Google Sheet script getValues and when find the given value, replace the value of the above row

Question

How can I modify the script below to read the values in a column, but only read the values of the specified cells: L9, L10 ... L18, L19 .... L27, L28 .... (two by two jumping eight, to the end of the column L2000) and when find the value "1" in one of those cells, then replace the value that is 4 lines up with "FALSE"?

e.g. if cell L19 is found the number 1, then replace the value of cell L15 with the word "FALSE" ... and if cell L28 is found the number 1, then replace the value of cell L24 with the word "FALSE"

var ss = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("ABC"); 
var lastrow = ss.getLastRow(); 
var range = ss.getRange(9, 12, lastrow - 1, 1); 
var data = range.getValues(); 
for (var i=0; i < data.length; i++) { 
  if (data[i][0] == "1") { 
    data[i][0] = "FALSE"; 
  } 
} 
range.setValues(data); 

Answer 1

Add another counter to loop: Try Modifying

From:

var range = ss.getRange(9, 12, lastrow - 1, 1); 
var data = range.getValues(); 
   for (var i=0; i < data.length; i++) { 
     if (data[i][0] == "1") { 
      data[i][0] = "FALSE"; 
    } 
   } 

To:

var range = ss.getRange(5, 12, lastrow+5, 1); 
var data = range.getValues(); 
var m= 0;
for (var i=4; i < data.length; ) { 
  if (data[i][0] == "1") {
    data[i-4][0] = "FALSE";
  }
  m++;
  if (m == 2) {
    m=0; 
    i = i + 8;
  } else {
    i++;
  }
}

Answer 2

My take on what the loop should become:

var range = ss.getRange(9, 12, lastrow - 1, 1);
var data = range.getValues();
var i = 4,
    // Subtract 1 here because we compare both i and i+1 in the same loop body
    len = data.length - 1;
while (i < len) {
  // Check the value of the first row in the subset.
  if (data[i][0] == 1) {
    data[i - 4][0] = "FALSE";
  }
  // Check the next row in the subset.
  if (data[++i][0] == 1) {
    data[i - 4][0] = "FALSE";
  }
  // Advance to the next subset.
  i += 8;
}