Circuit Description
The accelerator pedal assembly contains 2 accelerator pedal position (APP) sensors. The APP sensors are mounted in the pedal assembly and are not serviceable. The APP sensors provide a signal voltage that changes relative to the position of the accelerator pedal. The powertrain control module (PCM) supplies a separate 5-volt reference and low reference circuit for each of the APP sensors.
The APP sensor 1 signal voltage increases as the pedal is depressed, from approximately 1 volt at rest to above 4 volts when fully depressed. The APP sensor 2 signal voltage increases as the pedal is depressed, from approximately 0.5 volt at rest to more than 2 volts with the accelerator pedal fully depressed.
If the PCM detects that the APP 1 signal voltage is too high, this DTC sets.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P2123 Accelerator Pedal Position (APP) Sensor 1 Circuit High Voltage
Conditions for Running the DTC
| • | The ignition is ON. |
| • | DTC P2123 runs continuously. |
Conditions for Setting the DTC
The APP sensor 1 voltage is more than 4.85 volts for less than 1 second.
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
The Diagnostic System Check - Vehicle prompts the technician to complete some basic checks and store the Freeze Frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.
-
This step tests for a short to voltage on the APP sensor 1 signal circuit. With the sensor disconnected, the signal circuit should be near 0 volt.
-
After replacing the PCM, a new minimum throttle position and idle speed must be established.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views | ||||
Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | ||
2 | Is a DTC P0641 also set? | -- | Go to DTC P0641 | Go to Step 3 |
3 |
Is the APP sensor 1 parameter more than the specified value? | 4.88 V | Go to Step 5 | Go to Step 4 |
Did the DTC fail this ignition? | -- | Go to Step 5 | Go to Intermittent Conditions | |
5 |
Is the voltage more than the specified value? | 0 V | Go to Step 7 | Go to Step 6 |
6 |
Does the test lamp illuminate? | -- | Go to Step 10 | Go to Step 8 |
7 | Test the signal circuit of the APP sensor 1 for short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 11 |
8 | Test the low reference circuit of the APP sensor 1 for an open or high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 9 |
9 | Test for an intermittent and for a poor connection at the powertrain control module (PCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 11 |
10 | Replace the APP sensor 1. Refer to Accelerator Pedal Position Sensor Replacement . Did you complete the replacement? | -- | Go to Step 12 | -- |
Did you complete the replacement? | -- | Go to Step 12 | -- | |
12 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 13 |
13 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |
