04 bmw x3 no power to door switch

Hey what's going on guys. I have this 04 bmw x3 with no power to the window switch. I checked the 7.5 amp fuse in the power distribution box and it was blown. Put a new one and still no power to switch. Go back to the fuse with my multimeter to a known good ground and check each pin on fuse and 0 volts on both pins. I'm thinking fuse blew again. Pop fuse out and it's good. Still known good ground and touch the contact inside the fuse box with fuse out and one contact has the 12 volts and the other has 1.2. This is where I stop and I ask for help from u guys. My thoughts is maybe a solder joint inside the box is fried. The thing is that when I put the fuse slightly in i can get the 12 volts to the switch but when I put the fuse in all the was i lose all power. I've never encountered this but to make a call on the fuse box on This bmw is pretty pricey I think. Now this lady has been dealing with this issue for some time now and takes it to a shop where when she accidently puts the window down they can bring it back up. Now I don't know if they grounded the main feed or sent power to the wrong wire and blew the fuse and messed up the box in the process. I don't know. If u guys have any ideas or approach I can take to verify if it is the box that for messed up inside. This fuse box is on the passenger side In the glove box so not a one two three thing to get down I think. Pole71 helped me out alot with this bmw and he thinks it's the fuse box too. But if anybody encountered this and advice I greatly appreciate. Just wanna get ready for tomorrow when she does comes in

Hey Jay! For reference, here's the link to the thread you're referring to:

www.scannerdanner.com/forum/off-topic-se...ms.html?limitstart=0

Looking at the diagram, I have a couple questions. One, I don't see that the 7.5A fuse in question goes to the drivers window switch? It could be that this same 7.5A fuse DOES provide power to the drivers window switch, and just isn't show on that diagram. Anyway, mostly wanting to make sure that there's a connection between the fuse and the readings you're taking at the switch.

Second, do I understand correctly that the window goes down, but won't go back up? :huh: Wondering if a calibration issue is at work. If you supply 12V through a fuse jumper wire to the other fuse terminal (the one that goes to the motors), does the window go back up correctly? This would make me feel a ton better about making the fuse box call. :lol:

Yeah Tyler on the alldata wiring diagram the 7.5 amp fuse is the feed to all the door switched. Pole71 pulled a wiring diagram for me because the alldata diagram was very difficult to really read on This model. Will attach it on the next post. But yeah like in the post the shop or wherever she brings it to can bring the motor I'm guessing by supplying power to the motor. She has been dealing with this for some time now. So I showed the boss that day was Thursday what I'd seened. She is coming back tomorrow because she didn't have time to leave the car that day. Now I didn't send any power that day because I couldn't understand the diagram honestly until pole71 got one for me from shopkeypro then I can dissect that one. But I'm not one if I don't know where wires are going then I'm not going to start power every wire. Lol. But yeah manually u can send direct power and the window does go up from she told me. But in the post I mentioned that I don't know if these guys she brings it too sent or grounded the wrong wire and fried the fuse box itself. I will have to let them know that if we do make the fuse box call that we are fixing one problem. Now that may or may not fix the window issue but I can't continue until I have full power to the switch. Ur thoughts tyler.

Yeah, that diagram shows what I mean. That 7.5A fuse doesn't go to the switches, but to the motors themselves. Rather, I suspect they're powering the Hall Effect sensors in the motors. The drivers door switch just sends a LIN message to the General Module Control Unit to tell it to roll the drivers window down. You know the LIN network is good, and that the load wires going to the motor are good.

I don't think that someone getting aggressive with a Power Probe would have caused the fuse box issue, as that circuit is supposed to have power anyway. Someone could have grounded it? But that would just pop the fuse. Someone definitely could have taken out the driver in the GMCU with a PP, though.

For reference, do the other windows have the same behavior?

But tyler why do u think the fuse box pins one has 12 and the other has 1.2 volts. Why doesn't the other pin have 12 volts. I don't know understand that. Please explain because I am really breaking my head about it as to how to check the cause. Yeah if the power grounded the power supply that would pop the fuse but couldn't it have piped one of the joints In the box. Have u ever encountered in making a fuse box call other than corrosion on it. And where would this gmcu be at?

I don't know for certain, but I'd suspect that the 1.2V you're seeing is getting fed back into that circuit by another component. The dotted line coming off the 7.5A fuse is Mitchell indicating that circuit goes to other places besides just the window motors. A power distribution diagram would be the thing to check to see what else that fuse feeds.

The box could definitely have an internal fault, no doubt. I've replaced boxes on GMs before due to pin fitment issues, but that's it.