I have a code P1504 that came up on my truck and I replace the idle control sensor but after replacing it, the code still comes up. I also checked the IAC to see the circuit is bad or shorted out but it is fine.
What else could be possible wrong that the code is still coming up.
One of the wires at the IAC should have battery voltage with the ignition on. The other one controls the ground side of the IAC via the PCM.
If you have battery voltage at one pin and you're positive that the wiring is good between the IAC and the PCM then you probably have a bad PCM.