Circuit Description
The accelerator pedal position (APP) sensor 1 and APP sensor 2 are potentiometer type sensors, each with the following circuits:
| • | A 5-volt reference circuit |
| • | A low reference circuit |
| • | A signal circuit |
The control module provides the APP sensors a 5-volt reference circuit and a low reference circuit. The APP sensors then provide the control module signal voltages proportional to pedal movement. The APP sensor 1 and the APP sensor 2 signal voltages are both low at rest and increase as the pedal is depressed. When the control module detects that the APP sensor 1 and the APP sensor 2 signal circuits are out of correlation, DTC P2138 sets.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P2138 Accelerator Pedal Position (APP) Sensor 1-2 Correlation
Conditions for Running the DTC
| • | DTC P2107 is not set. |
| • | The ignition is in the crank or run position. |
| • | The Ignition 1 Signal parameter is more than 5.23 volts. |
| • | The communication between the TAC module and the powertrain control module (PCM) must be valid. |
Conditions for Setting the DTC
The accelerator pedal position indicated by APP sensor 1 disagrees with the accelerator pedal position indicated by APP sensor 2 by more than 0.269 volts for longer than 135 milliseconds. This test occurs continuously.
OR
The PCM learned minimum accelerator pedal position of APP sensor 1 disagrees with the learned minimum accelerator pedal position of APP sensor 2. This test occurs once per ignition cycle at power-up.
OR
The PCM detects that the APP sensor 1 signal circuit is shorted to the APP sensor 2 signal circuit, to voltage, or to ground for longer than 100 milliseconds. This test occurs continuously.
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 | Observe the DTC Information with a scan tool. Is DTC P0641 or P0651 also set? | -- | Go to Step 3 | |||||||
3 |
Is the resistance more than the specified value for any circuit? | 5 ohms | Go to Step 7 | Go to Step 4 | ||||||
4 | Test the signal circuit of the APP sensor 1 for a short to the signal circuit of the APP sensor 2. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 5 | ||||||
5 | Test for an intermittent and for a poor connection at the APP pedal assembly. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 6 | ||||||
6 | 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 9 | Go to Step 8 | ||||||
7 | Repair the high resistance in the circuit that measured above the specified value. Refer to Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 9 | -- | ||||||
8 | Replace the APP sensor. Refer to Accelerator Pedal Position Sensor Replacement . Did you complete the replacement? | -- | Go to Step 9 | -- | ||||||
9 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 10 | ||||||
10 |
Important: Be aware that repairing 1 individual condition may correct more than 1 DTC. Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |||||||
