DTC P0604: Internal Control Module Random Access Memory (Ram) Error

Detect the function abnormality of the micro-computer (RAM).

Judge NG when either the main CPU normal RAM or sub CPU normal RAM is abnormal. Judge OK when both of them are normal.

At initial routine, write the data to all area of RAM. Judge OK when same data can be read out, and judge NG when same data cannot be read out.

Perform the diagnosis in the initial routine.

Perform the diagnosis immediately after IG key SW is turned ON.

• Abnormality Judgment 

  Judge NG when the malfunction criteria below are completed.

  Judgment Value 

  MALFUNCTION CRITERIA AND THRESHOLD VALUE CHART
  
  

  Malfunction Criteria	Threshold Value
  Main CPU normal RAM abnormality
  Write 5AA5A55A, and read out. (All area of RAM)	Cannot be read out 5AA5A55A.
  Or write A55A5AA5, and read out. (All area of RAM)	Cannot be read out A55A5AA5.
  Sub CPU normal RAM abnormality.
  Write 5AA5, and read out. (All area of RAM)	Cannot be read out 5AA5.
  Or write A55A, and read out. (All area of RAM)	Cannot be read out A55A.

  Time Needed for Diagnosis:  100 milliseconds

  Malfunction Indicator Light Illumination:  Illuminates as soon as malfunction occurs.

• Normality Judgment 

  Judge NG when the malfunction criteria below are completed.

  Judgment Value 

  MALFUNCTION CRITERIA AND THRESHOLD VALUE CHART
  
  

  Malfunction Criteria	Threshold Value
  Main CPU normal RAM abnormality
  Write 5AA5A55A, and read out. (All area of RAM)	Cannot be read out 5AA5A55A.
  Or write A55A5AA5, and read out. (All area of RAM)	Cannot be read out A55A5AA5.
  Sub CPU normal RAM abnormality.
  Write 5AA5, and read out. (All area of RAM)	Cannot be read out 5AA5.
  Or write A55A, and read out. (All area of RAM)	Cannot be read out A55A.

• When the OK idling cycle was completed 40 times in a row
• When "Clear Memory" was performed

• When the OK driving cycle was completed 3 times in a row
• When "Clear Memory" was performed

None

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