Posted by Simon Forsey on August 1, 2012, 10:39 am
Year of Manufacture *: 2002
Hi
This Smart car has a fault with the central locking.
When you press the lock button the doors do not lock and the hazard lights will flash until the battery is flat. The fule filer cap will cycle open and closed, also non stop.
The scan codes are
B1052 recieved radio remote control key code is outside detection range B1111 unlocking operation failed due to short cut B1112 central locking key button
I have checked the door locks, unplugging them in case they are faulty. I have also unpluged the fuel filler cap motor.
The central control ECU [BCM] is clicking away internally. I have checked the lives and grounds to the unit and they are ok. I have also checked the internal lock switch.
I am starting to suspect the N10 central control unit. I understand that they have to be recoded, but can a second hand unit be coded or does it have to be new.
I have had 2 of these now where the fault has been the key itself but the damage that it has caused has been all of the locking motors burning out. These were early models using a ZEE unit instead of a SAM. If there is a spare key try that to see if the hazzards still flash the same way. I found that they don't. Next remove a door skin to get to a door lock motor and put a bulb in circuit to simulate the disconnected motor. Using the suspect key this showed that power was constantly supplied to the lock motors, burning all of them out. A good key will show the power is only supplied momentarily.
I was trying to get my head around how all of the motors including the rear hatch release were damaged but it turns out the first customer had pressed every button on the key trying to get the lights to stop. I found that the key sends a signal that tells the car to 'lock (or unlock) and then stop trying to unlock in x amount of seconds' but instead a bad key only sends the 'lock (or unlock)' signal only, as it is a corrupted message, and the car doesn't know to stop operating the power to the locks or flashing the hazzards. I hope that makes sense. If it proves to be the same fault as I have seen then makes sure you destroy the circuit board inside the bad key so there is no chance of it being used again. If you dont then all of the new locking motors that you have fitted will be damaged on the first press of the key button. I learned this years back when I saw quite a few early smarts. Don't think that there is a cheaper fix by purchasing a boot pop solenoid to replace the fuel cap lock either because that doesn't work. Fuel cap motor comes with the bracket and locking rod but looks identical to the rear hatch one. It is not and is internally different. They also give a nasty pinch when the skin at the side of your finger gets trapped in there so work carefully.
I had this problem a couple of years ago. In my case it was the SAM module. I fitted new door/fuel cap motors and took the car to Mercedes to code in the SAM unit with C/L fuse removed, from memory. Shaun.