[Eguzman0920]

I was having the OP's issue along with my alarm going off with it was locked. dome lights would come on and door ajar would flicker on and off while driving.
Here's what solved the issue for me.
Easy repair. Just basic tools and a couple of hours.

These use a sweeper arm, kind of like a fuel level sensor in a fuel tank, to tell if the door is open or closed.
Over time these arms can wear down a bit or get jostled hard enough to bend the arm, making good contact hard.
The doors use: circuit not grounded = door open
circuit grounded = door closed

-Remove the door panel
-Unplugged everything
-Unbolt door plate and let hang, no need to remove
-Remove plate
-Undo the 3 screws for the latch assembly
-Undo actuator rods for handle and key
-Pull unit out
-Remove screws and open unit up(It is not glued together)
-Remove the arm and bend brushes out slightly
-Reassemble

Hope this helps someone

I was having the OP's issue along with my alarm going off with it was locked. dome lights would come on and door ajar would flicker on and off while driving.
Here's what solved the issue for me.
Easy repair. Just basic tools and a couple of hours.

These use a sweeper arm, kind of like a fuel level sensor in a fuel tank, to tell if the door is open or closed.
Over time these arms can wear down a bit or get jostled hard enough to bend the arm, making good contact hard.
The doors use: circuit not grounded = door open
circuit grounded = door closed

-Remove the door panel
-Unplugged everything
-Unbolt door plate and let hang, no need to remove
-Remove plate
-Undo the 3 screws for the latch assembly
-Undo actuator rods for handle and key
-Pull unit out
-Remove screws and open unit up(It is not glued together)
-Remove the arm and bend brushes out slightly
-Reassemble

Hope this helps someone

Hey man so as I was attempting the fix on the unit, this little round spring came off and I can’t seem to figure out how it goes back in… any idea? Thanks in advance… perhaps maybe a FaceTime or a call. I’d gladly appreciate it.

 

[Georgie Loxley]

Hey guys, I'm having a problem with my 2010 Mazda3 hatchback.

While driving, occasionally the "door ajar" light turns randomly on and off and according to the display, the faulty door is the front passenger door.

My question is where in the door can the problem lie? There is no button on the door that comes into contact with the body so I'm guessing the sensor is part of the entire lock assembly. It happens so randomly that I have to leave the center dome light permanently off as it has turned on in the middle of the night before due to the car suddenly thinking the door is open.

What do you guys think? Any help will be greatly appreciated as it is no longer under warranty so I will have to purchase/install any parts by myself.

Pop the door sail off and check the ground wire linked to where the door locks.

 

[wankelmonkay]

Something to keep in mind, the plating on the contacts is likely nickel or zinc and is a corrosion inhibitor. If that’s worn down you’ll either need to use electrolysis to recoat them or buy a new latch assembly. Otherwise the problem will likely return after a short period of time. I’m familiar because the same problem happens with RX-7 window switches.

 

[jassolb9]

Glad to hear you found the problem,sometimes that type of problem is impossible to locate, and some folks have paid a fortune in labor costs tracking something like this down. Pat.

Any pictures of where was grounding

 

[Eguzman0920]

Something to keep in mind, the plating on the contacts is likely nickel or zinc and is a corrosion inhibitor. If that’s worn down you’ll either need to use electrolysis to recoat them or buy a new latch assembly. Otherwise the problem will likely return after a short period of time. I’m familiar because the same problem happens with RX-7 window switches.

I bought a new latch assembly after a failed attempt at opening the current one, problem is still ongoing

 

[christianac__]

I was having the OP's issue along with my alarm going off with it was locked. dome lights would come on and door ajar would flicker on and off while driving.
Here's what solved the issue for me.
Easy repair. Just basic tools and a couple of hours.

These use a sweeper arm, kind of like a fuel level sensor in a fuel tank, to tell if the door is open or closed.
Over time these arms can wear down a bit or get jostled hard enough to bend the arm, making good contact hard.
The doors use: circuit not grounded = door open
circuit grounded = door closed

-Remove the door panel
-Unplugged everything
-Unbolt door plate and let hang, no need to remove
-Remove plate
-Undo the 3 screws for the latch assembly
-Undo actuator rods for handle and key
-Pull unit out
-Remove screws and open unit up(It is not glued together)
-Remove the arm and bend brushes out slightly
-Reassemble

Hope this helps someone

Do you know what wire the arm would be connected to on that plug?

 

[Tired Antechinus]

Okay, so I'm battling through my problems Door sensor light always on on dash. Manually locking front door just pops back to unlock. Unlock on key fob works but lock doesn't. Have swapped drivers side door lock mechanism, same with passenger side rear and tail gate. Problem still there. Will replace the other two door locks tomorrow(I bought a smashed donor car for many things as I have four of these Mazda 3s crashed I'm trying to fix). If I still have the problem, what am I chasing next?

 

[arhodes79]

Pop the door sail off and check the ground wire linked to where the door locks.

We are having the same issue with our 2012 Mazda3 hatchback. Could you please explain what you mean by "pop the door sail off"? As in, what is a door sail, where is it located and how would one pop it off?

 

[charalampos.ziakos]

Hey man so as I was attempting the fix on the unit, this little round spring came off and I can’t seem to figure out how it goes back in… any idea? Thanks in advance… perhaps maybe a FaceTime or a call. I’d gladly appreciate it. View attachment 291418 View attachment 291419

Hi guys, also the same issue here (spring poped up and cannot reassemble it). Any hints?