2005 Subaru Impreza WRX 2.5L no start wiring problem

Car question:

I am wondering why this car keeps stalling and when I press the accelerator pedal, the rpm does not move. Seems like it is stuck at idle rpm. So I checked the electric throttle unit and tug the wires and suddenly the rpm started revving up when I played with it. Also, my scanner gave me this throttle fault code P0607 and I thought this part is the problem. Changed the part but after that, the engine won't start. Also I cannot scan the code anymore because it won't communicate with the car engine computer. Did I damage anything?

ATS Adviser:

No communication is usually a wiring issue and you can check the vref wires at the ecm if they are present or not. I believe there are 3 of them and you can see it at the engine ecm wiring diagram. If the vref voltage value is not there then this will cause the ecm to cut communication especially if the vref is shorted. To check, disconnect each of the 3 vref wires one at a time while disconnecting the sensors connected to that vref wire.

Do it until all 3 vref wires are tested clear for short and open connection. Next check power and ground supplies to the ecm to find if you have a bad wiring using the power and ground wiring diagram. You can trace the power starting from the ignition switch to the main relay upto the ecm terminals. Ground reading at the ecm must not be higher than 0.250 volt otherwise, ground wire is shorted or open.

Aside from the ecm, this engine uses a low speed bus communication located in pin 10 at the dlc connector of the car. Hook up a voltmeter and measure pin 10 and vehicle ground pin 5 and you should get 5-7 volts at KOEO. If out of this range, disconnect each of the 4 modules except the ecm. You can start with the TCM then followed by abs and airbag modules. If any of the module disconnected returns the normal voltage reading at the dlc, then that module is the problem.

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