My grandson's 2015 chevy sonic rs 1.4l lost oil pressure. We just replaced the engine and got it to start. Unfortunately it does not respond to the accelerator pedal. Starts runs and the idle will settle down after a minute or 2, but does nothing when the pedal is pressed. Pulled codes and got P2122 and P2127. That is as far as we can go, our code readers only show tps. Please tell me how to diagnose the pedal assembly and anything else.
Thanks
As this is a drive by wire engine, if the ECU can't trust its throttle position data, it's not going to run the throttle.
This won't be a pedal assembly fault, this is going to be throttle body or wiring. 99% of the time is is a fault inside the throttle body, but the connectors and wiring are fragile and can develop issues. I've seen it where the throttle body lost its five volt reference voltage or its ground.
Ideally you'll have a scan tool that can read TPS voltages/percentages so you can see what the computer is seeing, and go from there.
If it's ever been in a collision or has had major underhood work, barring any scan tool testing or voltmeter testing (always backprobe connectors with a needle, never test the front side of a connector - terminals are fragile!) I'd check the wiring harness anywhere between the throttle body and engine computer for chafe points where it may have rubbed through against the transmission or something.
Two "low" circuits indicate that you've most likely lost 5vref to the throttle body, either in the wiring or with a bad terminal in the connector. Automotive connectors are generally rated for only four connection cycles, you can do damage to them just from unplugging things and plugging them back in.
We had to replace the engine due to a lack of oil pressure. Got the replacement salvage engine started on the throttle body that came with the it. It would not rev, but would idle. Then we swapped to the throttle body from the old engine and had the same result. I observed the tps changing on start up for the ecu adjusting the idle for increases in coolant temp. I do not believe the throttle bodies are bad. This morning I checked the accelerator pedal according to a youtube video, and it checks out fine. I failed to mention in the initial post that there are a total of 4 codes, 2 relating to the accelerator pedal, 1 for the cooling fan system and 1 for the evap system. Using a pin out for the ecu I found (hopefully it is the right one) I will check the harness between the pedal and the ecu. If the diagram is incorrect I will check for the 5vdc at the connector for the pedal. Although now that I think about it that will not tell me anything as that is what the ecu is telling me what is wrong. My best guess is that the ecu has gone bad.
The codes you listed are unrelated to the accelerator pedal. They are TPS codes not APP.
Update finally found the correct diagrams. There is no continuity from the pedal plug and the ecu plug. Either the cables are bad(not feeling this one) or we missed or half assed the connector from the engine harness to the chassis. Does any know where this one is located.
Pete: doubled checked the info on the codes is says the ecu is not seeing the accelerator position sensor.
Final update. First thank you to all that responded. Also thanks to all who read this and said hope he figures it out, the gods of mechanical locomotion heard you. Now what was wrong. found the engine harness to chassis plug and it was one of the move the lever to lock/unlock type and it was not locked. Our bad. to anyone who might need it where abouts, looking straight down on the battery tray it is half covered by the tray.
Thanks again I have my garage back.
That is good to hear!
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