Not one for replacing parts till problem solved, so ended up with 2 Nitro's both 2007 3.7 Nitro #1, bought it, repaired a small amount of front end damage, drove it about 1000 miles everything fine, one morning wouldn't crank, thought it might be security system, only had 1 key with it , just key, no fob attached, security light goes out, you can jump solenoid on starter, motor spins but no start, have another 2007 nitro #2 it had 2 fobbed keys, I replaced motor in it , thought fuel pump had quit but turned out to be relay in TIPM, took TIPM from it put in no crank Nitro #1 . started right up [ with jumper on fuel pump fuse ] started it about 5 times over a week or so then no crank again. put TIPM back in other Nitro #2 now it won't crank, have looked at wiring diagram for ign switch and see there are a couple wires that send signals to TIPM . Was going to have TIPM's repaired on both vehicles, but not if something in system would damage it. but what would be causing the TIPM to go bad from one vehicle to next. don't think any mods have been made to either vehicle as far as sound, or alarm systems, ect , is there a way to check and see what sensors are not sending signals to ok a start? 2 Nitro's dead ----- #1 has 140,000 miles , Nitro #2 131,000 miles, when I bought #2 it had spit a rocker arm through valve cover, thought rocker locks would be a fix, but found it had dropped valve seat, so cheaper to put in another motor , got one with 115,000 miles from 05 cherokee. installed it after swapping all the different items [ also had to drill hole through head to be able to use EGR valve] . AC worked but cooling fan on radiator wouldn't run, think it was TIPM on that problem also, then no fuel pressure, which was TIPM. now it won't crank. can't get any help or advice even from local Dodge Mechanics.