How do I disable the anti theft system?

"ANTI-THEFT"............

In a nutshell: you will remove your skim module and replace your engine PCM with one programmed to your VIN but with the skim disabled. Then you will want to remove the bulb behind the "no key" dash light. Here is a youtube vid showing the process: https://www.youtube.com/watch?v=Hyzx-Hm5HNQ Here is a company that can send you a pre-programmed skim and discount the price (core value) for your old one. https://carcomputerexchange.com/jeep/grand-cherokee/1999-jeep-grand-cherokee-ecm-pcm-engine-control-module/prod_150.html Else, you will need to track down someone locally to reprogram your skim. Often its easier and more cost-effective to just order one from Car Computer Exchange or elsewhere.