GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The Accelerator Pedal Position (APP) sensors are mounted on the accelerator pedal/TAC module assembly. There are three individual Accelerator Pedal Position sensors within one housing. Three separate signals, a ground, and reference circuits. If only one APP sensor DTC is set, the redundant APP systems allow the Electronic Throttle Control (ETC) system to continue operating normally. This DTC sets if the PCM detects a problem with more than one APP sensor. One APP sensor DTC will not cause the Reduced Engine Power message to be displayed. Two 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 one APP sensor, this DTC will set and the Reduced Engine Power message is displayed.

Conditions for Running the DTC

    • DTCs P0606, P1517, P1518 are not set.
    • The ignition switch is in the crank or run position.
    • The ETC serial data is operational.

Conditions for Setting the DTC

    • Two or more APP sensors are out of range or all three APP sensors disagree or one APP sensor is out of range and the other two APP sensors disagree.
    • All of the above conditions met for less than 1 second.

Action Taken When the DTC Sets

    • The PCM will illuminate the malfunction indicator lamp (MIL) during the first trip in which the diagnostic runs and fails.
    • If equipped with traction control, the PCM will command the EBTCM via the serial data circuit to turn OFF traction control and illuminate the TRACTION OFF lamp.
    • The PCM will store conditions which were present when the DTC set as Freeze Frame and Fail Records data.

Conditions for Clearing the MIL/DTC

    • The PCM will turn OFF the MIL during the third consecutive trip in which the diagnostic has been run and passed.
    • The History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
    • The DTC can be cleared by using the scan tool.

Diagnostic Aids

For an intermittent, refer to Symptoms .

    • If a repair is completed and the DTC was cleared using a scan tool on the same ignition cycle, the default action will not clear until an ignition cycle has occurred.
    • When the TAC module detects a problem within the ETC System the PCM receives a message across serial data and more than one ETC System related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing one individual problem may correct more than one DTC. Keep this in mind when reviewing captured DTC info.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. When the problems are corrected which are causing the APP sensor DTCs to set, the status of this DTC will change to History.

DTC P1125 - Accelerator Pedal Position (APP) Sensor System

Step

Action

Value(s)

Yes

No

1

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

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Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

This DTC indicates that two or more APP sensor DTCs are also set.

Review the DTCs.

Go to the APP sensor DTCs that are set and perform those diagnostic tables.

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