| Table 1: | APP Sensor Position Table |
Circuit Description
The accelerator pedal position (APP) sensor is mounted on the accelerator pedal assembly. The sensor is actually 3 individual APP sensors within 1 housing. Three separate signal, low-reference and 5-volt reference circuits connect the APP sensor assembly to the throttle actuator control (TAC) module. Each sensor has a unique functionality.
TP sensor 1 and APP sensor 1 share a 5-volt reference circuit that are connected within the TAC module. TP sensor 2 and APP sensor 2 share a 5-volt reference circuit that are connected within the TAC module. If only 1 APP sensor DTC is set, the redundant APP systems allow the TAC system to continue operating normally. One APP sensor DTC will not cause the Reduced Engine Power message to be displayed. Two APP sensor DTCs for the same sensor also will not cause the Reduced Engine Power message to be displayed. If an out of range condition is detected with this APP sensor, this DTC will be set.
The table below shows the percentage and voltage readings of the scan tool based on the position of the APP.
APP Sensor | Actual Pedal Position | % Depressed as Observed on the Scan Tool | Voltage as Observed on the Scan Tool |
|---|---|---|---|
1 | Pedal at rest | 0 | Below 1.0 |
1 | Pedal at full travel | 100 | Above 2.0 |
2 | Pedal at rest | 0 | Above 4.0 |
2 | Pedal at full travel | 100 | Below 2.9 |
3 | Pedal at rest | 0 | Above 3.8 |
3 | Pedal at full travel | 100 | Below 3.1 |
Conditions for Running the DTC
| • | DTCs P0606, P1517, or P1518 are not set. |
| • | The ignition switch is in the crank or run position. |
| • | The ignition voltage is greater than 5.23 volts. |
Conditions for Setting the DTC
| • | APP sensor 3 disagrees with APP sensor 1 by more than 13 percent and APP sensor 3 disagrees with APP sensor 2 by more than 13 percent. |
| • | All of the above conditions are 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. |
Diagnostic Aids
| • | Inspect the TAC module connectors for signs of water intrusion. When this condition occurs, multiple DTCs could be set without circuit or component conditions found during diagnostic testing. |
| • | When the TAC module detects throttle movement with a DTC P1285 set, a DTC P1286 also sets. |
| • | 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. Be aware of 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 on 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 1 and sensor 2 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. When the pedal is at rest, the APP angle for all 3 sensors should be 0 percent. When the pedal is fully depressed, all APP angles should be 100 percent.
-
The APP sensor 3 has a dedicated 5-volt reference circuit. Monitoring the APP sensor 1 voltage aids in diagnosing the APP sensor 3, 5-volt reference circuit. If the scan tool displays 5 volts, then the circuits are OK.
-
When the TAC module detects a condition within the TAC system, more than 1 TAC system-related DTC may set. This condition is due to the many redundant tests that continuously run on this system. Locating and repairing 1 individual condition may correct more than 1 DTC. Disconnecting components during testing may set additional DTCs. Be aware of this condition if you review the stored information in Capture Info.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |
Is DTC P1518 also set? | -- | Go to DTC P1518 | Go to Step 3 | |
3 |
Important: DO NOT depress the accelerator pedal.
Did any other TAC module or APP sensor DTCs set except P1125? | -- | Go to Step 4 | |
4 | Use a scan tool in order to observe the APP sensor Agree/Disagree parameters. Does the scan tool indicate Disagree for any of the APP sensor Agree/Disagree parameters? | -- | Go to Step 6 | Go to Step 5 |
Does the scan tool indicate APP sensor 3 angle within 13 percent of the APP sensor 1 angle? Is the APP sensor 3 angle within 13 percent of the APP sensor 2 angle during the above test? | -- | Go to Diagnostic Aids | Go to Step 6 | |
Does the DMM indicate voltage within the specified values | 3.94-6.06 V | Go to Step 7 | Go to Step 14 | |
7 | Use a DMM in order to test the APP sensor 3 signal circuit for voltage. Does the DMM indicate voltage within the specified values | 3.94-6.06 V | Go to Step 8 | Go to Step 16 |
8 | With a DMM connected between the APP sensor 3 low reference circuit and the APP sensor 1 low reference circuit, measure the resistance. Does the DMM indicate resistance within the specified values? | 0-5 ohms | Go to Step 9 | Go to Step 19 |
9 |
Did you find and correct the condition? | -- | Go to Step 24 | Go to Step 10 |
10 | Use a DMM in order to test for a short between the APP sensor 3, 5-volt reference circuit and all other APP circuits at the APP sensor harness connector. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 24 | Go to Step 11 |
11 | Use a DMM in order to test the APP sensor 3 signal circuit for resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 24 | Go to Step 12 |
12 | Use a DMM in order to test for a short between the APP sensor 3 signal circuit and all other APP circuits at the APP sensor harness connector. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 24 | Go to Step 13 |
13 | Use a DMM in order to test the APP sensor 3 low reference circuit for resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 24 | Go to Step 20 |
14 |
Did you find and correct the condition? | -- | Go to Step 24 | Go to Step 15 |
15 | Use a DMM in order to test the APP sensor 3, 5-volt reference circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 24 | Go to Step 21 |
16 |
Did you find and correct the condition? | -- | Go to Step 24 | Go to Step 17 |
17 | Use a DMM in order to test the APP sensor 3 signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 24 | Go to Step 18 |
18 | Use a DMM in order to test for a short between the APP sensor 3 signal circuit and all other APP circuits at the APP sensor harness connector. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 24 | Go to Step 19 |
19 |
Did you find and correct the condition? | -- | Go to Step 24 | Go to Step 21 |
20 | Inspect for poor connections at the harness connector of the APP sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 24 | Go to Step 22 |
21 | Inspect for poor connections at the harness connectors of the TAC module. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 24 | Go to Step 23 |
22 | Replace the APP sensor assembly. Refer to Accelerator Pedal Position Sensor Replacement . Did you complete the replacement? | -- | Go to Step 24 | -- |
23 | Replace the TAC module. Refer to Electronic Throttle Actuator Control Module Replacement . Did you complete the replacement? | -- | Go to Step 24 | -- |
24 |
Does the DTC run and pass? | -- | Go to Step 25 | Go to Step 2 |
With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | ||
