For 1990-2009 cars

### Circuit Description

The accelerator pedal position (APP) sensor 1 and sensor 2 are located within the accelerator pedal assembly. Each sensor has the following circuits:

• | A 5-volt reference

• | A low reference

• | A signal

This provides the powertrain control module (PCM) with a signal voltage proportional to accelerator pedal movement. The APP sensor 1 signal voltage at rest position is near the low reference and increases as the pedal is actuated. The APP sensor 2 signal voltage at rest position is near the 5-volt reference and decreases as the pedal is actuated. If the PCM detects the APP sensor 1 signal voltage is not within the predicted range, DTC P2122 sets.

### DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P2122 Accelerator Pedal Position (APP) Sensor 1 Circuit Low Voltage

### Conditions for Running the DTC

• | The ignition is ON.

• | The ignition voltage is more than 5.23 volts.

• | DTC P0641 is not set.

• | DTC P2122 runs continuously when the above conditions are met.

### Conditions for Setting the DTC

The PCM detects that the APP sensor 1 voltage is less than 0.13 volts for more than 0.4 seconds.

### 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 Controls Connector End Views or Powertrain Control Module Connector End Views
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 |

1. Turn ON the ignition, with the engine OFF.
2. Observe the accelerator pedal position (APP) sensor 1 voltage with the accelerator pedal in the rest position, with a scan tool.

Is the APP sensor 1 voltage parameter less than the specified value?

0.13 V

Go to Step 4

Go to Step 3

3 |

1. Observe the Freeze Frame/Failure records for this DTC.
2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

--

Go to Step 4

Go to Intermittent Conditions

4 |

1. Turn OFF the ignition.
2. Disconnect the accelerator pedal connector.
3. Turn ON the ignition, with the engine OFF.
4. Measure the voltage from the 5-volt reference circuit of APP sensor 1 to a good ground with a DMM. Refer to Circuit Testing .

Does the DMM indicate voltage within the specified range?

4.8-5.2 V

Go to Step 5

Go to Step 6

5 |

1. Connect a fused jumper wire between the 5-volt reference circuit and the signal circuit of APP sensor 1.
2. Observe the APP sensor 1 voltage parameter with a scan tool.

Is the APP sensor 1 voltage parameter within the specified range?

4.8-5.2 V

Go to Step 11

Go to Step 7

6 | Test the APP 5-volt reference circuit for the following conditions:

• | An open

• | A short to ground

• | High resistance

Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 12

Go to Step 8

7 | Test the APP sensor 1 signal circuit for the following conditions:

• | An open

• | A short to ground

• | High resistance

Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 12

Go to Step 8

8 | Test for an intermittent and for a poor connection at the APP sensor. 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 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 10
10 | Replace the PCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 12 | --
11 | Replace the accelerator pedal assembly. Refer to Accelerator Pedal Position Sensor Replacement . Did you complete the replacement? | -- | Go to Step 12 | --
12 |

1. Clear the DTCs with a scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

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? | -- | Go to Diagnostic Trouble Code (DTC) List - Vehicle | System OK