1988 Jeep Wrangler shuts down when key is released from start position?

I have an 88 Jeep Wrangler. When the key is turned into the start position the engine will start. As soon as the key is released into the on position the engine will shut down. Electrical power is still available. It will stay running as long as the key remains in the start position. Could this be the ignition module?|||Turn ign to on. Check with test light for power at the ign switch terminal that feeds ignition. Sounds as if no power getting to ignition system.|||Ignition switch, different from the module.