Rearview mirror has no power

[GabGia]

Hello all, I apologize if this has already been covered, I’m new to the forum.

I just bought a 2015 640i Gran Coupe, and was trying to program the homelink buttons to my garage. After struggling a minute I realized that no lights were ever coming on in the mirror, and the compass is not on either. It looks to me like the mirror is just not getting power.

I checked the fuse diagram found in the trunk fuse box, but I can’t make day or night of what fuse to actually check.

Maybe fuse 8, or 134?

Is anyone familiar with this issue?

Thanks!

[Opie55]

There isn't a compass in the mirror, but you should get some yellow flashing lights when you hold a button. In the fuse box in the trunk side panel there should be a folded up paper fuse diagram tucked along the side of the fuse box. See if you have one.

[GabGia]

I do have it, and I was looking through it yesterday. There’s the little simbol that looks like a house, next to the parking sensor one, and it shows fuses 8 and 134.

Am I reading that correctly?

[GabGia]

Sorry, I thought I attached the photo, but clearly didn't. Also apparently don't know how to show the photo in with the text.

[Qsilver7]

Gotta ask…are you trying to program the HOMELINK buttons without pressing the START button? The car must be powered on to program or use the HOMELINK buttons…it’s a safety precaution.

If the HOMELINK buttons were always powered, then all it would take for a thief to gain access to your home if the car is parked in the driveway or street in front of your home…would be to bust a window, then press one of the buttons.

Thus the car has to be powered before the buttons will work.

The HOMELINK (garage door opener) is under the control of the JBE module (in the f06)…which is powered by fuse #8 you see listed. F134 is powering the PDC features. Again, make sure the car is powered on if you are trying to program the buttons.

[GabGia]

The car was on as I was trying to program it, the videos I watched on how to do the programming said it needed to be so.

Thanks for the diagram! I will check fuse 8, hopefully I find a burnt fuse and the solution is that simple!

Side note, when I lock the car, the red light for the alarm does blink, but I assumed since it is part of the security circuit, it would be powered independently to the rest of the mirror functions. Does that sound about right?

[Qsilver7]

Originally Posted by GabGia

Side note, when I lock the car, the red light for the alarm does blink, but I assumed since it is part of the security circuit, it would be powered independently to the rest of the mirror functions. Does that sound about right?

It’s a bit more complex than that. In fact, the wiring diagram is too large to get a screen shot. The LED is connected to the roof function center module, but is also connected to the CAS module (which is a major module for lock/unlock function)…as well as the JBE & Footwell module.

[SixPost]

Another possibility. You really have to press the homelink buttons firmly to get them to work. Takes much more pressure than any other vehicle I've ever owned. Yellow light blinks above the buttons when you've pressed hard enough, assuming you have power.

[GabGia]

Well I failed miserably at getting to fuse 8 inside the glove box with my non-small child hands…

Ordered a set of footlong needle nose pliers to try and get to it. Fingers crossed that’ll help me get it.

[GabGia]

Holy moly, SixPost, you were right… if I press the buttons ungodly hard, the light comes on… I mean, absolutely unreasonably hard… but there are the lights. I’ll try programming it here in a bit.

[GabGia]

Well I’ll be a freaking monkey’s uncle, it’s programmed and working… nobody in the videos mentioned you needed to press hard enough hard enough that you crack your knuckles doing so.

Thank you everybody.

[Qsilver7]

[Frupal]

Glad to have read this! I always thought that the BMW put out a weak signal. My Benz opens the garage with barely a touch. But now, I press the living hell out of the BMW button and it opens right up! My knuckle does crack occasionally! LoL! Thanks!

[Qsilver7]

I grasp the left side of the mirror and press the buttons with my thumb.