Help!!!! Starter issues????
 

I have a 2001 JGC 6 cylinder 4.0 liter. I believe I have a Starter problem but am not 100% certain. Nothing happens when I attempt to turn over engine. Battery is good; however, when I jump the starter the engine starts. I removed the starter and took it auto parts store and bench tested and they said it was good. I have replaced the starter relay and the ignition switch. Any ideas? I am going crazy trying to figure out what is wrong. Help me please!!!!! thanks.

up grade your wiring... when I did my starter I had to connect a jumper to the negative and touch the other end to the starter ground to get the initial boost... then I put a four gage ground off the battery to the jeep and a 4 gage power wire going down to the starter... upgrade all your grounds... get rid of any crappy straps...

have you thought about cleaning the battery post connections?

Have you verified voltage at the starter relay when you turn the ignition to 'start'? This requires two people but is an easy check with a voltmeter. Essentially you're looking for power at the signal wire when the key is turned. Once you've verified this, you can move on to checking the power circuit for the starter itself. It's very possible you've got a corroded power or ground cable. Fortunately both are relatively easy to replace, and a good engine ground is always a good thing, keeps the rest of your electricals happy.

X2. Check you battery post and terminals for corrosion and make sure there tight, how was the battery tested? May have it load tested to make sure it don't have a bad cell