BCU unit
 

i have a 2005 mazda 3 got a faulty BCU UNIT can anyony give a solution/where i can purchase a new one?

So what is the BCU unit anyhow? that's a new acronym for me.

oh sorry....the bcu unit is a factory installed module which controls the locking and unlocking of the vehicle with the factory remote.........i think it's some sought of security system

The keyless control module has no specified acronym (like BCU or RKE - remote keyless entry) in the workshop manual or wiring diagram... so you may not be able to find it using that term. But for your information, it's a small module - just a couple of pins on the connector, and it's located above the headliner near the interior light above the mirror.
This wireless reciever is the same as the tire pressure monitoring system (TPMS).