Lately, I've been having problems starting up my 4runner. Once it's running, everything runs perfect...no problems whatsoever. But sometimes, when i go to turn the key, it'll just make a "click" noise, sounds like a relay or something, and nothing else will happen. So if i sit there for a second, try it again a few times, it will eventually crank and start. This is an intermittent problem, it'll be gone for a week, and then come back. If anyone has any suggestions as to what i should check/replace first, i'd appreciate it. TIA