I have a 2000 Jeep Cherokee XJ 4.0 I6 motor with a automatic trans. I recently replaced the transmission and starter on the jeep. I connected the battery with no key in the ignition or anything the jeep turns over but it will not start. So I unplugged the ignition wire running to the starter thinking it may be that but the same problem occurs. When I turn the key in the ignition to the run position the jeep will start and run. Until I disconnect the battery because it will not stop trying to turn over when its connected. Please help trying to sell this week.

 

Start by pulling the starter motor relay. See if it still happens. Report back.