Sstop the car on reaching finished line [Problem

Hi guys .. i need your your help . why my car is not stop when the car is reaching finished? .. this is my code timer.js

var pastTime : float;

var myWC : WheelCollider;

static var isFinished : boolean = false;

var guiTime : GUIText;

function Update () { var hit : WheelHit;

if(myWC.GetGroundHit(hit)){ if(hit.collider.gameObject.tag == "finished") {

isFinished = true; } }

if(!isFinished) { pastTime += Time.deltaTime; }

guiTime.text=pastTime.ToString(); }

and this is my code update to CAR.js

function Update() {
var relativeVelocity : Vector3 = transform.InverseTransformDirection(rigidbody.velocity);

 if(Timer.isFinished==false)
 GetInput();
 else throttle=0;    
 Check_If_Car_Is_Flipped();
 
 UpdateWheelGraphics(relativeVelocity);
 
 UpdateGear(relativeVelocity);

}

please guys help me .. thank you :)