Central Locking

[ChrisHC]

I am very new to E30 ownership but have quickly learnt all about problems with the locks. I have built up a new driver's door lock which has cured its previous wayward behaviour and moved on to the central locking which showed no signs of life. I read of the red/black wire problem and investigated that, finding it had already been tackled, although I in fact re-did it. Then I investigated the central locking relay and found that the thermal cut-out had operated. I re-soldered that and tried the system. It tried to work, but the actuator on the passenger door was straining unsuccessfully to move the lock. Having initiated that, there was nothing I could do to stop the straining, so I was starting to disconnect the battery when it fell quiet. On investigation I found the thermal cut-out had operated again, not surprisingly. I took off the passenger's door card and found the actuator was only held on by one self tapper. I put that right and lubricated the mechanism, which left it working smoothly. I again soldered up the thermal cut-out and hoped for great things, but in vain. The CL relay looked as though it had been immersed in rusty water for a while and one of the relay springs was missing, so I sourced a replacement from a breaker. This does not have the detachable end of my original but otherwise appears the same and plugged into the socket. Sadly, there was still no sign of life from the actuators. I checked the fuse, and now I am baffled. I have not taken the multipin plug on the door apart, but that seems unlikely to be the problem, since the system was trying to operate previously. Has anyone any thoughts about what to do next? The car has been fitted with an anti/theft device which wired into the loom just before the central locking relay, but is not working. Is it worth considering going to keyless locking, and if so what is the best kit?

[Brianmoooore]

Brian will also be along sometime

Morning!
The rusty water marks in your original locking ECU indicate that it has been immersed in water, usually as a result of the sill drainage slots being blocked, so that is something that needs addressing.
Sadly, this water immersion is the worst thing that can happen to an E30 locking system. It usually results in the ECU applying constant power to all the locking motors, instead of just a short pulse, which results in them burning out. Any that survive is a bonus.
The fuse in the system only provides short circuit protection. Overload protection is provided solely by the thermal fuse in the ECU, which provides protection against fire, but doesn't always operate quickly enough to save the motors. Note that the spring is soldered in place with a special low melting point solder, so
if you do try to reset it it is very important that no new ordinary solder is added, otherwise the 'fuse' will be useless.
I've never seen a locking ECU that can't be opened up and inspected, so I suspect that it might have been sealed by someone with the same problem as you, and might be equally dud.
The whole locking system is extremely reliable, once the 'red/black' wire mod. is done, and I would certainly recommend repairing it, rather than replacing it with some infinitely inferior quality aftermarket stuff. Having said that, adding a remote locking module (search for 'rightclick') to the system is recommended, both for convenience, and to save wear on the lock barrels and linkage.
Carry on with what willnz suggests. The idea is to establish that power is available at the ECU plug, and to test each actuator in turn, until you can reliably operate the locking using wire links in the ECU plug. Only then should you consider plugging in an ECU.

[ChrisHC]

Thanks for that, willnz, looks like very useful advice. The wrecker did not say that the relay was tested, so that could be at fault, but since the system was straining to work with the old relay, then nothing and nothing with the replacement, it seems more likely that something else has gone wrong.
The car is a two door (325i Sport)
I have checked fuse 27

[Brianmoooore]

test each actuator in turn, until you can reliably operate the locking using wire links in the ECU plug. Only then should you consider plugging in an ECU.

[ChrisHC]

Brian, the wrecker's ECU is identical to the original except that the plug end is one solid piece, rather than a removable lid that fits over the tines of the plug. It looks as though access is gained through a plain lid at the other end, I have not tried levering that off but it does not look as though it simply unclips. The codes on it are similar but not identical to the original, and it gives the impression of being a slightly re-designed item.
I did source some low melting point solder to re-fix the thermal cut-out.
It might well be that straining to operate the lock has burnt out the passenger door motor before the thermal cut-out operated I suppose.
My thinking on remote locking was that the original ECU would not then be required, is that correct? As well of course as being a useful feature anyway. I will certainly look at the RightClick products, at a quick glance they look much better than anything I had found.
I was wondering how to check the lock actuators individually, so the advice here has been invaluable.

[BenHar]

I did source some low melting point solder to re-fix the thermal cut-out.

Where did you get it from, please?

Thanks
Ben

[ChrisHC]

I did source some low melting point solder to re-fix the thermal cut-out.

Where did you get it from, please?

Thanks
Ben

I Googled it and found some on Amazon Marketplace from BGA-Reworking UK althoughwhen it arrived it was supplied by Insat International. 1 metre of 0.8mm solder wire cost £7.00 post free.
LINK

[Brianmoooore]

I did source some low melting point solder to re-fix the thermal cut-out.

Where did you get it from, please?

Thanks
Ben

I Googled it and found some on Amazon Marketplace from BGA-Reworking UK althoughwhen it arrived it was supplied by Insat International. 1 metre of 0.8mm solder wire cost £7.00 post free.
LINK

There are lots of mixes for low temp. solder, with an equal number of different melting points. I have no idea which mix BMW used.

[Brianmoooore]

The Rightclick remote locking modules still uses the original locking ECU. They also do a central locking kit, but this will be tat compared to the OE BMW stuff.
The locking ECUs are ultra reliable, as long as they haven't been drowned, so a second hand one shouldn't be expensive. Same unit on all models.
As I've said in a previous post, the trick is to get the locking all working with wire links in the ECU plug, but only apply short pulses.

[ChrisHC]

Many thanks, everything is now working. When I unplugged the passenger door actuator, all the others worked. I therefore took it out, thinking it needed replacement, but when I tried it out of the car it worked. One of the wires did have some insulation missing so possibly it was shorting somewhere, but when I put tape on that and replaced and adjusted the actuator it worked perfectly. The fuel flap did not lock because the pin was not coming out far enough, but some lubrication cured that. The boot latch was also dry and stiff so I lubricated everything and it now works smoothly. The RightClick remote locking kit is on order.

Just one question, when the central locking is unlocked, the boot still needs to be opened with a key ie simply pushing in the barrel does not open it, the key needs to be in it and turned when the barrel is pushed in. Looking at the mechanism and reading the handbook, it seems that is way it is meant to operate, is that correct?

Thanks again for the help.

[ChrisHC]

Thanks, willnz. It appears then that it needs adjustment, with doors unlocked and boot lock horizontal it will not open by pushing the button. With doors unlocked and boot lock vertical, pressing it in without the key in it operates the central locking, to my surprise!

Is there anything online about this adjustment?

[ChrisHC]

I will try that, thanks.