2012 PPV Accelerator Pedal and Brake Pedal Sensor Faults

[joefarm]

2012 Tahoe PPV
Suddenly has "ENGINE POWER IS REDUCED" message and the following active faults:
P2127 Accelerator Pedal Position Sensor 2 Circuit Low Voltage
P2123 Accelerator Pedal Position Sensor 1 Circuit High Voltage
C0277 Brake Pedal Position Sensor Circuit Short to Ground or Open

I have a Tech2. I have not been able to clear or further diagnose the faults. Engine starts and runs but will not respond to throttle pedal. I have searched the forum, but I wasn't able to find a similar problem. Since this happened at once, I am doubtful both the brake and throttle sensors failed at the same time. Does anyone have ideas?

 

[Tahoe14]

Maybe @swathdiver can help.

 

[swathdiver]

2012 Tahoe PPV
Suddenly has "ENGINE POWER IS REDUCED" message and the following active faults:
P2127 Accelerator Pedal Position Sensor 2 Circuit Low Voltage
P2123 Accelerator Pedal Position Sensor 1 Circuit High Voltage
C0277 Brake Pedal Position Sensor Circuit Short to Ground or Open

I have a Tech2. I have not been able to clear or further diagnose the faults. Engine starts and runs but will not respond to throttle pedal. I have searched the forum, but I wasn't able to find a similar problem. Since this happened at once, I am doubtful both the brake and throttle sensors failed at the same time. Does anyone have ideas?

Joe, you need to use the Tech-2 and a voltmeter along with the troubleshooting guide to solve this. You can subscribe to it at AllDataDIY and there are others.





The brake pedal position sensor is easy enough to replace but it depends on the code and it is not the reason why the car is in limp mode. The cruise control won't work, anyway, it's enough to diagnose with the Tech-2.

 

[joefarm]

Thank you for your help, @swathdiver
Using your troubleshooting, I found several open circuits between the APP and ECM caused by connector X205 not fully seated. This connector is accessed by removing the upper instrument panel trim. Problem solved!