INADV Power Bus keeps blowing...

[LittleHoov]

I thought Id ask if anyone else has ever had this problem.

This fuse keeps blowing repeatedly, I put a new fuse in and it worked for a day or two, then blew again, and now just blows basically as soon as I start the car after replacing said fuse.

This fuse provides power to the radio, windows, and interior lamps. So its kind of a pain to do without sometimes.

I did find one post that mentioned in passing a certain wire on the BCM might be bad. It was not on this forum.

Ill be pulling my radio out to check for bad wiring as thats the only thing I can think of at the moment, though the radio has been working fine for at least 3-4 years.

Any other ideas?

[krivasauto]

Originally Posted by LittleHoov

I thought Id ask if anyone else has ever had this problem.

This fuse keeps blowing repeatedly, I put a new fuse in and it worked for a day or two, then blew again, and now just blows basically as soon as I start the car after replacing said fuse.

This fuse provides power to the radio, windows, and interior lamps. So its kind of a pain to do without sometimes.

I did find one post that mentioned in passing a certain wire on the BCM might be bad. It was not on this forum.

Ill be pulling my radio out to check for bad wiring as thats the only thing I can think of at the moment, though the radio has been working fine for at least 3-4 years.

Any other ideas?

Had anything big in the trunk? Maybe knocked into the trunk light?

[LittleHoov]

Hmmm as a matter fact I did shove a giant metal cot in the trunk the other day just before this started happening...

Ill have to check it out...

Its only blown "on the fly" once, and that was after I hit an enormous bump...other than that its seriously like it blows just sitting there.

For example, yesterday when I went to work everything was working fine, I did come out to the car a couple times, open the door and shut it, and then when I left to come home last night everything was dead.

Ill check out the trunk though for sure...I had to cram that baby in there, so mightve knocked something around.

[LittleHoov]

Well I didnt see any immediate problems with the trunk light wiring, I went ahead and pulled the bulb out too, just for kicks, a new fuse held for about a day.

Same thing again, I was rockin' out when I pulled into to work, everything was working fine. Came out 9 hours later and opened the door to find no interior lights, no radio, no power windows....sure makes for a quiet ride home.

The plot thickens I guess..

[LittleHoov]

Well finally got around to messing with this thing. Im relatively certain I found the problem.

I spent a lot of time perusing FSM's and such trying to find out different possibilities. Public thanks to krivasauto for his assistance in that!

I decided to start by pulling the radio, I had installed it several years ago, and figured my install might have developed a problem or two over the years.

I began looking through wires and was greeted by a half-taped, half-bare orange wire coming out of my aftermarket harness, it was...*drumroll* the illumination wire, which I had never hooked up because I knew the illumination did not work for my particular radio, but for some reason I had only bothered to tape the bare end of this wire. Upon further inspection, the same orange wire was coming out of the connector itself where it snaps to the factory wiring....Im thinking one or the other of these 2 was causing it to short out the illumination circuit, which is basically what the IDADV POWER BUS is supposed to control.

Why it also shuts down all those other circuits when it blows I still am not really sure, I think either the power bus circuit or the bcm itself acts as a signal to switch on a relay elsewhere that powers all those things.

This theory as the problem sounds great on paper....but time will tell.

[pfofit]

You're on the right track.
The inadv fuse supplies two circuits, the contacts of a relay in the bcm to control the interior lamps and the RAP (Retained Accessory Power) relay coil.

1.The bcm relay contact puts 12 volts on one side of the interior lights when the BCM decides to activate the coil either when you lift the door handle or turn on the dome light switch.

The other side of the lamps (excluding the mirror lights, they are grounded directly) are then connected to ground though a transistor in the BCM. That's how the dimming is controlled. However the rear view mirror lights can also be grounded directly by the switches on the mirror.

The controlled interior lamps are the trunk, glove box and its switch, radio, the under dash near the feet lamps, the light around the key switch, the visor and rear view mirror lights and the reading lamps in the back seat. It also supplies the cruise control switches and other steering wheel stuff if you got them.


1. The other path is direct to one side of the coil of the RAP relay. It is not activated until after the key has been turned in the ignition and the BCM then grounds the other side of the coil, then the relay contact supplies the windows radio etc. from the IGN 2, 50 AMP fuse. The RAP relay contact feeds those high current devices like radio and windows not the 15A inadvfuse. The BCM leaves these gizmos active after you have turned off the car and/or removed the key until you open the door or after 20 minutes.
If you lose the inadv fuse that contols the interior lamps then the RAP relay coil loses its 12V source as well which kills you other stuff.

cheers

[LittleHoov]

Thanks for the explanation, I figured it was something like that.

I looked at all the wiring diagrams, but all the symbols and abbreviations, and squiggly lines and such just look like gibberish to me.

I need to really apply myself sometime and learn how to read one of those things....

Im hoping I found the problem, and Im glad it was the radio, my next course of action was going to be to run my own wiring straight to the bcm where that power bus circuit comes in....from the sound of it, I still wouldve had problems because the short was on the power output, not the input side...so Im glad I was able to keep all factory wiring intact.