Circuit Description
The accelerator pedal position (APP) sensor 1 and the 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 with 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 signal voltage is low at rest and increases as the pedal is depressed. The APP sensor 2 signal voltage is low at rest and increases 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 with each other, DTC P1125 sets.
Conditions for Running the DTC
| • | DTC P1518, P2108 or U0107 is not set. |
| • | The ignition is in the Crank or Run position. |
| • | The ignition voltage is more than 5.23 volts. |
| • | The communication between the throttle actuator control (TAC) module and the powertrain control module (PCM) must be valid. |
Conditions for Setting the DTC
The PCM detects that the difference between APP sensor 1 and APP sensor 2 is more than the predicted value.
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 MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL) after 3 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. |
Step | Action | Values | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views or Powertrain Control Module Connector End Views | ||||||||||
1 | Did you perform the Diagnostic System Check - Engine Controls? | -- | Go to Step 2 | |||||||
2 | Record the throttle actuator control (TAC) module calibration with a scan tool. Does the TAC module calibration match the part number of the TAC module? | -- | Go to Step 3 | Go to Step 11 | ||||||
3 | Observe the DTC Information with a scan tool. Is DTC P2120 or P2125 also set? | -- | Go to Step 4 | |||||||
4 |
Does the scan tool indicate that the APP sensors 1 and 2 parameters disagree? | -- | Go to Step 5 | Go to Intermittent Conditions | ||||||
5 |
Is the resistance more than the specified value for any circuit? | 5 ohms | Go to Step 9 | Go to Step 6 | ||||||
6 | 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 in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 7 | ||||||
7 | Test for an intermittent and for a poor connection at the TAC module. 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 12 | Go to Step 8 | ||||||
8 | 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 12 | Go to Step 10 | ||||||
9 | Repair the high resistance in the circuit that measured above the specified value. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | -- | ||||||
10 | Replace the APP sensor. Refer to Accelerator Pedal Position Sensor Replacement . Did you complete the replacement? | -- | Go to Step 12 | -- | ||||||
11 | Replace the TAC module. Refer to Electronic Throttle Actuator Control Module Replacement . Did you complete the replacement? | -- | Go to Step 12 | -- | ||||||
12 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 13 | ||||||
13 |
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 | |||||||
