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. The APP sensor 1 signal is pulled up to the reference voltage as the accelerator pedal is depressed, from below 1 volt at 0 percent pedal travel, with the pedal at rest, to above 2 volts at 100 percent pedal travel, with the pedal fully depressed. The APP sensor 2 signal is pulled down to the low reference from above 4 volts at 0 percent pedal travel to below 2.9 volts at 100 percent pedal travel. The APP sensor 3 signal is pulled down to low reference from above 3.8 volts at 0 percent pedal travel to below 3.1 volts at 100 percent pedal travel. TP sensor 1 and APP sensor 1 share a 5-volt reference circuit that is connected within the TAC module. TP sensor 2 and APP sensor 2 share a 5-volt reference circuit that is 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.
Conditions for Running the DTC
| • | DTCs P0601, P0602, P0606, P1517, or P1518 are not set. |
| • | The ignition switch is in the crank or the run position. |
| • | The ignition voltage is greater than 5.23 volts. |
Conditions for Setting the DTC
| • | The APP sensor 2 voltage is less than 0.83 volts or greater than 4.81 volts. |
| • | 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 water intrusion occurs, multiple DTCs could be set with no DTC circuit or component conditions found during diagnostic testing. |
| • | When the TAC module detects throttle movement with a DTC P1275 set, a DTC P1276 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 that 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. Keep this in mind when reviewing the stored information, Capture info. |
| • | For an intermittent, refer to Intermittent Conditions . |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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TP sensor 2 and the APP sensor 2 share a common 5-volt reference source. Diagnose DTC P1220 first, if this DTC is also set.
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This test determines whether the TAC module can recognize a change in signal voltage.
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There are three separate 5-volt reference sources within the TAC module. TP sensor 1 and APP sensor 1 share one 5-volt reference source, TP sensor 2 and APP sensor 2 share another common 5-volt reference source and APP sensor 3 uses the third by itself. This test determines whether the signal circuit is shorted to any one of the 5-volt reference circuits. If a short exists, the corresponding sensor voltage will be pulled low.
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The previous step found the signal circuit and a 5-volt reference circuit shorted together. This test isolates whether the short is in the harness or within the TAC module.
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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 that 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. Keep this in mind when reviewing the stored information, 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 | |
|
Important: If DTC P1518 or P1220 is also set, refer to Diagnostic Trouble Code (DTC) List and diagnose the applicable DTC first.
Does the scan tool indicate APP sensor 2 voltage within the specified values | 3.90-4.81 V | Go to Step 3 | Go to Step 6 | |
3 | Fully depress the accelerator pedal to the wide open throttle (WOT) position. Does the scan tool indicate APP sensor 2 voltage within the specified values? | 0.83-2.9 V | Go to Step 4 | Go to Step 6 |
4 |
Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 5 |
5 | Slowly depress the accelerator pedal to wide open throttle (WOT) and then slowly return the pedal to closed throttle while observing the DTC status. Did the scan tool indicator this DTC failed this ignition during the above test? | -- | Go to Step 21 | Go to Diagnostic Aids |
6 |
Does the DMM indicate APP sensor 2 signal voltage within the specified values? | 3.94-6.06 V | Go to Step 11 | Go to Step 7 |
7 |
Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 8 |
8 | With a DMM, test the APP sensor 2 signal circuit for an open or for high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 9 |
9 | With a DMM, test the APP sensor 2 signal circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 10 |
10 | With a DMM, test for a short between the APP sensor 2 signal circuit and all other TAC module circuits. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 23 |
11 | With a DMM, test the APP sensor 2 5-volt reference circuit for voltage. Does the DMM indicate voltage within the specified values? | 3.94-6.06 V | Go to Step 16 | Go to Step 12 |
12 |
Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 13 |
13 | With a DMM, test the APP sensor 2 5-volt reference circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 14 |
14 | With a DMM, test the APP sensor 2 5-volt reference circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 15 |
15 | With a DMM, test for a short between the APP sensor 2 5-volt reference circuit and all other TAC module circuits. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 23 |
16 | With a DMM connected between the APP sensor 2 low reference circuit and the APP sensor 1 low reference circuit, measure resistance. Does the DMM indicate resistance within the specified values? | 0-5 ohms | Go to Step 18 | Go to Step 17 |
17 |
Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 23 |
Does the scan tool indicate APP sensor 2 voltage at the specified value? | 0 V | Go to Step 19 | Go to Step 23 | |
Did the scan tool indicate a change in voltage in any of the parameters observed during the above test? | -- | Go to Step 20 | Go to Step 21 | |
Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 23 | |
21 | 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 25 | Go to Step 22 |
22 | Replace the APP sensor assembly. Refer to Accelerator Pedal Position Sensor Replacement . Did you complete the replacement? | -- | Go to Step 25 | -- |
23 | Inspect for poor connections at the harness connector 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 25 | Go to Step 24 |
24 | Replace the TAC module. Refer to Electronic Throttle Actuator Control Module Replacement . Did you complete the replacement? | -- | Go to Step 25 | -- |
25 |
Does the DTC run and pass? | -- | Go to Step 26 | 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 | ||
