| 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 in order 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 high voltage with the APP sensor 2 circuit, DTC P2127 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 P2127 Accelerator Pedal Position (APP) Sensor 2 Circuit Low Voltage
Conditions for Running the DTC
| • | DTCs P0652 or P0653 are not set. |
| • | The ignition switch is in the Crank or Run position. |
| • | The ignition voltage is between 7-16 volts. |
| • | DTC P2127 runs continuously. |
Conditions for Setting the DTC
| • | The APP sensor 2 voltage is less than 0.25 volts. |
| • | 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 - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
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 8 | Go to Intermittent Conditions |
4 |
Does the DMM indicate voltage within the specified range? | 4.8-5.2 V | Go to Step 5 | Go to Step 6 |
5 | Test for voltage at the APP sensor 2 signal circuit with a DMM. Does the DMM indicate voltage at the specified value? | 5.05 V | Go to Step 9 | Go to Step 7 |
6 |
Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 10 |
7 |
Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 10 |
8 | Repair the intermittent condition, as necessary. Refer to Connector Repairs and Repairing Connector Terminals in Wiring Systems. Did you complete the repair? | -- | Go to Step 13 | -- |
9 | 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 13 | Go to Step 11 |
10 | 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 13 | Go to Step 12 |
11 | Replace the APP sensor assembly. Refer to Accelerator Pedal Position Sensor Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- |
12 | Replace the ECM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 13 | -- |
13 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 14 |
14 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information | System OK |
