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
The ignition switch in the on position.
Conditions for Setting the DTC
| • | The voltage is greater than 4.75 volts on APP 1 sensor. |
| • | All 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 is stored 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 the start up coolant temperature and the engine coolant temperature exceeds 71°C (160°F) of that same ignition cycle). |
| • | 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 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 0 APP operation. Scan the APP 1 sensor while depressing the accelerator pedal with the engine stopped and the ignition ON. Display should vary from about 0.74 volt when the throttle is closed to about 3.7 volt when throttle is held at 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
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 the DTCs, use the scan tool Capture Information functions to record the Freeze Frame and Failure records for reference. The control module's data is deleted once the Clear Information function is used. Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
Is the APP 1 above the specified value? | 4.75 V | |||
The DTC is intermittent. If no additional DTCs are stored, refer to Diagnostic Aids. If additional DTCs were stored, refer to the applicable DTC table(s) first. Are any additional DTCs stored? | -- | Go to the Applicable DTC Table | Go to Diagnostic Aids | |
4 |
Is the APP 1 less than the specified value? | 0.25 V | ||
5 | Probe the APP 1 sensor ground circuit at the APP sensor harness connector with a J 35616-200 unpowered test lamp connected to B+. Is the test lamp ON? | -- | ||
6 |
Did you perform a repair? | -- | ||
7 | Check for proper electrical connections at the APP sensor and replace the terminals if necessary. Refer to Wiring Repairs in Wiring Systems. Did you perform a repair? | -- | ||
8 |
Did you perform a repair? | -- | ||
9 | Replace the APP module. Refer to Accelerator Pedal Position Module Replacement . Is the action complete? | -- | -- | |
10 |
Important: The new PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. 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 |
