Central locking issue

[Biggs]

I've searched Google and most of the forums looking for an answer....

Basically I can't lock the car using the remote or lock all doors with the key either. When the lock button is pressed on the key/fob a short blip sounds from the alarm siren as if to say a door isn't closed properly etc..

Each door when opened displays on the dash inc bonnet and boot so it appears each lock switch is working as it should.

The micro switches in the drivers door lock appear to be working OK as one way will open all doors and the other will lock that door only and also sound the siren blip as above.

When I disconnect/ reconnect the fuse for the central locking the system works as it should.....I can lock/unlock 100 times and everything works as it should until the engine is started..stopped then back to the fault again.

When the fault is present I can't lock the doors from the interior lock button either.

Anti hijack works as should and locks all doors at x mph. Not sure what else it can be. Anybody got any ideas?

[ceedy]

think there is a unrelated fuse that goes and can cause locking problems, Check fuse 36 passenger compartment fusebox,

C

[Biggs]

I'll give it a try, but if the battery is disconnected for half hour or so to reset the bcu the locking/unlocking works as it should. Until the engine is started......May have to get it plugged in. Anybody got the software and knowhow in the South Yorkshire area?

[Tim]

I wounder if the fuse is the wrong one, would the engine electrical surge trip the solenoid out? Or could it be an earthing issue.

[Biggs]

I've ordered a diagnostics kit from pscan.uk. hopefully the bcu will be able to tell me what its not happy with.
I shall also look into the earthing side of things as that can play havoc with stuff like this. Good shout Tim.

I'll keep this thread updated with my findings should somebody else have the same issue.

[Biggs]

Quick question..just need to know if the alarm is supposed to sound a blip when the car is locked?

I've pulled the fuse again so the central locking is working but still have the blip/ chirp when the car is locked from the fob. Alarm led on the dash lights up when locking.

[David]

Shouldn't do that. Looks like it 'thinks' a door, bonnet, or boot-lid etc. is still open, and warns that it can't lock/arm.
I also get that if I remove the key from the ignition clumsily, when still sat in the driver's seat, and accidentally press the fob lock button.
Doesn't lock anything then though, just complains. However, if I don't press the fob unlock then, it DOES set off the siren as soon as I open the door, so has actually armed (kind of).

A successful remote button lock results in no chirp, just a very rapidly flashing red LED for about 10 seconds. Thereafter the alarm is armed, and the LED flashes once every 3 to 4 seconds or so... on my car anyway!

David

[Biggs]

OK thanks ��

I have the laptop connected now and its showing the inertia switch as tripped!? All door and lock switches are OK.

[David]

OK thanks ��

I have the laptop connected now and its showing the inertia switch as tripped!? All door and lock switches are OK.
Good news!. Try a reset of the inertia switch cut-off button back of the glove box by the A-post, and see what happens.
Clean the connections too. Sometimes they just plain fail, or can be so sensitive that they can let you down. Best to replace if that appears to be the case. Not specific 260 and easy to find, I believe.

Edit (David). Think if the inertia switch had tripped, you would not be able to start the car at all, so maybe I was leading you up the garden path. Sorry.

David

[Biggs]

I'll get it out and have a look, but yes the car is running, seems odd the bcu saying its tripped. Apart from that everything else on the bcu looks to be ok.
The alarm light on the dash flashes slowly for around 10 seconds after locking indicating a mislock of some description.

[David]

If needed: https://rimmerbros.com/Item--i-WQT100030
... or any scrapyard with a petrol R75 in it

David

[Nich]

I'll get it out and have a look, but yes the car is running, seems odd the bcu saying its tripped. Apart from that everything else on the bcu looks to be ok.
The alarm light on the dash flashes slowly for around 10 seconds after locking indicating a mislock of some description.


You really do need to get your questionnaire back to Tim to get full access to this site. A lot of the information you are looking for is already available to full members.

Nich.

[Biggs]

You really do need to get your questionnaire back to Tim to get full access to this site. A lot of the information you are looking for is already available to full members.

Nich.

Already done......sent back same day. Just waiting on Tim?

[Biggs]

If needed: https://rimmerbros.com/Item--i-WQT100030
... or any scrapyard with a petrol R75 in it

David

Thanks David. I'll look into this tomorrow.

[Nich]

Welcome to full membership James.

Nich.

[Biggs]

Welcome to full membership James.

Nich.

