Circuit Description
The Accelerator Pedal Position (APP) module provides a voltage signal that changes relative to the accelerator pedal position. There are three sensors located within the APP module that are scaled differently. This is a type D DTC.
Conditions for Setting the DTC
| • | The voltage is greater than 4.75 volts on APP 1 sensor. |
| • | The condition was met for 2 seconds. |
Action Taken When the DTC Sets
| • | The input from APP 1 sensor is ignored. |
| • | This DTC will not turn on the Service Throttle Soon lamp by itself. |
| • | The throttle will operate normally as long as there is only one malfunction present. If there are two APP malfunctions present, the PCM will turn the Service Throttle Soon lamp ON and limit the power. If a third APP malfunction is present, the Service Throttle Soon lamp will be ON and allow the engine to operate at idle only. |
Conditions for Clearing the MIL/DTC
| • | A History DTC will clear after forty consecutive warm-up cycles during which the diagnostic does not fail (the coolant temperature has risen 5°C (40°F) from the start up coolant temperature and the engine coolant temperature exceeds 71°C (160°F) of that same ignition cycle). |
| • | Use of a Scan tool will clear the DTC codes. |
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 0 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 volt when throttle is held at Wide Open Throttle (WOT) position. A P0123 will result if the ground circuit is open or the signal circuit is shorted to voltage.
Test Description
The number(s) below refer to the step number(s) on the Diagnostic Table.
-
This step determines if DTC P0123 is the result of a hard failure or an intermittent condition.
-
This step checks the PCM and wiring.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 |
Important: Before clearing the DTCs, use the scan tool Capture Info in order to record the Freeze Frame and the failure records for reference, as the data will be lost when the Clear Info function is used. Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||
Is the APP 1 display greater than the specified value at a closed throttle or greater than the specified value at a wide open throttle? | 4.75V | |||
The DTC is intermittent. If no additional DTCs are stored, refer to Diagnostic Aids. If any additional DTCs were stored, refer to the applicable DTC table(s) first. Are there any additional DTCs stored? | -- | Go to the Applicable DTC Table | Go to Diagnostic Aids | |
4 |
Is the APP 1 less than the specified value? | 0.25V | ||
5 | Probe the APP 1 sensor ground circuit at the APP sensor harness connector with a test light connected to B+. Is the test light ON? | -- | ||
6 |
Was a repair performed? | -- | ||
7 |
Is action complete? | -- | -- | |
8 |
Was a repair performed? | -- | ||
9 |
Was a repair performed? | -- | ||
10 | Replace the APP module. Refer to APP Module Replacement . Is the action complete? | -- | -- | |
11 | Replace the PCM. Important: The new PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | -- | |
12 |
Does the Scan Tool indicate that this diagnostic Passed? | -- | ||
13 | Use the Scan Tool in order to select Capture Info, Review Info. Are there any DTCs displayed that have not been diagnosed? | -- | Go to the Applicable DTC Table | System OK |
