Yea I have U73 not U77.

 

fix for 2004 monte carlo rear window defrosters.

on the INSIDE of the passenger side dash fuse block there are two circuit breakers. one for power seats, the other is for the rear defroster. the fuse block cover has a label that clearly shows which is which. if you open the glove box door and let the glove box down you'll see a bolt that holds the fuse block in place. remove it, and the fuse block will come out. it's not easy, but it can be maneuvered out. the circuit breaker can be replaced. on my car, the melted circuit breaker had done damage to the fuse block as well. i did a repair to the block using epoxy, soldered a pair of 12ga wires into the sockets that once held the circuit breaker and hung a 30amp circuit breaker on the OUTSIDE of the fuse block under the dash end panel. i don't know why this circuit gets so hot! within minutes of turning on the rear window defroster the circuit breaker is very hot to the touch, as is the wiring. if the circuit breaker melts down again it will be a lot easier to replace with it on the outside of the fuse block.

can anyone explain wire this circuit gets so hot?

 

I just did a write up with Duke's information (using my wife's '05 Impala for pictures).
You can find it here:
https://montecarloforum.com/forum/si...33/#post401342

I hope to fix my Monte's defroster in the spring when I uncover it.

 

I just spent the morning tearing apart my 01' SS looking for that connector. After seeing your schematic, I ran a test light on the relay. It would appear that I am not getting power from the BCM yet the defrosters in the mirrors are working. Any ideas?

 

If it is like mine, it wasn't hard to diagnose!

 

did you check the circuit breaker found on the BACK of the passenger side fuse panel? If not, use the link in post #33, tells you (with pics) how to get at it (using my wife's Impala, some process for a Monte).