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.
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 0.23 volts (The PCM compares a pre-scaled voltage (internal to the PCM)). |
| • | The difference between APP 1 and APP 3 is greater than 0.50 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 Service Throttle Soon lamp will not illuminate when one APP DTC sets. The PCM will only illuminate the Service Throttle Soon lamp when multiple APP DTCs set. |
| • | The PCM records the operating conditions at the time the diagnostic fails. This information stores in the Failure Records. |
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 0.45 to 0.95 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 0.74 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 numbers below refer to the step numbers 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 any DTCs, use the Scan Tool Capture Info to save freeze frame and failure records for reference, as the Scan Tool loses data when using the Clear Info function. Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to A Powertrain On Board Diagnostic (OBD) System Check | |
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 tables 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. Refer to Connector Repairs in Wiring Systems. Did the terminal require replacement? | -- | ||
8 |
Was the APP sensor ground circuit open? | -- | ||
9 | Replace the APP module. Refer to APP Module Replacement . plete? | -- | -- | |
10 | Replace the PCM. Important: The new PCM must be programmed. Refer to PCM Replacement/Programming . Is the action complete? | -- | -- | |
11 |
Does the Scan Tool indicate the diagnostic Passed? | -- | ||
12 | Does the Scan Tool display any additional undiagnosed DTCs? | -- | Go to the applicable DTC table | System OK |
