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.
Conditions for Running the DTC
Ignition switch in the On position.
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 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 40 consecutive warm-up cycles, if no failures are reported by this or any other emissions related diagnostic. |
| • | Use of a Scan tool will clear the DTC codes. |
Diagnostic Aids
A scan tool reads APP 1 position in volts. It should read about 0.45 to 0.95 volts 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 0 APP operation. Scan APP 1 sensor while depressing the accelerator pedal with the engine stopped and the ignition ON. Display should vary from about 0.74 volts when the throttle is closed to about 3.7 volts when the throttle is held at the 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 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 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 Accelerator Pedal Position Module Replacement . Is the action complete? | -- | -- | |
11 |
Important: The new PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Is the action complete? | -- | -- | |
12 |
Does the Scan Tool indicate the diagnostic Passed? | -- | ||
13 | Does the Scan Tool display any additional undiagnosed DTCs? | -- | Go to the Applicable DTC Table | System OK |
