Door locks don’t work w key fob

[Origowner]

Both fobs suddenly stopped working at the same time but the interior door lock/unlock button works and the key works. None of the door actuators make any sound when trying key fobs and none of the doors lock/unlock with the fobs. I’ve read a number of posts and have tried the following:
Checked all the fuses
Used brother in law’s vadis(?) to see if any error codes popped up - nothing
Replaced batteries & cleaned fob contacts
Reprogrammed fobs by 1. locking/unlocking w key several times in a row 2. Getting in car, closing doors, used key to put ignition in position I and holding down door button for 15 seconds 3. Getting in car, closing doors, used key to put ignition in position II and holding down door button for 15 seconds
Checked UCM by opening and closing sunroof.
None of this has solved the problem.
The fuel access cover has now stopped working too. Pressing the button does nothing. I checked all fuses again and wire harness connection to fuel cover release button. I’m guessing that at this point I have to take it to a mechanic for troubleshooting. Any suggestions before I spend a ton of $ on a mechanic?
Thank you!

[firstv70volvo]

Is it completely dead, no key fob buttons work at all and it's not an intermittent type problem? I had a problem with my UEM where it wouldn't well on hot days when the car was parked in the sun. There was a part on the receiver board inside the UEM (rear vew mirror) that stop working well when hot.
Does the homelink work, the upper dome lights?


Here's photo of the UEM receiver board, removed in this photo, it's a vertically mounted board on the main UEM electronics board. I was able to replaced this board with one off a salvage part and no progamming was required. Not an easy job but it did work.

[Origowner]

Thanks for the response! The fobs don’t work at all. Tried when car cold inside and when warm inside. The upper dome lights work. Don’t know what home link is or how to check it.

[firstv70volvo]

Thanks for the response! The fobs don’t work at all. Tried when car cold inside and when warm inside. The upper dome lights work. Don’t know what home link is or how to check it.

Homelink is jthe wireless garage door opener option buttons in the sun visor. It sounds like the UEM is mostly functional so a reset isn't the problem. Based on the symptoms I think it might be a problem with the receiver electronics in the UEM. I remember taking my car into the Volvo dealership when my key fobs weren't working and they couldn't even determine which module was causing the problem, they said it may be the UEM or maybe the CEM and quoted some outrageous cost to repair. When I noticed it was a heat related problem I took a heat gun and found out it was the UEM electronics, I could heat it up and reproduce the problem.
Your problem sounds more like a hard device component failure in the UEM receiver circuit. You could take the rear mirror apart and check to see if there's anything obvious, like a burnt component or bad solder joints but this might be a long shot. The problem is the UEM is not cheap to replace and programming is needed when a new one is installed. In my case I was able to replace just the receiver board and it actually worked but I can't say if this works in every case and it was difficult to remove and install small vertical circuit board, little connection clips join the two boards.

[Vova585]

Totally agreed with firstv70.
UEM would be my first suspect. If your mirror shows signs of "leakage" (dull, anti dimming is not working, black spots) it is most likely fluid leaked on electronics and it is toast. I would vote to remove UEM and find part number. Buy used one with the same number. Send to xemodex for service(they will transfer info from old to new) for $300 and hopefully you are in business. You will pay dealer at least $200 for 1 hour of diagnostic time, so worth the risk IMHO.