| Table 1: | APP Sensor Position Table |
Circuit Description
The accelerator pedal position (APP) sensor is mounted on the accelerator pedal control assembly. The sensor is made up of 3 individual sensors within 1 housing. Three separate signal, low reference, and 5-volt reference circuits are used to interface the APP sensor with the engine control module (ECM). Each sensor has a unique functionality to determine the pedal position as shown in the table below. The ECM uses the APP sensor to determine the amount of acceleration or deceleration desired by the person driving the vehicle via the fuel injector control. If the ECM determines an out of range condition between the APP sensor 1 and the APP sensor 2, DTC P2138 sets.
APP Sensor | Actual Pedal Position | % Depressed as Observed on a Scan Tool | Voltage as Observed on a Scan Tool |
|---|---|---|---|
1 | Pedal at rest | 0 | .52 - .80 |
1 | Pedal at full travel | 100 | 2.12 - 2.78 |
2 | Pedal at rest | 0 | 4.25 - 4.53 |
2 | Pedal at full travel | 100 | 2.24 - 2.93 |
3 | Pedal at rest | 0 | 3.95 - 4.13 |
3 | Pedal at full travel | 100 | 2.69 - 3.16 |
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P2138 Accelerator Pedal Position (APP) Sensor 1-2 Correlation
Conditions for Running the DTC
| • | DTCs P0642, P0643, P0652, P0653, P2122, P2123, P2132, P2133 are not set. |
| • | The ignition switch is in the Crank or Run position. |
| • | The ignition voltage is between 7-16 volts. |
| • | DTC P2138 runs continuously once the above conditions are met. |
Conditions for Setting the DTC
| • | The APP sensor 1 and the APP sensor 2 are more than 10 percent out of range of each other. |
| • | The above condition is present for less than 1 second. |
Action Taken When the DTC Sets
| • | The control module stores the DTC information into memory when the diagnostic runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records. |
| • | If one or more APP sensor DTCs are set for a single APP sensor, the following occurs: |
| - | The control module will not command Reduced Engine Power mode. |
| - | The control module will use the remaining two APP sensors to calculate throttle response. |
| • | If certain multiple APP sensor DTCs are set for more than one APP sensor, the following occurs: |
| - | The control module commands Reduced Engine Power mode. |
| - | The APP indicated angle is limited to a predetermined value to limit the amount of throttle control. |
| - | The message center displays Reduced Engine Power. |
| • | If all three APP sensors are out of range, the following occurs: |
| - | The control module commands Reduced Engine Power mode. |
| - | The APP indicated angle is limited to 0 percent. The control module only allows the engine to idle. |
| - | The message center displays Reduced Engine Power. |
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: 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 DTC fail this ignition? | -- | Go to Step 4 | Go to Step 3 |
3 |
Did this DTC fail this ignition during the above test ? | -- | Go to Step 4 | Go to Intermittent Conditions |
4 |
Does the test lamp illuminate? | -- | Go to Step 5 | Go to Step 14 |
5 | Connect a test lamp between the APP sensor 2, 5-volt reference circuit and the APP sensor 2 low reference circuit. Does the test lamp illuminate? | -- | Go to Step 6 | Go to Step 15 |
6 |
Is the APP sensor 1 voltage less than the specified value? | 1 V | Go to Step 13 | Go to Step 7 |
7 | Is the APP sensor 2 voltage more than the specified value? | 4 V | Go to Step 8 | Go to Step 9 |
8 | Test the APP sensor 1 signal circuit for a short to the APP sensor 3 signal circuit with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 10 |
9 | Test the APP sensor 1 signal circuit for a short to the APP sensor 2 signal circuit with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 10 |
10 |
Does the test lamp illuminate? | -- | Go to Step 11 | Go to Step 16 |
11 | Connect the test lamp between the APP sensor 1, 5-volt reference circuit and the APP sensor 1 low reference circuit. Does the test lamp illuminate? | -- | Go to Step 12 | Go to Step 17 |
12 |
Does the scan tool indicate voltage at the specified value? | 5 V | Go to Step 18 | Go to Step 13 |
13 |
Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 20 |
14 |
Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 20 |
15 |
Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 20 |
16 |
Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 20 |
17 |
Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 20 |
18 | Inspect for poor connections at the harness connector of the APP sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 20 |
19 | Replace the APP sensor assembly. Refer to Accelerator Pedal Position Sensor Replacement . Did you complete the replacement? | -- | Go to Step 22 | -- |
20 | Inspect for poor connections at the harness connector of the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 21 |
21 | Replace the ECM. Refer to Engine Control Module 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 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |
