Circuit Description
The accelerator pedal assembly contains 2 accelerator pedal position (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 engine control module (ECM) 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 1 volt at rest to above 4 volts when fully depressed. The APP sensor 2 signal voltage increases as the pedal is depressed, from approximately 0.5 volts at rest to more than 2 volts with the accelerator pedal fully depressed.
If the ECM detects that the difference between APP sensor 1 and 2 signal voltage is more than a predetermined value, this DTC 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
| • | The battery voltage is more than 7 volts. |
| • | The ignition is ON or the engine is operating. |
| • | DTC P2138 run continuously once the above conditions are met for more than 1 second. |
Conditions for Setting the DTC
This DTC set when one of the following conditions occur:
| • | The ECM detects that the voltage difference between APP sensor 1 and 2 is more than 0.21 volts. |
| • | The ECM detects that the voltage difference between APP sensor 1 and 2 is more than 0.27 volts with a partially pressed pedal. |
| • | The ECM detects that the voltage difference between APP sensor 1 and 2 is more than 1.07 volts with a fully pressed pedal. |
| • | The ECM detects that the APP sensor 1 voltage is more then 1.17 when leaving the idle range and the voltage difference between APP sensor 1 and 2 is more than 0.04. |
| • | The above conditions are met for less than 1 second. |
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/Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL) after 4 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. |
Diagnostic Aids
| • | Use the J 35616 Connector Test Adapter Kit for any test that requires probing the ECM harness connector or a component harness connector. |
| • | The lower connector of the ECM is connector C1 and the upper connector of the ECM is connector C2. Refer to Engine Controls Component Views . |
| • | If DTCs P0700, P2122, P2128, and P2138 are set together in various combinations, inspect the APP sensor 1 and 2 signal circuits for being shorted together. |
| • | For an intermittent condition, refer to Intermittent Conditions . |
Step | Action | Values | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views | ||||||||||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |||||||||
2 |
Does the scan tool display Agree? | -- | Go to Step 4 | Go to Step 3 | ||||||||
3 | Observe the DTC information with a scan tool. Is DTC P0101, P0122, P0123, P0222, P0223, P2122, P2123, P2127, P2128 also set? | -- | Go to Step 5 | |||||||||
4 |
Did the DTC fail this ignition? | -- | Go to Step 5 | Go to Diagnostic Aids | ||||||||
5 |
Important: Use the J 35616-200 Test Lamp Kit for this test. If the J 35616-200 is not available, use a test lamp that measures more than 20 ohms. Is the voltage within the specified range? | 4.8-5.1 V | Go to Step 6 | Go to Step 11 | ||||||||
6 |
Important: Use the J 35616-200 Test Lamp Kit for this test. If the J 35616-200 is not available, use a test lamp that measures more than 20 ohms. Is the voltage within the specified range? | 4.8-5.1 V | Go to Step 7 | Go to Step 11 | ||||||||
7 |
Is the voltage more than the specified value? | 4.8 V | Go to Step 8 | Go to Step 12 | ||||||||
8 |
Is the voltage more than the specified value? | 4.8 V | Go to Step 9 | Go to Step 12 | ||||||||
9 |
Notice: Do NOT use a test lamp to test the continuity of the circuit. Damage to the control module may occur due to excessive current draw. Is the resistance less than the specified value? | 10 ohms | Go to Step 10 | Go to Step 13 | ||||||||
10 |
Notice: Do NOT use a test lamp to test the continuity of the circuit. Damage to the control module may occur due to excessive current draw. Measure the resistance from the low reference circuit of the APP sensor 2 to a good ground with a DMM. Is the resistance less than the specified value? | 10 ohms | Go to Step 14 | Go to Step 13 | ||||||||
11 |
Important: The engine control module (ECM) for this engine is not equipped with 5-volt reference DTCs. The 5-volt reference circuits are internally and externally connected at the controller. Other sensors that share the 5-volt reference circuit may also have DTCs set. Disconnecting a sensor on the shared 5-volt reference circuit may isolate a shorted sensor. Review the electrical schematic and diagnose the shared circuits and sensors. Test the 5-volt reference circuit of the APP sensor 1 or 2 for the following:
Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 19 | Go to Step 16 | ||||||||
12 | Test the signal circuit of the APP sensor 1 or 2 for the following:
Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 19 | Go to Step 16 | ||||||||
13 | Test the low reference circuit of the APP sensor 1 or 2 for a high resistance or for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 19 | Go to Step 16 | ||||||||
14 | Test the signal circuit of APP sensor 1 for a short to the signal circuit of APP sensor 2. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 19 | Go to Step 15 | ||||||||
15 | 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 in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 19 | Go to Step 17 | ||||||||
16 | Test for an intermittent and for a poor connection at the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 19 | Go to Step 18 | ||||||||
17 | Replace the APP sensor. Refer to Accelerator Pedal Position Sensor Replacement . Did you compete the replacement? | -- | Go to Step 19 | -- | ||||||||
18 | Replace the engine control module (ECM). Refer to Engine Control Module Replacement . Did you complete the replacement? | -- | Go to Step 19 | -- | ||||||||
19 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 20 | ||||||||
20 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |||||||||
