I have diagnostic trouble code P1125 come up what does it mean?
RESPONSE
Code P1125 – Accelerator Pedal Position Sensor Fault
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.
The Powertrain Control Module (PCM) detects that the difference between Accelerator Pedal Position (APP) sensor 1 and APP sensor 2 is more than the predicted value.
Code P1125 Possible causes
– Faulty Accelerator Pedal Position Sensor
– Accelerator Pedal Position Sensor harness is open or shorted
– Accelerator Pedal Position Sensor circuit poor electrical connection
Code P1125 Diagnostic Chart
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, Code P1125 sets.
Conditions for Running the Diagnostic Trouble COde
| • | 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 | Go to Diagnostic System Check – Engine Controls | ||||||
| 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 Diagnostic Trouble Code (DTC) List | 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 ? | 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? | — | Go to Diagnostic Trouble Code (DTC) List | System OK | ||||||
I have a 6.0 ls engine I put in a 69 c10. Was cranking fine. But stopped cranking. Got a code of p1125. Purchased a new complete accelerator pedal position sensor. Installed it an cleared the code out. But engine still want start. Just turns over. Any help with this will be greatly appreciated.
Alvin, We have created a Step by Step diagnostic chart for such an issue: https://www.freeautomechanic.com/nostart.html
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