My 2002 Toyota Land Cruiser has, for past few weeks, failed to start intermittently and it appears that the security system is failing to recognize valid key. Dealership has had it on two occasions and failed to rectify. Ruled out keys as problem and focused on electrical. When it occurs, the engine will turn over but not allow to start (fuel injectors?). There is seemingly no pattern to when this problem will occur, but it leaves me with a vehicle I can't rely on. The security light fails to go out when ignition is turned. Any ideas or thoughts will be greatly appreciated.