Pcm....bcm.....??

[GNXdreamin]

which electronic control unit is responsible for giving engine codes? I cycle my key 3 times, and i'm not getting anything, when i should at the absolute least recieve a 55 code. However, when i first turn the key to on position, the check engine light, abs light, and alarm set light momentarily come on, then go out, like it's supposed to. So what particular electronic component controls that? PCM? BCM? or is it something simple, like a relay perhaps?

[jpb53]

PCM controls the check engine light. All the modules talk to each other over the BUS lines. If you want to see if it is working unplug the MAP sensor or the IAC and see if the light will come on.