Need help on my power windows that are broke!

[jbres]

Need help from some power window experts. My truck is 2007 GMC 2500 CC SLE Classic. The 2 rear power windows wont roll down any way I try it. They wont go down by the buttons in the rear, nor the main button up by the drivers seat. The front windows are working fine.
I thought maybe its a fuse, but the only fuse I could find for it was a large gray fuse, and it wasn't the type I can visually check to see if its blown.
Anybody have a clue on this?
And the windows were in good perfect working order just last week, no signs the motor was going bad.(truck itself only has 78k on it)

[BurbMan]

jbres, the info I could find talked about the fuses protecting right side and left side as you noted, not front and rear. So it would seem for both rears to stop working would indicate two fuses but then the fronts shouldn't be working either.

I mentioned power seats because that's also tied into one of those master circuits and would indicate a blown fuse.

I would check every fuse that you can to rule out a blown fuse. Once you;re sure there are no blown fuses, then next is the window switch panel on the driver's door. You can try pulling the switch panel and jumping the connectors to see if you can get the windows to activate.

If you can rule out the switches then next is the BCM as peeps suggested, but that's $$$ to replace. Since both windows quit at the same time, it's unlikely there is a wiring issue to the window motors or switches.

[jbres]

Thanks everyone for the replies so far.
Both rear windows just suddenly stopped working all together.
Burbman-thanks for the detailed message. Truck does not have power seats at all, if that helps.
I was looking over the fuses in my owners manual, and it appears the ones you talked about MBEC AND LBEC are separate, one for drivers and one for passengers. Is it possible that I could blow each of these separate at the same time to cause both rear windows to not work? Otherwise I was looking through the different fuse descriptions and the only others it seems it could be are CB RT DOOR AND CB LT DRS. both are rear power window fuses, but again could they both blow at once?
Thanks a lot for the advice so far!

[monkey44]

Some older trucks had a latch, some an electronic switch ... it should tell him in the owners manual.

All (I think) have child door locks, some have child window locks.

[mich800]

monkey44 wrote:
I'm betting it's the child-lock feature ... open the door, look in the panel for a small lever -- it keeps the kids from opening the rear windows and falling out while driving.

It could also be an electronic lock somewhere -- read your manual under child-lock..

The child locks on every vehicle I have driven/owned only prevented the door from opening not the window. The window was controlled at the master switch at the drivers door. Is this a GM feature?

[larry_barnhart]

On our 05 chev the windows can be locked if I hit the switch on the arm rest.

chevman

[monkey44]

I'm betting it's the child-lock feature ... open the door, look in the panel for a small lever -- it keeps the kids from opening the rear windows and falling out while driving.

It could also be an electronic lock somewhere -- read your manual under child-lock..

[BurbMan]

jbres, are the power seat controls working? If not it's almost certainly a fuse.

The 3 fuse panels are:
1. Under the hood.
2. Under the dash, to the left of the steering column.
3. On the left side of the dash. Open the driver's door and look for the access cover on the side of the dash.

Look in your owner's manual for the applicable fuses and circuit breakers. There are also maxi-fuses under the hood labeled MBEC and LBEC that protect groups of components and one of those could be blown.

To test a fuse, get a multimeter and set it to ohms (resistence) to check for for continuity. Pull the fuse and put the two leads from the meter on the two fuse prongs, one lead on each prong. If the fuse is good, Ohms of resistence will go to zero on the meter, indicating that there is continuity inside the fuse. If the fuse is bad, there will be no change on the meter.

If you can't find any bad fuses, the next place to look is the switch panel on the driver's side door, that module may have gone bad. Peeps, not sure why you start with the BCM, I like to start with the cheap components first and work my way up the $ food chain....since the windows stopped working suddenly and as a pair, I would suspect a fuse.

[jbardram]

jbres wrote:
I haven't been in the truck using the windows at all during the snow...The back two just wont go up or down in any way, shape, or form. Where is the 3rd fuse panel located? I know where the one is driver side panel side dash, and obviously one under hood. I cant seem to find the 3rd.
Also, how do you test the big fuse type since you can just visually examine them

You can swap the relay with another to see if the suspect one is bad...

[jbardram]

Had to replace the actual window switches on my crew cab...both rear doors but at different times. Fortunately an easy and relatively cheap fix. I guess water worked its way in over the years.

[jbres]

I haven't been in the truck using the windows at all during the snow...The back two just wont go up or down in any way, shape, or form. Where is the 3rd fuse panel located? I know where the one is driver side panel side dash, and obviously one under hood. I cant seem to find the 3rd.
Also, how do you test the big fuse type since you can just visually examine them

[2003silverado]

My vote is for fuse too. Do you have kids that ride back there often? I see you are in Ohio where it has been quite frigid lately. Might be possible the window was froze shut and someone held the down button for too long stalling the motor and blew a fuse.

[IAMICHABOD]

Had this happen to my 05 Yukon. It was a fuse,there are 3 fuse panels on mine and I had to go to the owners manual to find them all. Some under the dash and the big one under the hood. As I remember it was a large Grey one under the hood.

It has been a while but as I remember the locks wont work on the front doors too. They seem to be in series so you have to check them all.

[Turtle_n_Peeps]

My WAG:

The BCM went out. That would be the first thing I would go after.

[coolmom42]

It seems unlikely that both windows would get broken wires at the same time.

Get a multi-meter and check that fuse. Seems to me it almost has to be something electrical. Possibly if someone tried to roll one down with ice on it, the fuse blew.

Also... google the year/model of truck plus "rear windows won't roll down". It's amazing how much you can find out that way.