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, if this or any other emmision related diagnostic does not report any failures. |
| • | 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 percent pedal travel is acceptable for correct 0 APP operation. Scan the 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 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 Info to save 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 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 an J 35616-200 unpowered test lamp connected to B+. Is the test lamp ON? | -- | ||
6 |
Was the APP 1 sensor signal circuit shorted? | -- | ||
7 | Check for proper electrical connections at the APP sensor and replace the terminals if necessary. Refer to Wiring Repairs . Did any terminals require replacement? | -- | ||
8 |
Was the APP 1 sensor ground circuit open? | -- | ||
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 |
