DTC P1125: Accelerator Pedal Position Sensors Out Of Range Or Disagree: Description

WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2003 GMC Yukon XL, 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, 2003 Chevrolet Suburban, and 2003 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The Accelerator Pedal Position (APP) sensor is mounted on the accelerator pedal assembly. The sensor is actually 2 individual APP sensors within 1 housing. Two separate signal circuits are used in order to connect the accelerator pedal sensor assembly, and the Throttle Actuator Control (TAC) module:

A 5-volt reference circuit.
A low reference circuit.
A signal circuit.

If only 1 APP sensor DTC is set, the redundant APP systems allow the TAC system to continue operating normally. This DTC sets if the Powertrain Control Module (PCM) detects a condition with more than 1 APP sensor. One APP sensor DTC will not cause the Reduced Engine Power message to be displayed. 2 APP sensor DTCs for the same sensor also will not cause the Reduced Engine Power message to be displayed. However, if two or more DTCs are set involving more than 1 APP sensor, this DTC will set and the Reduced Engine Power message is displayed.