Will not lock with key fob or interior button (2016.5 CX-5 Sport)

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2016 CX-5
So my CX five will not lock with the key fob or the button on either front door. The light flashes when I hit the key fob but nothing else happens. The key fob and the door buttons will unlock the doors though. I can manually lock all the doors except rear hatch. Fuse is good. All doors/hood have been checked that they are closed. Any ideas on how I can fix this. 2016.5 Sport
 
Is there another key fob in the vehicle when you are trying to lock it. This would cause what you are experiencing.
 
Is there another key fob in the vehicle when you are trying to lock it. This would cause what you are experiencing.
No other fob. With a fob it usually will lock/unlock real quick. In this case there is nothing happening.
 
No other fob. With a fob it usually will lock/unlock real quick. In this case there is nothing happening.
Are you saying you don’t have a second key fob? If you don’t, you’d better to get one, or it’d be very problematic if you ever lose the key fob, or if you have problems on the current one such as right now.

Try to put a new CR 2025 battery in your key fob and see if it works out for you.
 
Are you saying you don’t have a second key fob? If you don’t, you’d better to get one, or it’d be very problematic if you ever lose the key fob, or if you have problems on the current one such as right now.

Try to put a new CR 2025 battery in your key fob and see if it works out for you.
No. Not saying that at all. Two fobs both unlock the doors. Neither locks the door. Same with the button on the inside of the door. Both driver and pass side button unlock but don’t lock. It’s not the fob because the physical button inside the car does not work either.
 
You say that the doors will not lock with the key fob or any of the door buttons? Including the outside and inside door buttons? Just for shyts and giggles try leaving the second fob in the car when you lock it. Use the driver's inside door button and see what happens.

If I leave a second fob in my car and lock the doors with either the inside door button, the outside door button, or the fob, I get a series of beeps (six I believe). The doors will not lock under these conditions EXCEPT if I use the inside door button. It still beeps but the doors lock and stay that way.
 
It does seem possible that it's something 'mixed up' in the logic. Something isn't allowing the doors to lock.

I might also expect something to beep if a rule didn't allow it to lock, but who knows?
 
You say that the doors will not lock with the key fob or any of the door buttons? Including the outside and inside door buttons? Just for shyts and giggles try leaving the second fob in the car when you lock it. Use the driver's inside door button and see what happens.

If I leave a second fob in my car and lock the doors with either the inside door button, the outside door button, or the fob, I get a series of beeps (six I believe). The doors will not lock under these conditions EXCEPT if I use the inside door button. It still beeps but the doors lock and stay that way.
 
I tried that thanks. Thanks he issue i’m having is that nothing happens except the lights flash when I use the fob. Other then that there is nothing, no noise, no motion. Has to be some sort of electrical issue.
 
The turn signals like they normally would. I think I may have narrowed it down to the BCM. It was really quiet and when I pressed the lock button on the door I could hear a faint click. I traced it back to the area where the BCM is. I unplugged one wire and the locks didn’t work at all. Plugged it back and the unlock was working again as before. Not sure the options on this. Looks easy to replace but the internet seems split over having to take it to dealer afterwards. The large black box is the rear BCM located above fuel door more or less.

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Are you sure the locks are physically and electromechanically able to lock?

There might be a way to trigger a lock with a paper clip or something to prove it.
 
Are you sure the locks are physically and electromechanically able to lock?

There might be a way to trigger a lock with a paper clip or something to prove it.
I can manually lock the doors. It has to be the rear BCM. It’s the only thing that makes sense at this point. The BCM controls the auto locks among other things.
 
You are probably right about the BCM.
I can't hear the click in the rear because the locks make too much noise.

If you can hear it the signal gets that far. Maybe check some schematics to see where the signal goes next?
 
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What about the lock button on the hatch. Have you tried that?
What about setting it for walk away locking and see what happens in that situation.
 
Thanks for everyone’s input. As far as I can tell it was the rear Body Control Module. I found one on eBay from another 2016 CX 5 for $55 and swapped it in today. Locks are now functioning and so far everything else is as well.
Thanks for the update. RBCM usually got damaged when people are not careful replacing the trunk light with LED but the RBCM doesn’t have fuse protection. Mazda revised the circuitry and put in fuse protection to RBCM since 2016 CX-5. Hence it’s rare to see any reports on damaged RBCM on a 2016 CX-5. Of course your problem is different from those from 2015 CX-5 and prior.
 
Nice job. I imagine you probably saved a pretty large chunk of money by getting that fixed on your own instead of at a dealer.
 
Thanks for the update. RBCM usually got damaged when people are not careful replacing the trunk light with LED but the RBCM doesn’t have fuse protection. Mazda revised the circuitry and put in fuse protection to RBCM since 2016 CX-5. Hence it’s rare to see any reports on damaged RBCM on a 2016 CX-5. Of course your problem is different from those from 2015 CX-5 and prior.
Not sure what the cause as I have done nothing that would affect the electrical system. Hopefully it was just a faulty part.
 
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