2000 jeep wrangler will not start from the key switch, can start the jeep by jumpering the starter, have replaced the key switch, the ignition relay, and the ignition circuit braker.

Sounds like you're starting at the expensive end and working backwards! First, check your battery, make sure it has a good charge. Second step is the starter solenoid. Some designs have external solenoids, some are internal. Third is the starter itself. Once you are sure all that stuff is good, THEN it's time to start looking for the neutral safety switch.

The check engine light is meaningless when the engine is not running.

can you use a jumper wire at the starter to bypass the key ? Jumping the small wire on the starter solenoid with the large wire should make it crank.

Have you checked the neutral safety switch and the starter relay in the power distribution center?

The problem is in your ignition switch. The ignition switch is in the steering column. It is just inside or under the dash. The ignition switch is not sending power to the starter solenoid.

you have an ignition voltage problem or ignition box failure.

have u ck out the ignition switch [not the key & tumblers],, or the neutral safety switch to see if u have power ,,also seen broken wire at solenoid on starter too,,hope it helped,,

Nuetral safty switch, Starter solenoid.
Do you have antitheft?
The ground for the starter relay may be computer controlled. Lee

First, make sure you can turn the engine by hand. If you can't then the starter can't turn it either. Have someone else turn the key and look for the source of the click...may be a relay. Go over the starting circuit with a volt meter. Check for power at the starter main terminal and then with the key turned to "start" check for power at the trigger terminal on the starter. Check battery voltage and check relay operation.
You have a neutral safety switch on the transmission if its an automatic and a clutch switch if it's a stick. Check them as well. Make sure battery grounding on fender and block are also clean and secure.

If there is no power coming IN to the starter relay - the ignition module has failed.
Replace the Ignition.

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The Starter relay is bad.