Circuit Description
The powertrain control module (PCM) controls the throttle valve by applying a varying voltage to the throttle actuator control motor. The PCM monitors the actual throttle valve position using throttle position (TP) sensor 1 and 2. The PCM commands the throttle closed after the ignition is switched to the ON position. If the PCM detects that TP angle is not within a specified range, after the ignition is switched ON, or during the throttle learn procedure, or the minimum throttle position is not learned, this DTC sets.
DTC Descriptor
This diagnostic procedure supports the following DTC.
DTC P2176 Minimum Throttle Position Not Learned
Conditions for Running the DTC
| • | Before the PCM can report DTC P2176 failed, DTC P0122, P0123, P0222, P0223, P2100, P2108, P2135, and U0107 must run and pass. |
| • | The ignition is ON. |
| • | DTC P2176 runs once per drive cycle when the above conditions are met. |
Conditions for Setting the DTC
| • | The PCM detects that the TP Angle is more than 3 percent when the throttle valve is commanded closed. |
| • | The PCM detects that the TP angle is not within 5 percent of the learned minimum throttle angle. |
| • | The minimum throttle position is not learned after an PCM replacement. |
| • | Any of the above conditions are met for less than 1 second. |
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/Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
Diagnostic Aids
| • | Inspect for a condition in which the throttle valve may have been held open. |
| • | Inspect for conditions in which ice may have formed in the throttle bore. |
| • | The throttle valve is spring loaded to a slightly open position. The throttle valve should be open approximately 2-5 percent. This is referred to as the rest position. The throttle valve should not be completely closed, nor should the throttle valve be open any more than the specified amount. The throttle valve should move open and to the closed position without binding under 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. |
| • | For an intermittent condition, 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 P0121, P0122, P0123, P0221, P0222, P0223 set? | -- | Go to Scan Tool Data List | Go to Step 3 |
3 | Is DTC P2108 set? | -- | Go to DTC P2108 | Go to Step 4 |
Is DTC P2100 or P2101 set? | -- | Go to Step 5 | ||
5 |
Does the DTC reset? | -- | Go to Step 6 | Go to Step 8 |
6 | Replace the throttle body assembly. Refer to Throttle Body Assembly Replacement . Did you complete the replacement? | -- | Go to Step 7 | -- |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 8 | |
8 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |
