Circuit Description
The accelerator pedal position (APP) sensor 1 is a potentiometer type sensor with the following three circuits:
| • | A 5-volt reference circuit |
| • | A low reference circuit |
| • | A signal circuit |
The control module provides the APP sensor a 5-volt reference circuit and a low reference circuit. The APP sensor then provides the control module a signal voltage proportional to pedal movement. The APP sensor 1 signal voltage is low at rest and increases as the pedal is depressed. When the control module detects that the APP sensor 1 signal or the APP sensor 5-volt reference voltage is outside the predetermined range, DTC P2120 sets.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P2120 Accelerator Pedal Position (APP) Sensor 1 Circuit
Conditions for Running the DTC
| • | DTC P2107 is not set. |
| • | The ignition is ON. |
| • | The ignition voltage is more than 5.23 volts. |
Conditions for Setting the DTC
| • | The APP sensor 1 voltage is less than 0.235 volt or more than 4.487 volts. |
| OR |
| • | The APP sensor 1 5-volt reference voltage is less than 4.54 volts or more than 5.21 volts. |
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 DTC
| • | 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 non-emission related diagnostic. |
| • | Clear the DTC with a scan tool. |
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Powertrain Control Module Connector End Views and Engine Controls Connector End Views | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
2 |
Is the voltage within the specified range? | 0.24-2 V | Go to Step 4 | Go to Step 3 |
3 |
Is the voltage within the specified range? | 4.6-5.2 V | Go to Step 6 | Go to Step 9 |
4 | Is DTC P2138 also set? | -- | Go to Step 5 | |
5 |
Did the DTC fail this ignition? | -- | Go to Step 6 | Go to Intermittent Conditions |
6 |
Is the voltage at the specified value? | 0 V | Go to Step 7 | Go to Step 11 |
7 |
Is the voltage within the specified value? | 4.6-5.2 V | Go to Step 13 | Go to Step 8 |
8 |
Is the voltage within the specified range? | 4.6-5.2 V | Go to Step 10 | Go to Step 9 |
9 | Does the DMM indicate voltage less than the specified value on the APP sensor 1 5-volt reference circuit? | 5 V | Go to Step 14 | Go to Step 16 |
10 | Test the APP sensor 1 signal circuit for an open or for high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 12 |
11 | Test the APP sensor 1 signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 19 |
12 | Test the APP sensor 1 signal circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 19 |
13 | Test the APP sensor 1 low reference circuit for an open or for high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 17 |
14 | Test the APP sensor 1 5-volt reference circuit for an open or for high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 15 |
15 | Test the APP sensor 1 5-volt reference circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 19 |
16 | Test the APP sensor 1 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 22 | Go to Step 19 |
17 | Is DTC U0107 also set? | -- | Go to Step 18 | |
18 | 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 22 | Go to Step 20 |
19 | Test for an intermittent and for a poor connection at the throttle body harness connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 21 |
20 | Replace the accelerator pedal assembly. Refer to Accelerator Pedal Replacement . Did you complete the replacement? | -- | Go to Step 22 | -- |
21 | Replace the throttle body. Refer to Throttle Body Assembly Replacement . Did you complete the replacement? | -- | Go to Step 22 | -- |
22 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 23 |
23 |
Important: Be aware that repairing one individual condition may correct more than one DTC. Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |
