Hi thank you for your question hope this helps.
P0480 Cooling Fan 1 Control Circuit Malfunction
P0483 Cooling Fan Rationality Check Malfunction
P2509 ECM/PCM Power Input Signal Intermittent
Lets start with the P2509, this is a vary common problem with the 03 cummins. There is a vary easy fix to it, A bad ground at the intake heater Is the # XXXXX cause of this code along with in some cases causing stalling because the computer sees a power drop this causes the computer to stop the engine.
Check the ground wire on the side of the intake heater remove and clean both the wire connector and the intake heater.
This is a pic of my intake air heater this is with the air tube off but hope you get the idea.
Now As for the fan speed issue, (P0480, P0483) check the wires going to the engine fan. I have read a few cases where they get pulled apart. Also check that the fan clutch
is in working order.
I would worry about the P2509 first it could be the ground condition that caused this.
Fix the P2509 bad ground then clear the cods and drive around if the fan cods cum back we can go from there.
Hope this helps