Central locking woes

[viz007]

I have a pre-facelift cabriolet.
A few months ago the central locking solenoid in the boot appeared to seize and I couldn't open the boot but the rest of the locks were still working. Luckily I managed to get in somehow after forcing the key a bit.

I replaced the boot solenoid and tested it ok a couple of times. Around 20 mins later when trying it again I could hear a buzzing from the boot (or it could have been the fuel cap solenoid) and now they have all stopped working and both the drivers and passengers side solenoids appear to be seized. I have managed to disconnect the door solenoids so have full access to the car.

The battery also seems to be draining within hours suddenly.

Do both door solenoids need replacing now or does this sound like an issue with the CLU? Are there any recommended replacement solenoids or is it a matter of buying used ones?

One other question, I tried the red/black wire mod. As I have a cabriolet, I was expecting to see 3 red/black wires coming from the A pillar but could only find 2, one going to the CLU and the other to the box next to it (light delay?) - I've joined these two together, does this sound right?
Thanks

[ChrisHC]

I expect Brianmoore will be along soon with a definitive answer, but it sounds to me as though the buzzing you heard was the boot solenoid activating continuously and that has caused the thermal cutout in the central locking ecu to operate. This has a spring held against a contact by low-melting point solder to complete the circuit. when overheating occurs, as from continuous operation of a solenoid, the solder melts and releases the sprung contact, breaking the circuit and stopping the current. If you extract the ecu from under the speaker in the driver's kickpanel, and open it up, you will see the open contacts. There will probably be enough solder around to reattach it, but if not do not use standard solder which will not give the required protection, a search on the internet will find you a supplier of the low-melting point stuff. Pictures of this are in the Wiki.

[viz007]

Thanks for your reply. I've just checked the thermal fuse and it looks fine. I've also checked Fuse 27 and itd also fine.

[Brianmoooore]

One other question, I tried the red/black wire mod. As I have a cabriolet, I was expecting to see 3 red/black wires coming from the A pillar but could only find 2, one going to the CLU and the other to the box next to it (light delay?) - I've joined these two together, does this sound right?
Thanks

Those two are already joined together at the other end. There's definitely a third one (the 12 volt supply) going into the A pillar.

[viz007]

Thanks. I've found the 3rd wire and joined them. It hasn't fixed my issue though.

Should the arm of the actuator/solenoids move in and out when disconnected and pushed by hand?

[Brianmoooore]

Should the arm of the actuator/solenoids move in and out when disconnected and pushed by hand?

Yes.

[viz007]

Thanks Brian
The situation now is:
-all 4 actuators (drivers side, passengers, petrol flap and boot) don't move when disconnected so appear to be burnt out.
-I have checked the CLU fuse and it looks fine and I can hear the CLU click when locking the drivers and passengers doors with the key but not from the boot.
-I have now successfully done the red/black mod

What should be the next thing I check?
Many thanks

[Brianmoooore]

This is beginning to sound like the relatively common disaster that happens to the locking ECU when it gets flooded as a result of blocked sill drains.
Take the locking ECU out and examine it for signs of water damage.

[viz007]

Thanks. I've not had a chance to access the CLU yet and check but I think this is the issue. The sill drains did appear to be blocked/draining very slowly so I have cleared these. If the CLU looks corroded, is it just a case of replacing the CLU and any burned out actuators?

[Brianmoooore]

If the CLU looks corroded, is it just a case of replacing the CLU and any burned out actuators?

AND clear the drain slots. The most common reason for them being blocked is over enthusiastic of underseal on the underside of the car.

[viz007]

Thanks Brian. I've poked a small screwdriver into the 2 drain holes and some crud came out with water and it appears to be flowing a bit faster now. Any other tricks to clearing these?

[Brianmoooore]

You can clean the front ones from inside when you have the locking ECU out.

[viz007]

Hi. I have cleaned the drains and am looking for replacement actuators now. Should I be looking at used ones via breakers or are there any new ones that can be recommended?

[Brianmoooore]

The only ones that will be a direct replacement are genuine E30 ones, and second hand one should be absolutely fine. I've never come across one that has failed, other than those that have been killed by a flooding incident.
Note that the lock motor design was totally changed in mid '90, to lock motors that were integral with the door latches. These are nowhere near as reliable as the earlier type.

[Contours]

I have had a couple of them seize over the years so had to be replaced. They are quite expensive to buy. I disconnected the fuel tank one and used a locking petrol cap instead so am only concerned with three actuators and they have been operating well for some time. I could be wrong but I think that the fewer of them that are in the system the better. Not recommending shortcuts or anything.

[Radar]

I seem to have almost identical problems. My central locking control relay is fine, I now have a good one in place and 2 spare good ones. The red black mod seems to have been done. I have the newer (unreliable) type door actuators my car is a ‘91 M3 convertible.

