Circuit Description
The throttle actuator control assembly has two throttle position (TP) sensors mounted within the assembly. The powertrain control module (PCM) provides individual signal, ground, and 5-volt reference circuits to each sensor. Both sensors operate within a voltage range between 0.35-4.65 volts. When the throttle is opened from 0 to 100 percent, one sensor signal voltage increases while the other decreases. The signal circuit for TP sensor 1 is referenced to ground, and the signal circuit for TP sensor 2 is pulled up to 5 volts within the PCM.
Conditions for Running the DTC
| • | The ignition is ON. |
| • | DTCs P1120, P1220, P1635, or P1639 are not set. |
| • | The ignition voltage is greater than 5.23 volts. |
Conditions for Setting the DTC
The difference between the TP sensor 1 and TP sensor 2 exceeds a predetermined value.
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame and/or the Failure Records. |
| • | The control module commands the TAC system to operate in the Reduced Engine Power mode. |
| • | A message center or an indicator displays Reduced Engine Power. |
| • | Under certain conditions the control module commands the engine OFF. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn OFF the malfunction indicator lamp (MIL) during the third consecutive trip in which the diagnostic has run and passed. |
| • | The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction. |
| • | The DTC can be cleared by using a scan tool. |
Diagnostic Aids
If DTC is determined to be intermittent, refer to Intermittent Conditions .
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This step checks the integrity of the 5-volt reference and ground circuits of the TP sensors.
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This step determines if the 5-volt reference circuit or the sensor ground circuit is the cause of the DTC.
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If the scan tool displays 100 percent for the TP sensor 1 and the TP sensor 2 angle, this indicates that the TP sensor signal circuits are not the cause of the DTC.
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This step checks for excessive resistance in the TP sensor 5-volt reference circuit between the TP sensor harness connector and the PCM harness connector.
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This step checks for excessive resistance in the TP sensor ground circuit between the TP sensor harness connector and the PCM harness connector.
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This step checks for the TP sensor signal circuits for being shorted to another circuit in the PCM wiring harness between the PCM and the TP sensor wiring harness.
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When the PCM detects a problem within the throttle control system, more than one 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 Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |
2 | Using a scan tool, observe the DTC information. Is DTC P1635 or P1639 also set? | -- | Go to Step 3 | |
3 |
Does the scan tool indicate Disagree? | -- | Go to Step 6 | Go to Step 4 |
4 |
Important: Removing the ETC fuse will set additional DTCs. Does the scan tool indicate Disagree while rotating the throttle blade? | -- | Go to Step 6 | Go to Step 5 |
5 |
Does the DTC fail this ignition? | -- | Go to Step 15 | Go to Intermittent Conditions |
Does the DMM display a voltage within the specified range for both measurements? | 4.9-5.1 V | Go to Step 8 | Go to Step 7 | |
Test the voltage on the 5-volt reference circuit for TP sensor 1 and TP sensor 2 to a battery ground with a DMM. Does the DMM display a voltage within the specified range? | 4.9-5.1 V | Go to Step 10 | Go to Step 9 | |
Observe the TP sensor 1 and TP sensor 2 angle on the scan tool. Does the scan tool indicate both sensors at the specified value? | 100% | Go to Step 12 | Go to Step 11 | |
Test the 5-volt reference circuit of the TP sensor 1 and TP sensor 2 for high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 13 | |
Test the low reference circuit of the TP sensor 1 and TP sensor 2 for high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 13 | |
Test the signal circuit of the TP sensor 1 and TP sensor 2 for high resistance. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 13 | |
12 | Replace the throttle body assembly. Refer to Throttle Body Assembly Replacement . Did you complete the replacement? | -- | Go to Step 15 | -- |
13 | Test for poor connections and/or terminal tension at the TP sensor and at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 14 |
14 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 15 | -- |
15 |
Does the DTC run and pass? | -- | Go to Step 16 | 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 |
