Hopefully this is the right section for this question. I have an '07 JK X, and replaced the battery yesterday. Recently, the engine has been hesitating to start and didn't start at all this week--I figured it might be the battery. With a new battery in, the engine starts fine with the positive and negative cables connected AND with the green fusable link disconnected (with a battery icon visible on the dash). When the green fusable link is connected to the positive terminal, the engine doesn't even attempt to start. I'm not very experienced mechanically, but I'm trying to fix this issue without taking the Jeep into a dealership. As far as I can tell, it sounds to me like the alternator might be bad, and/or there might be a blown fuse that connects to the fusable link. I'll have access to a multimeter and an OBD cable on Thursday, but can't check any voltage between now and then. I'm curious if anyone here has experienced this before, or has enough knowledge to confirm my suspicions or point me in a new direction.

 

I think you are on the right track, but it's surprising that the fuse link to the alternator didn't blow given it won't start when connected. The only thing bad that connecting the green fuse link can do is draw current, and lower the battery voltage.

I'd start by measuring battery voltage, prepare for a big arc, then touch the green fuse link to +, and watch the voltage. A DC clap-on ammeter would be handy as well. An OBD scanner may reveal some DTC's. Wondering if there's some related logic in the PCM or TIPM to keep it from starting with a certain failure like this??? If there are DTC's, post them up. Note that it takes a higher end scanner (see link below) to read anything beyond the standard codes in the PCM -- See link in sig below.

Stay in touch, interested in what you find out.

 

I would agree with MrT and say the alternator is suspect. Perhaps the original battery was fine. Did you see an arc when touching the fuse link to the terminal or did you have the ground disconnected.