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. This is a type D DTC.
Conditions for Setting the DTC
| • | The ignition voltage is greater than 6.4 volts. |
| • | The engine speed is greater than 300 RPM. |
| • | The difference between APP 1 and APP 2 is greater than .23 volts (The PCM compares a pre-scaled voltage (internal to the PCM)). |
| • | The difference between APP 1 and APP 3 is greater than .50 volts (PCM compares pre-scaled voltage (internal to PCM)). |
| • | There are no in range faults for APP 2 or APP 3 (The PCM checks for high and low voltage faults). |
| • | The conditions 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 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. |
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 start up coolant temperature and engine coolant temperature exceeds 71°C (160°F) that same ignition cycle). |
| • | Use of a Scan tool will clear the DTC codes. |
Diagnostic Aids
There are no driveability issues associated with the APP module unless a DTC is present. The most likely cause of this DTC are poor connections or the sensor itself. The least likely is a PCM problem.
An intermittent may be caused by the following:
| • | Poor connections |
| • | Rubbed through wire insulation |
| • | Broken wire inside the insulation |
A scan tool reads APP 1 position in volts. It should read about .45 to .95 volts 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 .74 volt when throttle was closed to over about 3.7 volts when throttle is held at Wide Open Throttle (WOT) position. The following chart will check voltages on all APP circuits to see if they fall in normal ranges. The PCM compares pre-scaled voltages (these are voltages that the scan tool cannot read). The scan tool reads only output voltages.
Test Description
The number(s) below refer to the Step number(s) on the Diagnostic Table.
-
This Step determines if there is a good 5 volt reference.
-
This Step will check for an open in the ground circuit.
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? | -- | ||
2 |
Are there any APP voltages at specified the values (values are listed as APP 1, APP 2, and APP 3 respectively)? | 0.45-0.95V 4.0-4.5V 3.6-4.1V | ||
3 | 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 |
Is the voltage greater than or equal to the specified value on all of the circuits? | 4.75 V | |||
Is the test light ON (all circuits)? | -- | |||
6 |
Was the 5 volt reference circuit open or shorted to ground? | -- | ||
7 | Check the 5 volt reference circuit for a poor connection at the PCM and replace the terminal if necessary. Did the terminal require replacement? | -- | ||
8 |
Was the APP sensor ground circuit open? | -- | ||
9 | Replace the APP module. Refer to APP Module Replacement . Is the action complete? | -- | -- | |
10 | Replace the PCM. Important: If the PCM is malfunctioning, the new PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | -- | |
11 |
Does the Scan Tool indicate that this diagnostic Ran and Passed? | -- | ||
12 | 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 |
