Central Locking Failure

Fri Dec 05, 2008 4:43 pm

Hi guys,
I hope you can help.
My central locking is completely non-existant, I have to lock and unlock each door / boot seperately in order to get in.
The guy I bought the car off (93 tourer) said that the central locking was faulty when he purchased it , but had it fixed by an auto electrician after about 3 hours labour...only for it to fail again a few weeks before selling to me.

Now im useless at electric work so any answers please make as simple as possible.... I have a multimeter , but only just about know how to turn it on..

Where should I start?
Im tempted to replace the entire c/locking relay as they are fairly cheap to come by and im hoping it may do the trick...where are they located in the car?

Do you have any other tips or ideas to try and narrow the problem down?

Fri Dec 05, 2008 4:47 pm

The relay is located in the driver side footwell behind the speaker.
Before you do that, take out the relay and see if it has any water damage to it.
Do a search for RED/BLACK in the tech section under user name brianmoooore.
This usually cures the problem for most people.
Hth

Mon Dec 08, 2008 4:01 pm

My relay box was full of rusty water!!! where does it come from?!

currently searching for a replacement, fingers crossed it will do the job, although my drivers side door has a strange prob in itself.
when i lock it with the key, if you then go to open it with the handle, the door goes to open but only opens about half and inch...like its not been shut properly.
then if you push it shut it remains firmly locked.
The door locking pin is also fairly rough in operation when you pull it up and down.

could these faults be something to do with the state of the lock when the central locking failed or a mechanical fault perhaps?

Also, it appears on a previous attempt to repair the wiring an electrician has cut the infamous black/red wire and spliced it to another wire...it think a green one perhaps? what would that be for and will it affect my locking when I plug in a new relay?

Mon Dec 08, 2008 5:50 pm

My relay box was full of rusty water!!! where does it come from?!

Usually blocked drains in the footwells

Posted: Mon Dec 08, 2008 4:01 pm Post subject: Re: Central Locking Failure

My relay box was full of rusty water!!! where does it come from?!

currently searching for a replacement, fingers crossed it will do the job, although my drivers side door has a strange prob in itself.
when i lock it with the key, if you then go to open it with the handle, the door goes to open but only opens about half and inch...like its not been shut properly.
then if you push it shut it remains firmly locked.
The door locking pin is also fairly rough in operation when you pull it up and down.

could these faults be something to do with the state of the lock when the central locking failed or a mechanical fault perhaps?

Faulty L shape lever behind the doorlock as these tend to wear, but I have the same problem, when you get the c/l working this seems to disappear.

Also, it appears on a previous attempt to repair the wiring an electrician has cut the infamous black/red wire and spliced it to another wire...it think a green one perhaps? what would that be for and will it affect my locking when I plug in a new relay?

Not sure on that one, that's one defo for mr moooore , but i would think it would as the mod is for the 3 red/black wires only, not for any other coloured wires.HTH

Mon Dec 08, 2008 7:47 pm

Water is supposed to get into the sill - there's a pipe bringing it there from the sunroof. What it's not supposed to do is stay in there! Check the drain slots in the bottom of the sill.
Pull out the locking ECU, unplug it, and connect a 21W 12V bulb across the red/black and brown wires on its socket. It should light to full brightness.
Where is this red/black wire connected to a green wire, and in which direction do the wires go from the join?
If the locking ECU has water damage, then you need to replace it. Damaged ones have a nasty habit of dead locking all the doors, then frying the lock motors!

Tue Dec 09, 2008 11:10 am

thanks guys, will report back when ive tried a new relay and checked the strange wiring..

fingers crossed it will all work regardless

Tue Dec 09, 2008 12:01 pm

Don't connect up a new 'relay' if there's any suspicion of the lock motors being fried! You need to test them first.

Wed Dec 10, 2008 2:36 pm

I threw caution to the wind and plugged in a replacement c.locking unit, and hey presto, working central locking! , even the drivers door works properly now, although there is a small amount of resistance on the key when unloking on the drivers barrel, im presumming wear and tear?

I checked the spliced red/black cable quickly, its connected to a blue/green cable at the terminal connection, running back into the loom. any ideas why? it all seems to be working properly so for the moment at least im happy.

Thu Dec 11, 2008 10:29 pm

Brodie320 wrote:I checked the spliced red/black cable quickly, its connected to a blue/green cable at the terminal connection, running back into the loom. any ideas why?

I suspect the blue/green is a bit of wire that's been added in for a repair. To be a permanent live, like the red/black, the main colour of the other wire would be red or grey.
Check that the locking stops working if you pull out fuse 27.