Central locking problem - not relay tho

[Spion]

My central locking has packed up. The car has the red-black mod, and the relay is fine, AFAIK.

This seems to be a problem with the locking mechanism in the door. Is there a common fault with the switching system operated by the lock?

Can something go wrong with the mechanical action of turning the key?

Can there be problems with the solenoid in the door?

I'm just looking for some clues before I rip the door card off and go in there looking.

Cheers

[eko]

Could be the pins are dirty/corroded in the A pillar socket.
Pull back the rubber cover,press the 2 tabs together and pull the socket out to have a look.

[asmith88]

have you tried taking the door card off and making sure the microswitch is making contact?

[daimlerman]

Turning the key mechanicaly pulls the locking pin down whilst also operating the locking solinoid that signals the other locks to lock/unlock.Also trips a micro switch that is part of the system.
First check is to make sure that everything moves smoothly and is properly connected.
It can be difficult to see inside the door to check all the bits,so patience is a good tool to dig out of your toolkit!

[Brianmoooore]

and the relay is fine, AFAIK.

What makes you think this?

[Spion]

and the relay is fine, AFAIK.

What makes you think this?

Because the main problem has been getting the lock to work correctly mechanically. Over the course of a few weeks, when I have been able to make the key turn properly, the electrical part of the process has gone from intermittent to not working at all - and that makes me think there's something wrong at the first stage of the process. Of course there could be a prob with the relay but I figure that I first need to check what's wrong inside the door, as things are definitely not right with the actual lock.

[Brianmoooore]

If you've been working on the locking and operating it many times in quick succession, you will have been stressing the thermal overload inside the locking ECU, so there's a chance this has popped. If so, there will be no activity from the electric locking whatsoever, so could be worth checking.
If it has tripped, re solder the spring using the original solder only.
Also, connect a 12 volt bulb across the red/black and brown wires at the ECU plug, to check that power is reaching it.
There are things that can go wrong with the mechanism the key operates, but this is unlikely to affect all three key mechanisms at the same time!

[Spion]

If you've been working on the locking and operating it many times in quick succession, you will have been stressing the thermal overload inside the locking ECU, so there's a chance this has popped. If so, there will be no activity from the electric locking whatsoever, so could be worth checking.
If it has tripped, re solder the spring using the original solder only.
Also, connect a 12 volt bulb across the red/black and brown wires at the ECU plug, to check that power is reaching it.
There are things that can go wrong with the mechanism the key operates, but this is unlikely to affect all three key mechanisms at the same time!

Yes, I will take a look at the relay. It's quick n easy to get to.

There is something up with the lock tho. It won't do the 45deg 'open' movement. It only goes 90deg to the 'mechanical' open posn. Had the door card off this afternoon but it was impossible to discern anything by feel.

[Brianmoooore]

It won't do the 45deg 'open' movement. It only goes 90deg to the 'mechanical' open posn.

This is usually the L shaped alloy piece on the back of the lock barrel seized up, and not toggling from side to side as it should.

[Spion]

It won't do the 45deg 'open' movement. It only goes 90deg to the 'mechanical' open posn.

This is usually the L shaped alloy piece on the back of the lock barrel seized up, and not toggling from side to side as it should.

Any tips on how to get the barrel out? There's not much room in the door space. I might need to kidnap a child to get in there

[Brianmoooore]

Flip the big C clip off with a long screwdriver , through the hole provided in the inner skin, and just pull the barrel assembley out.

[Spion]

Flip the big C clip off with a long screwdriver , through the hole provided in the inner skin, and just pull the barrel assembley out.

How easy is it to get the C clip back on? I just want to know before I start the job so I can 'reverse' out of it if need be

[Brianmoooore]

Depends how good you are at keyhole surgery!
If you want to get your hand in there, a single bolt holds the bottom of the widow glass guide, which is the main thing in the way.
After removing the bolt, pull the steel channel of the guide down around 10mm, letting the fabric/rubber part inside of it slide up in the channel. The bottom part of the steel channel will unclip from the top half just at the bottom of the glass, and can then be swung up out of the way towards the window motor.

