Took Starter out. Took it down to Autozone. It was bad. Bought new one. Put it in. WOW, was that ever a fun job to do. Had to disconnect drive shaft and exhaust pipe. Bolt on the clamp that hooks onto the exhaust pipe manifold broke. Bought new clamp at Jeep Dealer. Finally got the sucker on. Also torqued it correctly to 8mm bolts of 22 lbs (feet) each.
Put key in and dashlights came on; but now nothing won't start.
Thinking again about replacing the PCM?
PCM is the last thing you need to do!
What is it doing?
Does it turn over but not catch?
If it catches what does it do next?
Did you replace starter motor complete with solenoid?
If it does not turn over try removing the Starter Relay and jumper pins 87 and 30...engine should turn over provided fuse 8 (40 A) under the hood is OK and the ground strap grounding the engine to the chassis is clean and tight...battery cables must also be clean and tight and negative lead going to chassis must be clean and tight.
If this jumpering does turn over the engine then swap over Starter Relay and make sure fuse 28 (15 A) under the hood is OK and the Transmission is in Park and the Transfer case is in N. If the engine now does not turn over then jumper the Black/White wire going to the Starter Relay pin 85 to ground somewhere and see if it turns over.
If the engine does turn over but does not start then check if the Auto Shut Down (ASD) relay under the hood is energizing. If not then check fuse 15 (10 A) inside the cabin.
Does your Jeep have the SKIS immobilisor system instaled? If it does have this feature then an amber key symbol with a stripe going through it should briefly light on the cluster when the ignition is turned ON.....you want this light to go out very soon and must not flash at you or stay ON.
That is enough for you to check for now.