A 4.0l HO spfi Jeep gets it's coil positive voltage directly from the A.S.D. relay, which is full battery voltage. On older point type ign. systems, you should have battery voltage during crank only, and dropped through a ballest resister in the run position. This can be wired using a standard I.S.O. relay to by-pass the ballest in the crank position, by robbing power from the starter motor. A cheap place for ballest resistors is from an older Dodge, about 2 bucks, and made of ceramic.