Change Gui Textre to another overtime? and reset script when player passes through trigger

Well Basically i want a Gui Texture to change to another gui texture 1 min later, and then to another Gui Texture another 1 min later, (max 2 times) and when u walk through a trigger the script resets happening all over again.

SO e.g. green icon goes to yellow, yellow icon goes to red (1 min intervals) player walks through a Trigger, it all resets going back to the first Gui texture happening all over again.

hope i worded this correctly. any ideas? i wouldnt know how to start a script like this.

You can set a timer to loop through the textures in Update, and reset this loop in OnTriggerEnter - like this (trigger script):

var gTexture: GUITexture; // drag the GUITexture here
var textures: Texture2D[]; // define the textures here
var interval: float = 60.0; // interval in seconds

private var timer: float = 0.0;
private var curTex: int = 0;

function Update(){
  timer -= Time.deltaTime; // decrement timer
  if (timer < 0.0) SetTexture(); // set the texture

function SetTexture(){
  gTexture.texture = textures[curTex++]; // assign current texture and advance pointer
  curTex = curTex % textures.length;  // return to first one if passed the last 
  timer = interval; // reset timer

function OnTriggerEnter(){
  curTex = 0;   // reset texture pointer...
  SetTexture(); // assign current texture and reset timer