Circuit Description
The Throttle Position (TP) sensor is mounted on the Air Control Valve assembly (throttle body). The sensor is actually two individual Throttle Position sensors within one housing. Two separate signal, ground and 5.0 volt reference circuits are used to connect the TP sensor assembly and the Throttle Actuator Control (TAC) Module. The two sensors have opposite functionality. The TP sensor 1 signal voltage increases as the throttle opens, from below 1.1 volts at 0 percent throttle to above 3.7 volts at 100 percent throttle. The TP sensor 2 signal voltage decreases from above 3.9 volts at 0 percent throttle to below 1.2 volts at 100 percent throttle. Observe also that the signal circuit for TP Sensor 1 is pulled up to 5.0 volts and that the signal circuit for TP Sensor 2 is pulled to ground within the TAC Module. The TAC module converts these different signals to a common scale and continuously compares them to each other to verify proper system operation.
Conditions for Running the DTC
| • | DTCs P1517, P1518 not set. |
| • | Ignition switch in the crank or run position. |
| • | Ignition voltage greater than 5.23 volts. |
Conditions for Setting the DTC
| • | TP sensor #2 disagrees with TP sensor #1 by more than 7.5 percent. |
| • | All above conditions met for less than 1 second. |
Action Taken When the DTC Sets
| • | The PCM will illuminate the malfunction indicator lamp (MIL) and the Reduced Engine Power light will be on when the diagnostic fails. |
| • | The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records. |
| • | If no other TAC System DTCs are set, the TAC System operates in Reduced Engine Power Mode. If certain TAC System DTCs are set at the same time, the TAC System either defaults 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
| • | The PCM turns the MIL OFF after 3 consecutive drive trips that the diagnostic runs and does not fail |
| • | A last test failed (current DTC) clears when the diagnostic runs and does not fail |
| • | A History DTC clears after 40 consecutive warm-up cycles, if this or any other emission related diagnostic does not report any failures |
| • | The PCM battery voltage is interrupted |
| Important:: The clear DTC information function may have to be performed twice in order to clear a Throttle Actuator Control System DTC. |
| • | Using a scan tool |
Diagnostic Aids
The following may cause an intermittent:
| • | Poor connections. Check for adequate terminal tension. Refer to Wiring Repairs 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. When this occurs, multiple DTCs should be set and no circuit or component problems can be located. |
| • | For an intermittent, refer to Symptoms . |
| • | If a repair is completed and the DTC was cleared using a scan tool on the same ignition cycle, the default action will not clear until an ignition cycle has occurred. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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Disconnect the Throttle Actuator connector before inserting fingers into the throttle bore. Re-install the air inlet duct after repairs are completed.
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When jumping either of the TP sensor signal circuits to 5.0 volts should have no effect on any of the other sensor voltages. If the jumpering effects another parameter, there is a problem within the TAC Module.
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When Jumping either TP Sensors signal circuit to ground should have no effect on any of the other sensor voltages. If the jumpering effects another parameter, there is a problem within the TAC Module.
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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.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
2 |
Does the scan tool indicate NO? | -- | ||
Important: Disconnecting the throttle actuator motor connector will cause additional DTCs to set. Does the scan tool change from NO to YES while rotating the throttle blade? | -- | |||
4 |
Does the harness movement cause this DTC to set? | -- | Go to Diagnostic Aids | |
5 | Disconnect the TAC Module connector containing the APP sensor circuits. Refer to Electronic Throttle Actuator Control Module Replacement . Are all three parameters at 0 percent? | -- | ||
6 |
Does the DMM indicate continuity? | -- | ||
7 |
Does the DMM indicate continuity? | 0.0-5.0ohms | ||
8 |
Does the DMM indicate continuity? | 0.0-5.0ohms | ||
When one signal circuit is jumped to the reference voltage, are any of the other sensor voltages affected, or does the TP sensor 1 or 2 voltage not equal the specified voltage with the jumper installed? | 3.94-6.06V | |||
When one signal circuit is jumped to ground, are any of the other sensor voltages affected, or does the TP sensor 1 or 2 voltage not equal the specified voltage with the jumper installed? | 0.0-0.1V | |||
11 | Repair the signal circuits that are shorted together. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |
12 | Repair the circuit with the high resistance. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |
13 | Check for poor connections/terminal tension at the APP sensor and at the TAC Module. Refer to Wiring Repairs in Wiring System for the proper procedure. Did you find and correct the condition? | -- | ||
14 | Replace the accelerator pedal assembly. Refer to Accelerator Pedal Position Sensor Replacement . Is the action complete? | -- | -- | |
15 | Replace the TAC Module. Refer to Electronic Throttle Actuator Control Module Replacement . Is the action complete? | -- | -- | |
16 |
Does the scan tool indicate that this diagnostic 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 |
