help fixing 2 IQ5 FEC 120 pellet grills

You are going to need to test the circuit board components and paths. A digital multimeter will be of great help. If you can identify the individual components with their printed name you can research each for their respective specs.  Other than that maybe a computer repair shop can help.  

I have a DM, and i have downloaded the circuit diagram. I was wondering if the hopper switch could be faulty and preventing the auger from running because i cant see any voltage accross the auger connectors on the board

Check the switch for continuity.

Interesting, the hopper switch on both iq5s works fine when I disconnect them both. But on Hank, where everything seems to come on, the switch is shorted when I connect the cables back to the hooper switch. I can't see if anyone has bypassed it, but I have not looked specifically for that. I am going to check to see if it has 115v accross it.

Just a quick update. But Hank, the IQ5 where the auger doesn't work turns out to be a bad relay on the power board that is sticking. A quick tap with the back of a screwdriver got it working for a short while, but it became stuck again so that needs a new power board. Patsy, the other IQ5 someone, has removed the power board, which will teach me to open up the front and side to check first. The IQ4 with the convection fan not running is a burnt-out motor.  It was a 110v motor, and it had been wired to the 240v side of the transformer. I cut the motor cables, and they measure 240v with the door shut.