Circuit Description
The commanded throttle position is compared to the actual throttle position based on accelerator pedal position and possibly other limiting factors. Both values should be within a calibrated range of each other. The powertrain control module (PCM) continuously monitors the commanded and actual throttle positions. This diagnostic trouble code (DTC) sets if the values are greater than the calibrated range.
Conditions for Running the DTC
The ignition is ON.
Conditions for Setting the DTC
The difference between the predicted and the actual throttle position is more than a calibrated amount.
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 turns OFF the MIL after 3 consecutive drive trips that the diagnostic runs and passes. |
| • | A History DTC clears after 40 consecutive warm-up cycles in which there are no failures reported of this diagnostic or any other emission related diagnostic. |
| • | The scan tool clears the MIL/DTC. |
Diagnostic Aids
The throttle valve is spring loaded to a slightly open position. The throttle valve should be open approximately 20 percent. This is referred to as the rest position. The throttle valve should not be completely closed nor should they be open any more than the specified amount. The throttle valve should move open and to the closed position without binding under the normal spring pressure. The throttle should NOT be free to move open or closed WITHOUT spring pressure. Replace the throttle body if any of these conditions are found.
Important: Operating the throttle blade with the Throttle Blade Control function of the scan tool may cause additional DTCs to set. Do not attempt to diagnose DTCs set during this function.
The scan tool has the ability to operate the throttle control system using Special Functions. Actuate the throttle valve using the throttle blade control function located in the TAC System menu. This function will operate the throttle valve through the entire range in order to determine if the throttle body and system operate correctly.
Check for the following conditions:
| • | Use the J 35616 Connector Test Adapter Kit for any test that requires probing the PCM harness connector or a component harness connector. |
| • | Poor connections at the PCM or at the component--Inspect the harness connectors for a poor terminal to wire connection. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems for the proper procedure. |
| • | If the condition is intermittent, refer to Intermittent Conditions . |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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The throttle valve is spring loaded in a slightly open position and should move in either direction without binding. The throttle valve should always be under spring pressure.
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When the ignition is turned ON, the PCM operates the throttle control motor to verify the integrity of the system prior to start-up. This can be seen by the momentary flash of the test lamp as the ignition is turned ON.
Step | Action | Values | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views | ||||||||||
1 | Did you perform the Diagnostic System Check - Engine Controls? | -- | Go to Step 2 | |||||||
2 | Are DTCs P0120, P0220, P2120, P2125, P2135 and P2138 also set? | -- | Go to Step 3 | |||||||
3 |
Important: The throttle angle and pedal angle may not correspond during this procedure.
Does the TP sensor 1 and 2 angle parameters increase as the pedal is applied and decrease as the pedal is released? | -- | Go to Step 4 | Go to Step 5 | ||||||
4 |
Did the DTC fail this ignition? | -- | Go to Step 5 | Go to Diagnostic Aids | ||||||
5 |
Does the test lamp illuminate on both sides of the fuse? | -- | Go to Step 6 | Go to Step 16 | ||||||
6 |
Does the test lamp illuminate on both sides of the fuse? | -- | Go to Step 22 | Go to Step 7 | ||||||
7 |
Does the test lamp illuminate? | -- | Go to Step 8 | Go to Step 23 | ||||||
Did you find any of these conditions with the throttle body? | -- | Go to Step 24 | Go to Step 9 | |||||||
9 |
Important: The test lamp may momentarily flash when testing these circuits. This is considered normal.
Did the test lamp illuminate and remain illuminated on either circuit? | -- | Go to Step 13 | Go to Step 10 | ||||||
10 |
Important: The test lamp may momentarily flash when testing these circuits. This is considered normal. Probe the TAC motor control 1 and 2 circuits with the test lamp connected to battery positive. Did the test lamp illuminate and remain illuminated on either circuit? | -- | Go to Step 14 | Go to Step 11 | ||||||
Does the test lamp flash ON, then OFF? | -- | Go to Step 12 | Go to Step 15 | |||||||
12 | Measure the voltage from the motor control circuits to a good round with a DMM. Refer to Circuit Testing in Wiring Systems. Is the voltage on both circuits more than the specified value? | 12 V | Go to Step 18 | Go to Step 15 | ||||||
13 |
Does the test lamp illuminate? | -- | Go to Step 20 | Go to Step 19 | ||||||
14 |
Does the test lamp illuminate? | -- | Go to Step 21 | Go to Step 19 | ||||||
15 |
Did you find and correct the condition? | -- | Go to Step 26 | Go to Step 19 | ||||||
16 | Test the ECM ignition 1 voltage 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 26 | Go to Step 17 | ||||||
17 | Test the motor control 1 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 26 | Go to Step 24 | ||||||
18 | Test for a poor connection or terminal tension at the throttle body connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 26 | Go to Step 24 | ||||||
19 | Test for a poor connection or terminal tension at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 26 | Go to Step 25 | ||||||
20 | Repair the short to voltage on the circuit where the test lamp remained illuminated. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 26 | -- | ||||||
21 | Repair the short to ground on the circuit where the test lamp remained illuminated. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 26 | -- | ||||||
22 | Repair the short to voltage on the ETC ignition 1 voltage circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 26 | -- | ||||||
23 | Repair the open or high resistance in the ETC ignition 1 voltage circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 26 | -- | ||||||
24 | Replace the throttle body assembly. Refer to Throttle Body Assembly Replacement . Did you complete the replacement? | -- | Go to Step 26 | -- | ||||||
25 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 26 | -- | ||||||
26 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 27 | ||||||
27 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |||||||
