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 voltage is less than 0.25 volts on APP 1. |
| • | 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 22°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.
A scan tool reads APP 1 position in volts. It should read about 0.45 to 0.95 volt with the throttle closed and the ignition ON or at idle. Voltage should increase at a steady rate as the throttle is moved toward Wide Open Throttle (WOT). Also, 90% pedal travel is acceptable for correct APP operation. Scan the APP sensor while depressing the accelerator pedal with the engine stopped and ignition ON. Display should vary from about 0.74 volt when throttle is closed to about 3.7 volts when throttle is held at the Wide Open Throttle (WOT) position. A DTC P0122 will result if the signal or reference circuits are open.
Test Description
The number(s) below refer to the step number(s) on the Diagnostic Table.
-
This step determines if P0122 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 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? | -- | ||
Is the APP 1 voltage less than or equal to the specified value? | 0.25V | |||
3 | The DTC is intermittent. If no additional DTCs are stored, refer to Diagnostic Aids. If any additional DTCs were stored, refer to those table(s) first. Are there any additional DTCs stored? | -- | Go to the Applicable DTC Table | Go to Diagnostic Aids |
Is the APP 1 voltage greater than the specified value? | 4.75V | |||
5 |
Is the APP 1 voltage greater than the specified value? | 4.75V | ||
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 1 signal circuit open or shorted to ground? | -- | ||
9 | Check the APP 1 sensor signal circuit for a poor connection at the PCM and replace the terminal if necessary. Did the terminal require a replacement? | -- | ||
10 | Check for a poor electrical connection at the APP module and repair if necessary. Was a problem found? | -- | ||
11 | Replace the APP module. Refer to Accelerator Pedal Position Module Replacement . Is the action complete? | -- | -- | |
12 | Replace the PCM. Important: The new PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | -- | |
13 |
Does the Scan Tool indicate the diagnostic Passed? | -- | ||
14 | Does the Scan Tool display any additional undiagnosed DTCs? | -- | Go to the Applicable DTC Table | System OK |
