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Test Description

The number below refers to the step number on the diagnostic table.

  1. 5:  The throttle valve is spring loaded to a slightly open position. The throttle valve should be open approximately 3-5 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. 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.
DTC P1551 Throttle Valve Rest Position Not Reached During Learn

Step Action Yes No
Schematic Reference:  Engine Controls Schematics 
Connector End View Reference:  Engine Control Module Connector End Views  or  Engine Controls Connector End Views 
1 Did you perform the Diagnostic System Check - Vehicle? Go to Step 2  Go to Diagnostic System Check - Vehicle
2
  1. Turn ON the ignition, with the engine OFF for 30 seconds.
  2. Observe the DTC information with a scan tool.
Does the scan tool display DTC P1551 failed this ignition cycle?		 Go to Step 3  Go to Step 4 
3 Observe the DTC information.
Are DTCs P0121, P0122, P0123, P0221, P0222, P0223, P2100, P2101, or P2119 also set?		 Go to Diagnostic Trouble Code (DTC) List - Vehicle Go to Step 5 
4
  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.
Did the DTC fail this ignition?		 Go to Step 5  Go to Diagnostic Aids
5 
  1. Turn OFF the ignition.
  2. Disconnect the air intake duct at the throttle body. Refer to Air Cleaner Inlet Duct Replacement .
  3. Inspect the throttle body for the following conditions:
    • Throttle valve that is NOT in the rest position
    • Throttle valve that is binding open or closed
    • Throttle valve that is free to move open or closed WITHOUT spring pressure
Did you find any of the above conditions with the throttle body?		 Go to Step 6  Go to Diagnostic Aids
6 Replace the throttle body assembly. Refer to Throttle Body Assembly Replacement .
Did you complete the replacement?		 Go to Step 7  -
7
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.
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?		 Go to Diagnostic Trouble Code (DTC) List - Vehicle System OK
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