[Spion]

So I got the barrel out (what a f*king game that was!) and put a new one in but the problem's still the same.

IE, I can turn the key thru 45degrees to unlock it, but have to lock the driver's door by pressing down the inside lock button before closing the door. All that happens when I turn the key in the locking direction is, well, nothing. The barrel peg is engaged with the latch slot.

Any ideas anyone?

Still no sign of life from the central locking, which could be the relay. But for now I want to get the locking working properly mechanically

[Brianmoooore]

Does the old one toggle from side to side when you hold the barrel in your hand and turn it with the key?
Does the new one?
Don't blindly replace things without checking exactly what the problem is!

[Spion]

When I got the old barrel out the micro switch the barrel works against was stuck down.

Anyway, latest news is the relay was full of water and burnt out beyond repair.

So, now I'll get another relay and see where that gets me.

[Brianmoooore]

You should have a look at the sill drain slots as well!

[Spion]

You should have a look at the sill drain slots as well!

I felt down inside where the relay sits and all was dry, which was a bit baffling. I reckon the relay was facing upwards and got an unlucky flooding from the sunroof drains in the recent wet/snowy/thaw weather.

[Brianmoooore]

I reckon the relay was facing upwards and got an unlucky flooding from the sunroof drains .

When the relay is in place, it's upright and about 2" clear of the sill bottom.

[Spion]

So I put the new relay in. It clicks* when I operate the lock button but the C Locking is not activated.

So, where next?


(*One of the little coil things is actuated by this, as I took a look with the electronics outside the plastic box.)

[Brianmoooore]

Connect a 12 volt bulb across the red/black wire and brown wire at the locking ECU's plug. It should light at full brightness.
Does it stay at full brightness when you operate the locks?

[Spion]

Connect a 12 volt bulb across the red/black wire and brown wire at the locking ECU's plug.

When you say the 'locking ECU plug' do you mean the white plastic one that plugs into the relay?

I'll get to this early next week as I'm 70 miles from my circuit tester right now

[Brianmoooore]

When you say the 'locking ECU plug' do you mean the white plastic one that plugs into the relay?

Yes, with the ECU still plugged in.

[Spion]

Connect a 12 volt bulb across the red/black wire and brown wire at the locking ECU's plug. It should light at full brightness.
Does it stay at full brightness when you operate the locks?

I put the circuit tester across the red/black and brown wires. It showed 12v and dipped a little - maybe 1v max - as I pulled the door lock button to the unlocked posn.

What does that tell me?

[yetta]

Hi just noticed the date of your post after working on my 1990 E30 central locking fault today. It is exactly the same problem on mine, Cant open the petrol cap or lock the doors with the key. Have had the door lock to bits and just put it back so will watch this post with great interest as I am now stuck. My relay also clicks but nothing else works. Dont know what I would do without all this tech info Great Forum Thanks John

[Brianmoooore]

I put the circuit tester across the red/black and brown wires. It showed 12v and dipped a little - maybe 1v max - as I pulled the door lock button to the unlocked posn.

What does that tell me?

That is just about as it should be.
You say that the original locking ECU had been waterlogged. Unfortunately, when this happens, the ECU has a nasty habit of powering the solenoids continuously, and frying them.
I think the next step has to be to unplug all the lock motors, try them one at a time, to see if any have survived, and if still nothing works, try one fresh motor and confirm that it works.

[Spion]

OK, I thought as much.

Do you know how they're fixed/connected?

[Brianmoooore]

Unless you have one of the very last E30s, where the lock motors are mounted on the door latch assemblies, like later BMWs, all the motors, except the fuel flap, are mounted by a couple of small self tapping screws with a steel wire link between them and the latch.
Remove the screws and twist the motors to unhook the links.

[Spion]

I swapped out one solenoid and sure enough the new one worked. I've got a set of used ones on the way now from Chris Warburton so hopefully I'll get the job done the coming weekend.

Thanks for your help on this, Brian. You're a star