Central Locking Deadlocked. Thermal Wire Re-Soldered!!!!!

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MooZ
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Wed Jan 19, 2011 12:53 pm

Hey,

my central locking has recently been playing up, so I took out the ECU relay from the drivers side speaker and realised the thermal cut out (I didn't know it was a Thermal Cut out wire until now) so I simply soldered it up to fix it. Everything was fine for a week or two, until I come back to my car and it's completely deadlocked and won't budge. I manage to get into the car with the key and took another look at the ECU relay, the thermal wire I soldered had melted again, so I tried to fix it again, but to no avail.

I even got a fresh ECU relay unit from a breakers yard and tried that, but still nothing. Brianmooore has advised me I have probably fried my motors, but how can I be 100% sure, before I start buying other parts. He advised me to undo the 2 screws that hold the motor in place and I should be able to pull the pin up and down, which didn't work either.

I want to be able to isolate the problem before I start buying other bits. I remember reading somewhere if you run a 12v current through the brown and blue wire from the ECU box it should either deadlock or undeadlock your doors.. so could I try this before replacing the motors (obviously if it works the motors are ok?)



And would like to think there is some sort of a solution to the thermal fuse going (Could I not wire a fuse across it to the fusebox or somethign, then just keep a sh!t load of fuses in the glove box?)...

Any help would be appreciated.
Thanks in advance MooZ :) :cool:
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MooZ
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Thu Jan 20, 2011 8:05 pm

Bump. Does nobody know anything?
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Brianmoooore
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Thu Jan 20, 2011 8:23 pm

The fuel flap motor is just a simple two wire lock motor with no complications like dead locks or microswitches. Peel back the boot liner on the RH side, see if it will move by hand, then unplug it and apply 12 volts to its pins, trying the wires both ways around.
If you cant unlock a door with the key with the lock motor disconnected, then the door has a mechanical fault
The solution to the thermal fuse blowing (otherwise known as doing what it is designed to do) is to fix the fault that's tripping it!
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MooZ
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Thu Jan 20, 2011 10:03 pm

I see, how do you disconnect the lock motors? simply unhook it from the mechanism? or unplug it electrically? I just took the screws out so it was free to move as you said. however, that didn't help anything. I wouldn't have thought it was mechanical as all of the 3 locks (two doors+ boot) are in the same situation. unmoveable to the unlock position....

As for causes of the trip, is there any popular causes I should check? Microswitches sticking on for too long?
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Brianmoooore
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Thu Jan 20, 2011 10:20 pm

Microswitches aren't responsible for the length of the pulse applied to the motors - that's controlled by the ECU.
There's no deadlock motor in the fuel flap motor or the driver's door motor, so if these can't be pushed in and out by hand, they are fried.
The fuel flap motor is easiest to check if you remove it physically and unplug it electrically.
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MooZ
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Thu Jan 20, 2011 10:25 pm

Thanks for the reply.

Hmm. I see. I'll check it again tomorrow. So if the ECU is responsible, maybe my new ECU from the breakers could fix the problem?
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Brianmoooore
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Thu Jan 20, 2011 10:29 pm

The ECU only normally gives trouble if it gets flooded. It then usually applies continuous power to the lock motors and fries them.
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MooZ
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Thu Jan 20, 2011 10:51 pm

Hmm it didn't look damaged TBF.

Come to think the locks only broke for the first time (what I assume to be the first time my uncle had the car for a good 10+years I don't think he had problems) recently, and it was the thermal fuse. Any further damage was caused by me soldering it back up with normal solder.

So I guess if I fix the motors and replace the ECU with my new untampered one, it could not go wrong again? maybe it was a one off that the thermal fuse went in the first place?
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