Electrical Problem

[AMPlibby06]

So my radio wasn't working last week (very long story) so I decided to replace it. Went to replace it, two wires crossed, blew the radio fuse. Standard stuff, so I went to replace the radio fuse and I started checking for blown ones to diagnose why my radio wasn't working (because the new one wouldn't work either). In doing so, I pulled the large white double fuse holder because I read that one of the fuses controlled the radio. It said BCM/radio/some other stuff. I pulled it, it wasn't blown, so I replaced it.

Here's the problem:
I'm getting no constant power when the KJ is off. Keyless entry, door locks, any lights, etc. don't work when the KJ is off. Any ideas of what may have happened? I don't think the little wire crossing of the radio did it, but I could definitely be wrong. Is the BCM just thrown off? Any ideas? If I can't come up with something, it's going to the stealership to figure out what happened.

Thanks in advance!!

Alex

 

[JeepJeepster]

Dont let the dealer know that you crossed some wires if youre under warranty. Do you think something was wrong with the old cd player or do you think its related to the current issue? Did the key less entry work before you crossed the wires?

Maybe you know this now but ALWAYS unhook the battery when doing electrical work.

 

[AMPlibby06]

Yeah I should have disconnected it, but I'm at school in vermont without a socket wrench. I was dealing with harnesses, but my new cd player didn't come with a harness so I had to splice. Everything worked before the wires crossed EXCEPT for the radio. Since neither radio works (including the brand new one) i think it's safe to assume that it was an electrical problem. I'm not under warranty, so I'll just have them take a look, if nobody here knows what I should do.

 

[JeepJeepster]

Well, hopefully it was just a bad radio before and doesnt have anything to do with the current problem. If you have a volt meter check to see if youre getting power to the cd player.

I hate to say it but the only thing that really controls the key less entry, lights, and door locks and all of that is the BCM.. Which is the computer for everything inside of the Jeep. Fuses are not really for keeping things from getting damaged from shorts but rather to keep wires from getting over loaded and catching fire.

 

[AMPlibby06]

but if the BCM went, then why would that all work when the car is on?

 

[JeepJeepster]

The BCM controls the grounds for everything. When it wants to turn something on and off it will turn that ground on and off(as far as I know its the grounds and not the + side, odd I thought, not 100% sure on that though).

Anyway, its kinda like the over head lights. They will come on when you open the door but they will also come on when you push them. This means they have a ground to turn them on when the door opens and another ground to turn them on when you push them. Youve lost the side that gives everything power when the Jeep is off. Make 100% sure that you do not simply have a fuse blown. Check them all if you need to.

Im just bringing all of this out of my head, not an electritian or anything of that sort. Just trying to help based on what I 'think' I know.

 

[kb0nly]

He's right, the BCM switches the grounds to everything, pulling too much current through the BCM is usually how they get fried, thats why there is the warnings about adding to many lights to the interior lighting circuit or anything that the BCM controls.

You may have very well fried something in the BCM and thats just how it acts in its damaged state. Before you write off the BCM though i would get a test light or voltmeter and check every fuse in the interior and underhood fuse panels. Eliminate all other possibilities first. Once you have eliminated all that then all it could be is the BCM.

Note that some fuses are only powered with the key on, and some are powered with it on or off. So if nothing else to make it easier though more time consuming pull every fuse one by one and visually inspect and even test with a good meter on the continuity setting to be sure. Considering the price of a BCM i would eliminate all those possibilities first.