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Home >> Subaru >> 2004 >> Forester XT, Standard >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Diagnostic Trouble Code (DTC) Detecting Criteria (H4DOTC) >> Diagnostic Trouble Code (DTC) Detecting Criteria >> DTC P0851: Neutral Switch Input Circuit Low (Mt Model)
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DTC P0851: Neutral Switch Input Circuit Low (Mt Model)

  1. OUTLINE OF DIAGNOSIS 

    Judge the open or short circuit of the neutral SW.

    Judge NG when there is no change in the neutral SW even if the driving shift was applied. (There is neutral SW ON/OFF inversion from the vehicle speed and engine speed.)

  2. ENABLE CONDITION 
    ENABLE CONDITION CHART

    Secondary Parameters Enable Conditions
    Ignition switch ON
    Battery voltage "GREATER THAN EQUAL TO" 10.9 V
    After starting the engine 2 seconds or more
    Starter switch OFF
  3. GENERAL DRIVING CYCLE 

    Perform the diagnosis continuously in 2 seconds or more after starting the engine.

  4. DIAGNOSTIC METHOD 

    Judge NG when the malfunction criteria below are completed 3 time or more after the neutral SW change. And clear NG if there is change in the neutral SW.

    Judgment Value 

    JUDGMENT VALUE CHART

    Malfunction Criteria Threshold Value
    Neutral switch signal (while changing from a to b below) OFF continues
    Driving condition change
    1. Vehicle speed = 0 km/h (0 MPH) & engine speed 600 - 900 rpm
    2. Vehicle speed "GREATER THAN EQUAL TO" 64 km/h (40 MPH) & engine speed 1600 - 2550 rpm
    a) to b)

    Time Needed for Diagnosis:  3 monitoring

    Malfunction Indicator Light Illumination:  Illuminates when malfunction occurs in 2 continuous driving cycles.

  5. DTC CLEAR CONDITION 
    • When the OK idling cycle was completed 40 times in a row
    • When "Clear Memory" was performed
  6. MALFUNCTION INDICATOR LIGHT CLEAR CONDITION 
    • When the OK driving cycle was completed 3 times in a row
    • When "Clear Memory" was performed
  7. FAIL SAFE 

    Cruise control command: Not allowed to command cruise control

  8. ECM OPERATION AT DTC SETTING 

    Memorize the freeze frame data. (For test mode $02)