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 Running the DTC
| • | The PCM performs this DTC diagnostic continuously. |
| • | The ignition switch in the ON position. |
Conditions for Setting the DTC
| • | The voltage on the APP 1 sensor is less than 0.25 volts. |
| • | All of the diagnostic set 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 will store in the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | A History DTC clears after forty consecutive warm-up cycles, if this or any other emission related diagnostic does not report any failures |
| • | The use of a scan tool. |
Diagnostic Aids
There are no driveability issues associated with the APP module unless a DTC is present. The most likely causes 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 percent pedal travel is acceptable for correct APP operation. Scan APP sensor while depressing the accelerator pedal with the engine off and the ignition ON. Display should vary from about 0.74 volt when throttle is closed to about 3.7 volts when the throttle is held at wide open throttle (WOT). A DTC P0122 will result if the signal or reference circuit are open.
An intermittent may be caused by any of the following conditions:
| • | A poor connection |
| • | Rubbed through wire insulation |
| • | A broken wire inside the insulation |
Thoroughly check any circuitry that is suspected of causing the intermittent complaint. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.
If a repair is necessary, refer to Wiring Repairs or Connector Repairs in Wiring Systems.
Test Description
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 the DTCs, use the scan tool Capture Info to save the Freeze Frame and Failure Records for reference. The control module's data is deleted once the Clear Info function is used. Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
Is the APP 1 voltage less than or equal to the specified value? | 0.25 V | |||
3 | The DTC is intermittent. If no additional DTCs are stored, refer to Diagnostic Aids. If additional DTCs were stored, refer to those table(s) first. Are any additional DTCs stored? | -- | Go to the Applicable DTC Table | Go to Diagnostic Aids |
Is the APP 1 voltage greater than the specified value? | 4.75 V | |||
5 |
Is the APP 1 voltage greater than the specified value? | 4.75 V | ||
6 |
Was the 5 volt reference circuit open or shorted to ground? | -- | ||
7 | Check the 5 volt reference circuit for a proper connection at the PCM and replace the terminal if necessary. Refer to Wiring Repairs in Wiring Systems. Did you perform a repair? | -- | ||
8 |
Was the APP 1 signal circuit open or shorted to ground? | -- | ||
9 | Check the APP 1 sensor signal circuit for a proper connection at the PCM and replace terminal if necessary. Refer to Wiring Repairs in Wiring Systems. Did the terminal require replacement? | -- | ||
10 | Check for a proper electrical connection at the APP module. Repair the connection if necessary. Refer to Wiring Repairs in Wiring Systems. Did you perform a repair? | -- | ||
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 |