Top man. Thanks ��

[Biggs]

I'm looking at changing the bcu as it still showing the inertia switch as tripped and still not getting anywhere with the central locking issue either.

Is it just a straight swap for 2nd hand unit of the same type? Or does it need programming?

[jeff turbo]

I had a problem once similar to yours, it opened but bleeped but wouldn't lock or via the key and the dash display said doors were open, I had to change the drivers door central locking mechanism as I traced it to that. After I replaced it, it worked perfectly and I didn't need to program anything, all Rover 75 and ZT mechanisms are the same from memory. I took the old one apart and found a small plastic lever had moved to where it shouldn't be so the lock wouldn't work properly. I put that part back, put it another car and it started working again. The bit I'm not getting is it works after disconnecting the battery until you start the car but you may want to try changing the drivers door central locking mechanism as that could be faulty as per mine, there are a couple on ebay at about £65 (as always the drivers door is more expensive) or if you have a breakers near you you may get it cheaper if you want to try that, to change the BCU you might need the car T'4ed and one that will talk to the innards of the car but sometimes a normal T4 doesn't work on 260s as I've been told a few times by those who have a T4 computer. There are also different BCUs depending on if yours is a facelift or not

[Biggs]

Before I had the laptop plugged in I had the drivers lock completely out and inspected. I'm confident it's good. The new diagnostics software shows all doors are closed and door micro switches are working. I have had the inertia switch out today and that checks out ok. Whilst under there found the sunroof drains completely detached from the rubber outlet. Both sides aswell..... rears look OK but a loose fit in the rubbers. Repair kit on order......

[David]

... Rover 75 and ZT mechanisms are the same from memory ...
Indeed Jeff. As you imply, each of the lock units is however unique to its position on the car, i.e. front-left, front-right, rear-left and rear-right. (Front locks only, will also differ between LHD/RHD cars). There are two version of rear locks however, with or without the child-lock built in.

Here is the child-lock tab to identify the version:

15197

David

[David]

Also, take a good read of this maybe:
https://www.two-sixties.co.uk/mgoc260/html/f0rum/showthread.php?18877-Water-ingress-into-the-wiring-loom (https://www.two-sixties.co.uk/mgoc260/html/f0rum/showthread.php?18877-Water-ingress-into-the-wiring-loom&highlight=blue)
You may recognise some of the symptoms, if you have/have had bad water ingress.

David

[jeff turbo]

Indeed Jeff. As you imply, each of the lock units is however unique to its position on the car, i.e. front-left, front-right, rear-left and rear-right. (Front locks only, will also differ between LHD/RHD cars). There are two version of rear locks however, with or without the child-lock built in.

Here is the child-lock tab to identify the version:

15197

David

Hi David, yes I know that but I was only talking about the drivers door mechanism in the UK.

[David]

Hi David, yes I know that but I was only talking about the drivers door mechanism in the UK.
Yup. Just to 'round the circle' for readers in the future :D

David

[Biggs]

Everything else works as it should. Just the annoying locking issue. I've ordered another bcu and if needs be ill send it off for programming. Hopefully this should sort it. Can't find any water ingress/damage on the bcu. Carpets/floors are dry. But there is evidence of previous water ingress inside the car.

[David]

As a matter of interest, what was the number on your existing BCU, and did you managed to find the same? Rimmer's are listing it as YWC001522 (or YWC001512 for front windows only).

Quite a few new 1522's are on the 'Bay at around 50 quid I see, largely because they generally only go wrong when they've been swimming, I imagine. Lots of (used) 1512 ones too, but that is from cars converted from 2 to 4 elec. windows configuration, I suspect.

In any event I think you will find that a T4 session with the car will be needed, rather than sending off the BCU for "programming". If that is the case, it will also be interesting to see if the T4 sees the same as your tester, namely a tripped inertia switch, before you do the swap.

David

[Biggs]

Yes, its the same unit. 511. Let you know how i get on when it arrives. It also shows power to the windows when there's not.....

[David]

Yes that shows up as LOW, front elec. windows only, as far as I can see.

The slightly different number gels with what Rimmer's also say :
"YWC001512 - Genuine MG Rover. Original part number was YWC001511."
"YWC001522 - Genuine MG Rover. Original part number was YWC001521."

David

[OneSixty]

Did you have any joy with this Biggs?

[David]

Wouldn't hold your breath on that Ben, since 'Biggs' hasn't logged on to the Forum in over 2 months. You could try a PM (his profile shows no 'Send email' option); he may have PM notification switched on.

David