Diagnostic Method

Calculate the max. value of the amount of output voltage variation from fuel level sensor and cumulative value during 12.8 seconds. Comparing the max value and cumulative value with the threshold value, and judge OK when the both do not go over the threshold value. Otherwise, when one of them goes over the threshold, count the counter up. Judge the ECM is troubled when the counter increased 4 times in a row.

Fig 1: Fuel Level Sensor Voltage Output Graph

Courtesy of SUBARU OF AMERICA, INC.

• Abnormality Judgment 

  Judge NG when the malfunction criteria below are completed.

• Judgment Value 
  JUDGMENT VALUE (ABNORMALITY JUDGMENT)
  
  

  Malfunction Criteria	Threshold Value
  Integrated times of the condition reaching follows, DVFLMAX ≥ 0.88 V SUMVFL ≥ 14.08 V DVFLMAX is max. value of sensor output during 12.8 seconds. SUMVFL is cumulative value of sensor output deviation during 12.8 seconds.	≥ 4 times

Time Needed for Diagnosis  : 12.8 seconds x 4 times

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

• Normality Judgment 

  Judge OK and clear the NG when all the malfunction criteria below are completed.

• Judgment Value 
  JUDGMENT VALUE (NORMALITY JUDGMENT)
  
  

  Malfunction Criteria	Threshold Value
  DVFLMAX	< 0.88 V
  SUMVFL	< 14.08 V