Circuit Description
The DTC P2120 Accelerator Pedal Position (APP) Sensor 1 Circuit diagnostic monitors the APP sensor 1 signal circuit. The accelerator pedal assembly contains 2 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 0.75 volts at rest to about 4 volts when fully depressed. The APP sensor 2 signal voltage increases as the pedal is depressed, from approximately 1.6 volts at rest to more than 4.8 volts with the accelerator pedal fully depressed.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P2120 Accelerator Pedal Position (APP) Sensor 1 Circuit
Conditions for Running the DTC
| • | The ignition is ON or the engine is running. |
| • | DTC P2120 runs continuously once the above condition has been met. |
Conditions for Setting the DTC
The APP sensor 1 voltage is less than 0.2 volts for less than 1 second.
OR
The APP sensor 1 voltage is more than 4.8 volts for less than 1 second.
Action Taken When the DTC Sets
| • | The PCM illuminates the malfunction indicator lamp (MIL). |
| • | The PCM stores the conditions that were present when the DTC set as Freeze Frame data. |
| • | The engine will operate in the reduced power mode and the APP sensor will default to idle. |
Conditions for Clearing the MIL/DTC
| • | The PCM turns OFF the MIL on the third consecutive trip in which the diagnostic runs without a fault. |
| • | The PCM clears a History DTC after 40 consecutive warm-up cycles without a fault. |
| • | You use the scan tool Clear DTC Information function. |
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 the signal and the 5-volt reference circuits.
-
This step tests for an open in the APP sensor 1 low reference circuit. The control module will receive a high voltage signal if the low reference circuit is open.
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 the APP sensor 1 parameter less than the specified value? | 0.2 V | Go to Step 5 | Go to Step 3 | ||||
3 | Is the APP sensor 1 parameter more than the specified value? | 4.8 V | Go to Step 9 | Go to Step 4 | ||||
4 |
Did the DTC fail this ignition? | -- | Go to Step 5 | Go to Intermittent Conditions | ||||
Is the APP sensor 1 voltage within the specified range? | 4.8-5.2 V | Go to Step 12 | Go to Step 6 | |||||
6 | Connect a DMM between the 5-volt reference circuit of the APP sensor 1 and a good ground. Is the measured voltage within the specified range? | 4.8-5.2 V | Go to Step 7 | Go to Step 8 | ||||
7 | Test the APP sensor 1 signal circuit for the following conditions:
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 5-volt reference circuit of the APP sensor 1 for an open circuit. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 13 | ||||
Does the test lamp illuminate? | -- | Go to Step 10 | Go to Step 11 | |||||
10 | Test the input circuit of the APP sensor 1 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 15 | ||||
11 | Test for an open in the low reference circuit of the APP sensor 1. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 13 | ||||
12 | Test for an intermittent and for a poor connection at the APP sensor 1. 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 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 16 | Go to Step 15 | ||||
14 | Replace the APP sensor 1. Refer to Accelerator Pedal Position Sensor Replacement . Did you complete the replacement? | -- | Go to Step 16 | -- | ||||
15 | Replace the PCM. 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 | |||||
