Refer to
Cell 20: TP and APP Sensors
for complete circuit details.
Circuit Description
The Accelerator Pedal Position (APP) sensor is mounted on the accelerator pedal assembly. The sensor is actually three individual Accelerator Pedal Position sensors within one housing. Three separate signal, ground and 5 volt reference circuits connect the Accelerator Pedal Position Sensor assembly and the Throttle Actuator Control (TAC) Module. Each sensor has a unique functionality. The APP sensor 1 signal increases as the accelerator pedal is depressed, from below 1.0 volt at 0% pedal travel (pedal at rest) to above 2.0 volts at 100% pedal travel (pedal fully depressed). The APP sensor 2 signal decreases from above 4.0 volts at 0% pedal travel to below 2.9 volts at 100% pedal travel. The APP sensor 3 signal decreases from around 3.8 volts at 0% pedal travel to below 3.1 volts at 100% pedal travel. Observe that the signal circuits for APP Sensor 2 and APP Sensor 3 pull up to 5 volts and the APP Sensor 1 signal circuit referenced to ground within the TAC Module.
Conditions for Running the DTC
| • | DTCs P0601, P0602, P0606, P1517, 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
| • | The APP sensor 2 voltage ranges between 0.83 volts and 4.81 volts |
| • | All of the above conditions met for less than 1 second. |
Action Taken When the DTC Sets
| • | The PCM stores the DTC information into memory when the diagnostic runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Freeze Frame and/or Failure Records. |
| • | If no other TAC System DTCs are set, the TAC System operates normally. If certain TAC System DTCs are set at the same time, the TAC system commands the engine to operate in a reduced engine power mode. The TAC system may command the engine to shut down. |
Conditions for Clearing the DTC
| • | A last test failed, or current DTC, clears when the diagnostic runs and does not fail. |
| • | A history DTC will clear after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic. |
| • | Use a scan tool in order to clear the DTC. |
Diagnostic Aids
Important:
• Remove any debris from the PCM\TAC module connector surfaces before
servicing the PCM\TAC module. Inspect the PCM\TAC module connector gaskets
when diagnosing/replacing the modules. Ensure that the gaskets are
installed correctly. The gaskets prevent contaminate intrusion into
the PCM\TAC modules. • For any test that requires probing the PCM or a component
harness connector, use the Connector Test Adapter Kit J 35616
. Using this kit prevents damage
to the harness/component terminals. Refer to
Using Connector Test Adapters
in Wiring Systems.
| • | The following may cause an intermittent: |
| - | Poor connections; Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems. |
| - | Corrosion |
| - | Mis-routed harness |
| - | Rubbed through wire insulation |
| - | Broken wire inside the insulation |
| - | Inspect the TAC module connectors for signs of water intrusion. This causes intermittent DTCs. |
| • | The APP sensor 1 and the TP sensor 1 5.0 volt reference circuits are internally connected within the TAC. |
| • | The APP sensor 2 and the TP sensor 2 5.0 volt reference circuits are internally connected within the TAC. |
| • | When the TAC module detects throttle movement with a DTC P1280 set, a DTC P1281 also sets. |
| • | When the TAC module detects a condition within the TAC System, more than one TAC System related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing one individual condition may correct more than one DTC. Keep this in mind when reviewing captured DTC info. |
| • | For an intermittent condition, refer to Symptoms . |
Test Description
The numbers below refer to the step numbers on the Diagnostic Table.
-
TP sensor 2 and the APP sensor 2 share a common 5.0 volt reference source. Diagnosis DTC P1220 first if it is also set.
-
This test determines whether or not the TAC Module can recognize a change in signal voltage.
-
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.
-
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.
-
When a condition is detected within the TAC System, more than one TAC System related DTC may set. This is due to the many redundant tests run continuously on this system. It is possible that locating and repairing one individual condition may correct more than one DTC. Keep this in mind when reviewing captured DTC info.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
|
Important: If DTC P1518 or P1220 is also set, refer to the appropriate DTC for further diagnosis.
Is the voltage within the specified range? | 3.90-4.81V | |||
3 | Fully depress the accelerator pedal. Is the voltage within the specified range? | 0.83-2.9V | ||
4 |
Does the harness movement cause this DTC to set? | -- | ||
5 |
Did this DTC set? | -- | Go to Diagnostic Aids | |
6 |
Is the voltage within the specified range? | 3.94-6.06V | ||
7 |
Is any voltage present? | -- | ||
8 | Test the harness of the APP Sensor 2 signal circuit for continuity using the DMM J 39200 . Is continuity indicated? | -- | ||
9 | Test the harness for continuity between the APP Sensor 2 signal circuit and the battery ground using the DMM J 39200 . Is continuity indicated? | -- | ||
10 | Test the harness for continuity between the APP Sensor 2 signal circuit, at the TAC harness connector, and all other circuits in both TAC module connectors using the DMM J 39200 . Is continuity indicated? | -- | ||
11 | Measure the voltage from the APP Sensor 2 5 volt reference circuit in the APP Sensor harness connector to battery ground using the DMM J 39200 . Is the voltage within the specified range? | 3.94-6.06V | ||
12 |
Is any voltage present? | -- | ||
13 | Test the harness for continuity of the APP Sensor 2 5 volt reference circuit using the DMM J 39200 . Is continuity indicated? | -- | ||
14 | Test the harness for continuity between the APP Sensor 2 5 volt reference circuit and battery ground using the DMM J 39200 . Is continuity indicated? | -- | ||
15 | Test the harness for continuity between the APP Sensor 2 5 volt reference circuit, at the TAC harness connector, and all other circuits in both TAC module connectors using the DMM J 39200 . Is continuity indicated? | -- | ||
16 | Measure the resistance from the APP Sensor 2 ground circuit in the APP Sensor harness connector to the APP sensor 1 ground circuit using the DMM J 39200 . Is the resistance within the specified range? | 0-5ohms | ||
17 |
Is continuity indicated? | -- | ||
Does the scan tool indicate the specified voltage? | 0V | |||
Are any of these other sensor voltages affected when the APP Sensor 2 signal circuit is grounded? | -- | |||
Is continuity indicated? | -- | |||
21 | Repair the harness/connections as necessary. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |
22 | Repair the short to voltage in the 5 volt reference circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |
23 | Repair the open/high resistance in the 5 volt reference circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |
24 | Repair the short to ground in the 5 volt reference circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |
25 | Repair the short to voltage in the signal circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |
26 | Repair the open/high resistance in the signal circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |
27 | Repair the short to ground in the signal circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |
28 | Repair the open/high resistance in the ground circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |
29 | Repair the circuits that are shorted together. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |
30 |
Did you find and correct the condition? | -- | ||
31 | Replace the accelerator pedal assembly. Refer to Accelerator Pedal Position Sensor Replacement . Is the action complete? | -- | -- | |
32 |
Did you find and correct the condition? | -- | ||
33 | Replace the TAC Module. Refer to Powertrain Control Module/Throttle Actuator Control Module Replacement . Is the action complete? | -- | -- | |
34 |
Does the scan tool indicate that this test ran and passed? | -- | ||
Select the Capture Info option and the Review Info option using the scan tool. Does the scan tool display any DTCs that you have not diagnosed? | -- | Go to the applicable DTC table | System OK |
