central locking question

[gareth]

my central locking is being temperental and keeps blowing the thermal fuse. what would cause this?

a bit of background...
the central locking had always worked faultlessly until at santa pod where it packed up! upon inspection i found the central locking control box was positioned upside down and had filled with water! (my fault i reckon as i'd had it out while changing the doors a week previously....). a few of the resistors on the end had corroded so i replaced these, cleaned it off and dried it all out. when i refitted it, all was fine again but a day or so later it stopped working. it now just blows that thermal fuse after a day or so every time.

is this likely to be a problem with the control unit itself or something else? the wiring and solenoids on the new doors were all transferred from the old ones and was all in perfect condition.

[A1BMW325iSport]

if the wiring is good like you say, its most likely the control unit mate

[gareth]

righto, i've got another one on the way but thought i'd best check in case i burn that out!

[Brianmoooore]

Never experienced it myself, but a flooded lock ECu sometimes fries all the lock motors. Fitting a working ECU to these would probably trip the thermal fuse.
Remove the ECU completely and identify the brown (earth) wire and the 12v+ (red/black) wire in the socket.
Now find the white wire and the blue wire.
Take two short pieces of wire, link brown to white, and then just touch red/black to blue. This should lock all the locks. Check they all have, then link brown to blue, and just touch red/black to white. They should all unlock.

[gareth]

cheers brian, i'll try that if and when the rain stops.

when the thermal fuse is connected, the central locking 'works' fine, though i don't know how hot that control box runs?

[Brianmoooore]

Control box only provides a brief pulse to move the motors one way or the other. Rest of the time it draws almost zero current, so shouldn't generate any heat at all.

[gareth]

righto, i'll check that. iirc the fuesable link was running slightly warm so that's quite a lot of current to heat that thing up!

i'll try the new one that is on the way to see if that helps as this could be down to the damage mine had recieved.