Powertrain Controls - ECM/PCM

DTC 26 Accelerator Pedal Position (APP) 2 Circuit Low:

Accelerator Pedal Position (APP):

CIRCUIT DESCRIPTION
The Accelerator Pedal Position (APP) module provides a voltage signal that changes relative to accelerator position. There are three sensors located within the APP module that are scaled differently.

DIAGNOSTIC TROUBLE CODE (DTC) 26 WILL SET WHEN
Voltage is less than 0.25 volt for 2 seconds on APP 1 sensor.

ACTION TAKEN (Powertrain Control Module (PCM) will default to)
The input from the sensor is ignored. A current and history DTC will set but it will not turn "ON" the "Service Throttle Soon" lamp. The throttle will operate normally as long as there is only one malfunction present. If two different APP sensors have a malfunction, the "Service Throttle Soon" lamp will light and the Powertrain Control Module (PCM) will limit power. If three APP sensors have a malfunction present, the "Service Throttle Soon" lamp will light and the PCM will only allow the engine to operate at idle.

DTC 26 WILL CLEAR WHEN
The fault condition(s) no longer exist, and the ignition switch is cycled "OFF" then "ON."

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. This step determines if DTC 26 is the result of a hard failure or an intermittent condition.
2. This step checks the PCM and witing.
3. This will check the PCM and CKT 993.

DIAGNOSTIC AIDS
A Tech I scan tool reads APP 2 position in volts and should read about 4.5 volts with throttle closed and ignition "ON" or at idle. Voltage should decrease at a steady rate as throttle is moved toward WOT.
An open or short to ground in CKT 996 or 993 will result in a DTC 26.
Refer to Intermittents. - Intermittent Malfunctions
Scan APP 2 sensor while depressing accelerator pedal with engine stopped and ignition "ON." Display should vary from about 4.5 volts when throttle was closed to about 1.5 volts when throttle is held at Wide Open Throttle (WOT) position.