Powertrain Controls - ECM/PCM

DTC 23 Accelerator Pedal Position (APP) 1 Circuit Range Fault:

Accelerator Pedal Position (APP):

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

DIAGNOSTIC TROUBLE CODE (DTC) 23 WILL SET WHEN
PCM has recognized a "skewed" (mis-scaled) sensor. The Powertrain Control Module (PCM) compares all three sensors to each other and determines if there is a 6% difference between APP 1 and APP 2 and a 10% difference to APP 3.

ACTION TAKEN (PCM will default to)
The input from APP 1 sensor is ignored. A current and history DTC will set but it will not turn "ON" the "Service Throttle Soon" lamp. Throttle will operate normally as long as there is only one malfunction present. If there are two APP malfunctions present, the PCM will turn "ON" the "Service Throttle Soon" lamp and limit power. If a third APP malfunction is present. the "Service Throttle Soon" lamp will be "ON" and only allow the engine to operate at idle.

DTC 23 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 there is a good 5 volt reference.
2. This step will check for an open in the ground circuit.

DIAGNOSTIC AIDS
A scan tool reads APP 1 position in volts. Should read about 0.45 to 0.95 volt with throttle closed and ignition "ON" or at idle. Voltage should increase at a steady rate as throttle is moved toward Wide Open Throttle (WOT).
Also, 90% pedal travel is acceptable for correct APP operation.
Scan APP 1 sensor while depressing accelerator pedal with engine stopped and ignition "ON." Display should vary from about 0.74 volt when throttle was closed to about 3.7 volts when throttle is held at Wide Open Throttle (WOT) position.