I'm trying to work through this code. MIL stays on all the time. No other codes. Did a 'check' of the IPC and can turn on all lights in the IPC and turn them off with my Launch scan tool. Once exiting the test, the MIL is still on. I used a flow-chart for a C3500 as I can't find one for the 4500 and the MIL is supposed to be turned on via a signal on pin 46 of ECM Connector #2. Wiring of this connector looks just like the wiring diagram for the 3500. When removing the C2 ECM connector the light says on in the dash. When I unplug the C1 connector the light will go out. So, the MIL is being turned on by something in connector #1. I was wondering if anyone on here has any ideas. Thank you,
