Alright, I take it all back - at least most if it where the JK is concenred.

Went out and started my '11 JK, then pulled the negative battery cable. It did not shut down instantly like it would with no alternator output, but it did shut down afer a couple seconds. This was a computer controlled shutdown. Apparently the system detects the lack of a battery and shuts itself down.

Hard to prove, but I suspect that without a good alternator it would have shut down instantly instead of waiting for a command from the computer.

I have 4 other rides in my driveway that would have kept running. So much for another tried-and-true old school method of testing.

When a day goes by that I don't learn something new, just bury me.

 

Thanks for trying that. I didn't have the nerve to do it.
My understanding was that the PCM, which controls the generator, monitors the battery voltage, and upon detecting no voltage, it would shut off the generator field, killing the remaining power source.

 

Not sure where this leaves the OP, but probably still a good idea to get the charging system checked because there had been a dead battery without any explanation.

Not sure how I feel about this Jeep doing all my thinking, but the only other choice would have been a Wrangler much too old for our needs.

 

Where it leaves the OP is, now he knows what we have discussed is not a valid test for the JK.

 

I'd still like to try it sometime with a JK that has a known dead alternator. If the engine stops instantly rather than taking a couple seconds, it could still be a useful field test. The delay was easy to detect; you wouldn't need a stopwatch.

 

Frankly, I think he blew a fuse or left a cable off the battery. The relay making a weird noise sounds like it's not getting a good ground.

OP, can you take a picture of the battery itself with the wires/cables attached?

EDIT: I think he got it fixed. Except for the rock light issue. But at least it's now isolated.

 

Wow! I didn't know that about the JK's either, that's the way I used to check the alternators in the past too. I guess even the Wranglers are not immune to "modern technology"

It is good to know though, probably saved me from changing out a good alternator some time in the future

 

Ok guys thanks for all the posts. Here is what I have to say:

1. I'm not a he. I'm a she

2. I took my Jeep to autozone and had the alternator checked and the guy said everything was fine! I talked to him about the test of taking the negative wiring off the battery and he said that isn't something people do anymore due to the new computer systems in newer cars. He said that test is valid for vehicles made in the 60s and lower and it has potential to blow a bunch of electrical wiring in newer cars (if you reconnect the negative wiring while the Jeep is still running because that is a shit ton of power going in at once)

3. I drove my Jeep to my friend's apartment tonight and we went to workout/run and my Jeep performed fine. Got home and checked the voltage and all is how it should be. I am going to go through the rock light wiring tomorrow or the next day and check for shorts

Thanks again for so much help

 

I just went and looked at your profile:

1. I usually stay away from gender-specific pronouns anyway, but if I had seen your profile first there would have been no doubt!
2. Now that I've seen your profile, I understand how the battery got dead. Two twelves and a kilowatt indeed! Regards to you from a guy who spent half his life doing pro-sound reinforcement.

3. Glad it all worked out. Seems all ya really needed was a battery charger but its hard to tell with text messages.

- Bob

 

I resent that. Can't help it I like my music loud! Haha

But seriously, Bob, thanks for the help. I feel like you were with me from the beginning to the end on this little mishap