Hello I am new to this forum. My brother in law has a 99 cherokee. Sometimes the check engine light comes on for a sec then a crossed out key symbal comes on. Sometimes it will not even turn over when you try to start it. Also the speedo only work intermittantly. I don't really know all the facts. He took it to the Jeep dealership. They replaced the coded key and box. Also they replaced the computer that controls the key. It still does the same thing every once in a while. I am a diesel tech so I am not retarted when it comes to cars. I however did not want to mess with this problem. If anyone has heard of this problem at all or can tell me anything about the computer or harnesses that run the coded key and or speedo please give me some info! If anyone wants more info let me know thanks!