For 1990-2009 cars
Handling ESD Sensitive Parts Notice
Engine Controls Components
Cell 20: Accelerator Pedal Position (APP) Sensor
OBD II Symbol Description Notice

### Circuit Description

The accelerator pedal position (APP) sensors are two sensors that are housed inside one assembly.

The ECM supplies the 5 volt reference and the ground circuit for both of the sensors. The APP 1 sensor sends a signal to the ECM of the drivers demand. The ECM then calculates the proper spark and PWM fueling.

The APP 1 sensor is the main control of the system. The APP 2 sensor is used for comparison of the APP 1 sensor. The ECM constantly monitors these two sensors and if the sensors are not within a calibrated value a DTC will set.

### Conditions for Running the DTC

The battery voltage is more than 7 volts.

### Conditions for Setting the DTC

This DTC will set if the voltage difference between accelerator pedal position (APP) sensor 1 and APP sensor 2 is not correct when leaving idle.

### Action Taken When the DTC Sets

The ECM illuminates the malfunction indicator lamp (MIL) and records the operating conditions in the Freeze Frame on the first drive trip that the diagnostic runs and fails. The vehicle will default to the limp home mode.

### Conditions for Clearing the MIL/DTC

• | The ECM turns off the MIL after 3 consecutive drive trips that the diagnostic runs and does not fail.

• | A History DTC clears after 40 consecutive warm up cycles in which no failures are reported by this diagnostic or any other emission related diagnostic.

• | The ECM battery voltage is interrupted.

• | The scan tool clears the MIL/DTC.

### Diagnostic Aids

With the ignition ON and the engine OFF view the APP sensor 1 and the APP sensor 2 with a scan tool. Slowly depress the accelerator pedal, if one sensor value changes and the other does not, inspect the sensor circuits for high resistance or shorts. If the circuits are OK, replace the APP sensor.

Notice: Using the J 35616-A Connector Test Adapter Kit will prevent damage to the harness connector terminals.

Use the J 35616 Connector Test Adapter Kit for any test that requires probing the ECM harness connector or a component harness connector.

Check for the following conditions:

• | Poor connections at the ECM or at the component--Inspect the harness connectors for the following conditions:

- | Backed out terminals

- | Improper mating

- | Broken locks

- | Poor terminal to wire connection

- | Refer to Engine Control Module Diagnosis , Checking Terminal Contact for the proper procedure.

• | Damaged harness--Inspect the wiring harness for damage. If the harness appears to be OK, observe the scan tool while moving the related connectors and the wiring harnesses. A change in the display may help in order to locate the fault. If the sensor signal is only affected when the harness is moved at a component, and there is no problem with the harness or the connections, the component may be damaged.

| Refer to Symptoms for the Intermittents.

• | Inspect the APP sensor mounting bolts and actuator arm. The bolts should be tight. If the APP sensor is loose, a false reading could be sent to the ECM.

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 | Are any other APP DTCs set? | -- | Go to applicable DTC | Go to Step 3
3 |

1. Turn the ignition OFF.
2. Disconnect the APP sensor electrical connector.
3. Disconnect the ECM.
4. Use a J 39200 digital multimeter (DMM) to measure the resistance (continuity) of the following circuits:

• | The ground circuit

• | The signal circuit

• | The 5 V reference circuit

Did any of the circuits measure greater than the specified value?

5 Ohms

Go to Step 7

Go to Step 4

4 |

1. Use a J 39200 digital multimeter (DMM) to measure the resistance to GROUND of the following circuits:

• | The ground circuit

• | The signal circuit

• | The 5 V reference circuit

2. Use a J 39200 digital multimeter (DMM) to measure the resistance BETWEEN all of the following circuits:

• | The ground circuit

• | The signal circuit

• | The 5 V reference circuit

Did ALL of the circuits indicate infinite resistance or open loop?

OL

Go to Step 5

Go to Step 6

5 | Replace the APP sensor. Refer to Accelerator Pedal Position Sensor Replacement . Is the action complete? | -- | Go to Step 8 | --
6 | Repair the short to ground in the circuit or the APP circuits that are shorted together. Is the action complete? | -- | Go to Step 8 | --
7 | Repair the high resistance in the circuit. Is the action complete? | -- | Go to Step 8 | --
8 |

1. Using the scan tool, clear the DTCs. Start the engine.
2. Operate the vehicle within the Conditions for Setting this DTC.

Does this DTC reset?

--

Go to Step 2

Go to Step 9

9 | Does the scan tool display any additional, undiagnosed DTCs? | -- | Go to the applicable DTC table | System OK