Circuit Description
The accelerator pedal position (APP) sensor 1 and 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 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 also low at rest and increases as the pedal is depressed. When the control module detects that the APP sensor 1 signal and the APP sensor 2 signal circuits are out of correlation, this DTC sets.
Conditions for Running the DTC
| • | DTCs P0606, P1518, or P2108 are not set. |
| • | The ignition switch is in the crank or run position. |
| • | The ignition voltage is more than 5.23 volts. |
Conditions for Setting the DTC
| • | APP sensor 1 disagrees with APP sensor 2 by more than 10.5 percent. |
| • | The above condition is present for more 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 commands Reduced Engine Power mode. |
| - | The APP indicated angle is limited to a predetermined value to limit the amount of throttle control. |
| - | 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. |
Diagnostic Aids
| • | Inspect the throttle actuator control (TAC) module connectors for signs of water intrusion. If water intrusion occurs, multiple DTCs may set without any circuit or component conditions found during diagnostic testing. |
| • | When the TAC module detects a condition within the TAC system, more than 1 TAC system related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing 1 individual condition may correct more than 1 DTC. Disconnecting components during testing may set additional DTCs. Remember this if you review the stored information in Capture Info. |
| • | For an intermittent, refer to Intermittent Conditions . |
Test Description
The numbers below refer to the step numbers in the diagnostic table.
-
This step determines if a communication condition exists.
-
This step isolates an internal APP sensor failure. The condition may only occur at a certain accelerator pedal position. Monitoring the APP angles for sensor 2 and sensor 3 is an accurate way of verifying the actual position of the pedal. The APP angles for all 3 sensors should be within a few percent of each other. If the pedal is at rest, the APP angle for all 3 sensors should be 0 percent. If the pedal is fully depressed, all APP angles should be 100 percent.
-
The APP sensor 1 shares a common 5-volt reference circuit with the throttle position (TP) sensor 1. Monitoring the TP sensor 1 voltage aids in diagnosing the APP sensor 5-volt reference and low-reference circuits. If the scan tool displays near 0 volts, the circuits are OK.
-
With the TAC module still connected, this test will help determine a short to the signal circuit either within the TAC module or wiring.
-
This step determines whether the TAC module or a shorted circuit is causing the condition.
-
When the TAC module detects a condition within the TAC system, more than 1 TAC system related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing 1 individual condition may correct more than 1 DTC. Disconnecting components during testing may set additional DTCs. Remember this if you review the stored information in Capture Info.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Powertrain 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 | |
Is DTCs P1518 also set? | -- | Go to DTC P1518 | Go to Step 3 | |
3 |
Important: Do not depress the accelerator pedal.
Did any other throttle actuator control (TAC) module or APP sensor DTC set except P1125? | -- | Go to Step 4 | |
4 | Observe the accelerator pedal position (APP) sensor Agree/Disagree parameters with a scan tool. Does the scan tool indicate Disagree for any of the APP Agree/Disagree parameters? | -- | Go to Step 6 | Go to Step 5 |
Does the scan tool indicate APP sensor 1 angle within 10.5 percent of the APP sensor 2 angle during the above test? | -- | Go to Diagnostic Aids | Go to Step 6 | |
Does the scan tool indicate TP sensor 1 voltage at the specified value? | 0.0 V | Go to Step 7 | Go to Step 11 | |
7 |
Does the scan tool indicate TP sensor 1 voltage at specified value? | 0.0 V | Go to Step 8 | Go to Step 12 |
8 |
Does the scan tool indicate APP sensor 1 voltage near the specified value? | 5.0 V | Go to Step 14 | Go to Step 9 |
Test for a short between the APP sensor 1 signal circuit and all other APP circuits at the APP sensor harness connector with a DMM. Does the DMM indicate a short to another circuit? | -- | Go to Step 10 | Go to Step 13 | |
Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 15 | |
11 |
Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 15 |
12 |
Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 15 |
13 |
Did you find an open or high resistance? | -- | Go to Step 18 | Go to Step 15 |
14 | 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 18 | Go to Step 16 |
15 | Inspect for poor connections at the harness connectors of the TAC module. 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 18 | Go to Step 17 |
16 | Replace the APP sensor assembly. Refer to Accelerator Pedal Position Sensor Replacement . Did you complete the replacement? | -- | Go to Step 18 | -- |
17 | Replace the TAC module. Refer to Electronic Throttle Actuator Control Module Replacement . Did you complete the replacement? | -- | Go to Step 18 | -- |
18 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 19 |
Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | ||
