Accelerator Pedal Position (APP) Sensor
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 5.0 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 1.1 volt at 0% pedal travel (pedal at rest) to above 2.1 volts at 100% pedal travel (pedal fully depressed). The APP sensor 2 signal decreases from above 3.9 volts at 0% pedal travel to below 2.9 volts at 100% pedal travel. The APP sensor 3 signal decreases from above 3.2 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 5.0 volts and the APP Sensor 1 signal circuit pull to ground within the TAC Module.
Conditions for Setting the DTC
| • | DTCs P1517, P1518 not set. |
| • | Ignition switch in the crank or run position. |
| • | Ignition voltage greater than 5.23 volts. |
| • | APP sensor #3 disagrees with APP sensor #1 by more than 13.0% and APP sensor #3 disagrees with APP sensor #2 by more than 13.0%. |
| • | All 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 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 either defaults to a Reduced Engine Power Mode or to a more tightly restricted mode of operation if the TAC determines that limited safe operation is possible, or the TAC commands the engine to shut down. |
Conditions for Clearing the MIL/DTC
| • | 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. |
| • | A last test failed (Current DTC) will clear when the diagnostic runs and does not fail. |
| • | The PCM battery voltage is interrupted. |
| • | Use a scan tool in order to clear the MIL/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.
| • | The following may cause an intermittent: |
| - | Poor connections: Check for adequate terminal tension. Refer to Body and Accessories/Wiring Systems for proper procedure. |
| - | Corrosion |
| - | Mis-routed harness |
| - | Rubbed through wire insulation |
| - | Broken wire inside the insulation |
| - | Inspect the TAC module connectors for signs of water intrusion. When this occurs, multiple DTCs should set and you cannot locate any circuit or component problems. |
| • | The APP and TP sensor 5.0 volt reference circuits are internally connected within the TAC. Inspect the 5.0 volt reference circuits at the APP and the TP sensors for an open, a ground, or a short to a voltage. TP and APP sensor DTCs will set. |
| • | For an intermittent condition, refer to Symptoms . |
| • | If you complete a repair and the DTC is cleared using a scan tool on the same ignition cycle, the default action will not clear until an ignition cycle has occurred. |
| • | When the TAC module detects a problem 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 problem may correct more than one DTC. Keep this in mind when reviewing captured DTC info. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This step determines if the malfunction is present. For any test that requires probing the PCM or component harness connectors, use the Connector Test Adapter Kit J 35616 . Using this kit will prevent any damage to the harness connector terminals.
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Using the Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can also help determine how many ignition cycles the diagnostic reported a pass and/or a fail. Operate the vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that you observed. This will isolate when the DTC failed. For any test that requires probing the PCM or component harness connectors, use the Connector Test Adapter Kit J 35616 . Using this kit prevents any damage to the harness connector terminals.
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An intake air temperature above 139°C (282°F) indicates that the PCM and IAT wiring are OK.
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An intake air temperature above 139°C (282°F) indicates that the PCM and IAT signal circuit is OK.
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Disconnecting the PCM allows using the DMM J 39200 in order to check continuity of the circuits. This aids in locating an open or a shorted circuit.
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Disconnecting the PCM allows using the DMM J 39200 in order to check continuity of the circuits. This aids in locating an open or a shorted circuit.
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Inspect for proper terminal tension/connections at the PCM harness before replacing the PCM.
Step
| Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
Is the IAT at the specified value? | -39°C (-38°F) | |||
Does the scan tool indicate that this diagnostic failed this ignition? | -- | Go to Diagnostic Aids | ||
Is the IAT at the specified value? | 140°C (284°F) | |||
Jumper the IAT signal circuit to a known good ground. Is the IAT at the specified value? | 140°C (284°F) | |||
Is the IAT sensor signal circuit open? | -- | |||
7 | Repair the IAT sensor signal circuit. Refer to Wiring Repairs in wiring systems. Is the action complete? | -- | -- | |
Is the IAT sensor ground circuit open? | -- | |||
9 | Replace the IAT sensor. Refer to Intake Air Temperature Sensor Replacement . Is the action complete? | -- | -- | |
10 | Repair the IAT sensor ground circuit. l circuit. Refer to Wiring Repairs in wiring systems. Is the action complete? | -- | -- | |
11 |
Important:: Program the replacement PCM. Refer to Powertrain Control Module Replacement . Replace the PCM. Is the action complete? | -- | -- | |
12 |
Does the scan tool indicate that this test ran and passed? | -- | ||
13 | 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 |
