Hi all 1st post here

Anyway,

I'm pulling my hair out on this one. I have a 2004 Impala, just plain jain nothing fancy. My rear defroster doesnt work. I gotprint out (see below) and it says there should be 30amp breaker on passenger side. owners manuel says same thing. But when I look all I see is connector block for that fuse block?

I replaced the relay and I get 12v all time from engine compartment. But when I measure at plug ins in rear window I get nothing. Yes I tried going to ground and across each other and any possible combo (I have extensive electronics back ground, automotive, mechanical, well.... it's getting better)



Underneath grey cover on right side looks like connectors for wires to fuse box. I tried to take it off but I unscrewed that screw and it still didnt come all way off and I was afraid to pull to hard and break something. Or should I?
Like I mentioned in aboveI have no idea where that breaker is.

I'm wanting to see if I'm getting voltage to breaker. then go from there.....

Also what is 'radio antennna module (on upper left portion of left "C" Piller)'? I see this and it has printed circuit board and 3 wires going into it. See wire diagram below.


click on pic for larger view. after you click on it, lower right corner of pic it says 'full view'. click that



Thanks for any help

 

If you check the green wire at the antenna module for power when the defogger is on it should give you an idea if power is being delivered to the rear. If there is power back there, and as long as your ground is good, then you will be looking at a new antenna module.
As far as i can tell, the circuit breaker is underneath that grey cover on the right side of the fuse box. There is a 30amp power seat breaker near the center, and a 30 amp breaker for the rear wiondow defogger towards the bottom.

The radio's antenna is a grid on the rear window. The signal need to be amplified so the radio can pick up station like it would with a fixed mast antenna. Hence the reason for the antenna module. Why they integrated the defogger circuit with it is beyond me

 

I found out where breaker should go but 1st...

Like I mentioned above under grey cover is terminal block:



Then I was able to get it all the way off to see what's nderneath:




But I did find where breaker should be on back side. I had to take out glove box. But there was only one breaker! The one for the power seats. I see contacts for other stuff. I tried to test for voltage but I need better adaptor. My leads wouldnt fit in and I tried wire but I dont think I'm getting good contact. None of the numbers matched up on schematic to panel either. There are like 5 contacts but 3 are in a row and you can't use 2 because of the power seat breaker.

So I go to local autoparts store and they show nothing for breaker [X(]

But, my neighbor has an 04 Impala and I'm going to see if they will let me look at theirs.

Also on the radio board in back there are 3 wires going to it and all same color, black. Must be junction in rear piller but I'lll worry about that later if need be.

 

Have you checked fro power on the green wire at the antenna module?

Also, you said you had a plain jane model...do you even have power seats?

 

I went and looked at my nieghbors and saw where there breaker is. Mine is missing! It should be lower right corner when looking at it from under dash. It's hidden my metal bracket andI didnt see the contacts as it's a PITA to get to. But I'll get it, I have an idea

Like I mentioned above for the antenna module there is no green wire as there are 3 wires attached to it and all colored black. I'm not sure what other 2 are unless I get radio schematic. But I dont need to yet since I have no circuit breaker.

Yes I have plain jane model but I do have power seats and I took that breaker out and seats didnt work so i know what it does..

 

sounds like you have it narrowed down then. CB's are fairly cheap to buy, I think around $15-20

 

circuit breaker is behind right side fuse bx behind glove box toward right you see one fuse which is for power seat just below to right is a hidden fuse for rear defroster there is one 10 mm bolt top toward seats to remove and a plastic clip to release fuse bx remove fuse bx from front side change 30 amp circiut breaker

 

I know I am behind a couple of years on this post but if someone else should find they have the same issue here was my story. I am also doing a short little YouTube video.
I am diagnosing the same issue on my wife's 04 Impala, I will skip the continuities and the voltage testing and the antenna module I replaced and get right to what I found. When I pulled the glove compartment I found a 10 millimeter Bolt that I removed then released the tabs and pulled the whole fuse box out when I check a circuit breaker that way, it was good but I found was it an overheated and melted the plastic and screwed up the connection inside the circuit breaker fuse box. I put a slight Bend out and back on that leg of the circuit breaker, and put it back in. That regained continuity to that circuit or power to that circuit but I think I need to replace the whole dang box if it happens again.