When operating the locks and manually tripping the relays on the CLU, I can hear clicks at all the doors, but no movement from any actuator, either up or down. I have the driver’s door one out (had to remove window track to access it). I have a set of used spare old style actuator.

Is there a way to test the actuators? Will one bad one stop all the others working?

With it broken, it leaves everything totally locked up and I can’t even open it on the key. I’ve managed to open it up by slightly forcing the locks and lifting the door handle at the same time.

I’m almost at the point of ordering a full set of new actuators and to heck with the cost. However I’m reluctant in case this doesn’t solve the problem.

I should add that yes, my original CLU had been flooded and looked like something from the Titanic. Replacing it with a good unit had everything working fine for some time, though it was sometimes reluctant to stay locked. Could the flooded CLU have damaged the door actuators and only now they’re failing? Does one bad actuator stop the rest from working?

[Ukhozi]

All actuators work the same way so disconnecting them and apply at least 9V (PP3 battery?) or 12v will make then open and when revered, close. if they don't they are toast.
I they do open and close it's the control unit.

[Radar]

All actuators work the same way so disconnecting them and apply at least 9V (PP3 battery?) or 12v will make then open and when revered, close. if they don't they are toast.
I they do open and close it's the control unit.

Thanks... but there’s 5 wires on each actuator, which ones do I apply voltage to?

[Brianmoooore]

Lock motor wires are plain white and plain blue. Deadlock motor wires are (same) blue and plain black.

IIRC, the problem with the later actuators is that the built in switches can get decoupled from the motors, leaving the switch giving, for instance, a permanent 'lock request' signal, when the motors are in any position, which the older type are unlikely to do.
You can pull the plugs from each motor in turn to check for problems like this. 'A' pillar door loom plugs will do for the front door actuators, if you can't reach the plugs on them.

[Radar]

Thanks, it’s at the workshop now, I’ll have a better look and test some bits next time I’m there.

[Radar]

That was a long process. I knew it would be long and tedious, that's why I sent it to my local workshop... who also knew it would be complicated.

I ended up using my friendly mechanic's facilities and advice to test and replace a selection of central locking CUs, then I replaced ALL the actuators. New ones for the door and used ones for the boot and fuel flap. I skipped the glove box.

It seemed to work ok so long as the boot was locked but was still temperamental.

I knew I had multiple issues with the C40X door connectors, so I needed to fix them to rule them out. The pins were awfully corroded, some had been bypassed and included some well dodgy looking crimped connections with no respect for the original wiring colours. The housings themselves had gone brown and crunchy. I took a further mortgage to purchase all the pins (and some spares) from Cotswold BMW (many thanks!) I already had the plug housings, as I'd known I had issues with these plugs for years, mirrors had stopped working and so on. I managed to find all the necessary cable colours from vehiclewiringproducts.co.uk. I would note that pins 21 on both C40X connectors are shown in the Wiki as Green/Yellow for the tweeter. Mine were Grey/Yellow. It took two full days to complete these plugs and a couple of other small jobs (new window rubbers inside and out and a Bremen SQR 46). I was super careful, some pins had more than one wire run in to them and some colours were on more than one pin; because of the old repairs/bodges, I spent ages with a multimeter checking and double checking where things should go. Once complete, my mirrors worked fully for the first time in years.

The central locking still only worked both ways with the boot locked, but not the boot. I ordered yet another boot actuator, this time a brand new one, not a 'tested' used one. I've just fitted it and everything works perfectly.

Now all is well in the world. Central locking works a treat, mirrors work as they should, temperamental window motors are no longer sketchy and I'm no longer worried about short circuits emanating from my C40X plugs.

It's fair to say that my central locking issues were not one single fault. I'm not sure what happened first, I definitely had a bad central locking CU (the low temp solder fuse had popped) and an earlier one had been flooded (looks like a relic from the titanic), I also had bad door actuators and as it turned out I suffered two bad boot actuators (my original and the used replacement). This may have been caused by short circuits from the C40X plugs or from the CU failures.

Now the cost... I paid a little to my mechanic for the use of his premises 2-3 days, tools, advice and some early diagnostics. The rest was on me, about 50% of it outside in the weather on my drive:
£100 Wiring products (cable and solder/heatshrink/joiners, decent crimping pliers)
£553 Central locking actuators (both new and used) Schmeidmann - top tip - don't bother with used
£323 Cotswold BMW C40X pins
£40 used Central Locking CU from eBay
£40 additional C40X parts from EU
£100 to mechanic
£140 NOS Interior light relay/timer (this was bad too)
£??? cost of new window rubbers that I ruined changing the door actuators until I learnt how. They were old and crunchy anyway.

So the best part of £1.5k and days and hours of my time. It's worth it to have it all working. Satisfying to have done it myself and not paid a shit ton of labour.

[Radar]

Does anyone know the part numbers for the pins and connector for the central locking control relay ?