I have a 2000 Jeep TJ that had a blown 2.5l. My buddy pulled his 4.0 and 42rle out of his 2003 Jeep TJ to put an LS motor in. Engine and trans have about 60k miles. I have everything installed and hooked up, but It will not turn over. I replaced the stock ECU with the unit from his 2003 and still nothing. When I turn the key on after a few attempts I get a "no bus" notice. I pulled the cluster out and cleaned everything, re-installed and still nothing. Also tried the original ECU from the 2.5 and nothing. When I go to start it I hear a click behind the dash passenger side, but that's it. Is there any way I could test the ECU? Any other things that I can try? Any help would be appreciated.