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 engine control module (ECM) 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 2.5 volts when fully depressed. The APP sensor 2 signal voltage decreases as the pedal is depressed, from approximately 4 volts at rest to less than 1 volt with the accelerator pedal fully depressed. If the ECM detects that the APP sensor 2 signal voltage is too high, this DTC sets.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P2128 Accelerator Pedal Position (APP) Sensor 2 Circuit High Voltage
Conditions for Running the DTC
| • | The ignition is ON. |
| • | The ignition voltage is more than 5.23 volts. |
| • | DTCs P0601, P0602, P0603, P0604, P0606, P0607, P0641, P0651 are not set. |
| • | DTC P2128 runs continuously when the above conditions are met. |
Conditions for Setting the DTC
The ECM detects that the APP sensor 2 voltage is more than 4.2 volts for more than one 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 and/or the Failure Records. |
| • | The control module commands the TAC system to operate in the Reduced Engine Power mode. |
| • | A message center or an indicator displays Reduced Engine Power. |
| • | Under certain conditions the control module commands the engine OFF. |
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. |
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
2 |
Is the APP sensor 2 voltage parameter more than the specified value? | 4.2 V | Go to Step 4 | Go to Step 3 |
3 |
Did the DTC fail this ignition? | -- | Go to Step 4 | Go to Testing for Intermittent Conditions and Poor Connections |
4 |
Does the DMM indicate voltage within the specified range? | 4.8-5.2 V | Go to Step 5 | Go to Step 10 |
5 | With a test lamp connected to ground, probe the APP sensor 2 signal circuit. Does the test lamp illuminate? | -- | Go to Step 8 | Go to Step 6 |
6 | Observe the APP Sensor 2 parameter, with the test lamp still connected to the APP sensor 2 signal circuit. Does the scan tool indicate voltage at the specified value? | 0 V | Go to Step 9 | Go to Step 7 |
7 | Test the APP sensor 2 signal circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 13 |
8 | Test the APP sensor 2 signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 11 |
9 | Test the APP sensor 2 low reference circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 12 |
10 | Test the APP sensor 2 5-volt reference circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 11 |
11 | Test for shorted terminals and for a poor connection at the engine control module (ECM) harness connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | - | Go to Step 16 | Go to Step 15 |
12 | Test for an intermittent and for a poor connection at the accelerator pedal harness connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 14 |
13 | Test for an intermittent and for a poor connection at the ECM harness connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 16 | Go to Step 15 | |
14 | Replace the accelerator pedal assembly. Refer to Accelerator Pedal Position Sensor Replacement . Did you complete the replacement? | -- | Go to Step 16 | -- |
15 | Replace the ECM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 16 | -- |
16 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 17 |
17 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |
