Audi names this as a engine speed sensor without this signal this will have a no start condition.

Answer 2

P1500 AUDI - Fuel Pump Relay Electrical Circuit Malfunction
Read more: https://www.autocodes.com/p1500_audi.html

P0322 AUDI - Ignition Engine Speed Input Circuit No Signal
Read more: https://www.autocodes.com/p0322_audi.html