Release cheater panel it says....

P38 Monkey said:

A most excellent test - simple enough and very revealing.
CDL motor is close to open circuit (1.5MΩ) so that is one duff motor.
The superlock motor is a bit below the lower end of the tolerance so is probably OK.
While the door card is off I checked what voltage is being sent to the CDL motor on central locking - a very short pulse that my meter showed was a volt or so, but it was over as soon as it began.
Good used latch from East Coast 4x4 is probably the way forward...any favourite used parts suppliers that I should be aware of?

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MGF motors from the same year have the same motors at a fraction of the cost. The motors just clip in and out.

tomcat59alan said:

Well I've tried to go paperless and it's been a nightmare, since Monday,, flights ,boarding passes, CPR tests, passenger locator forms,car hire, car hire excess insurance , travel insurance, vaccination certificate and more to come, I've accounted for half a forest in Finland.

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I guess as long as it is in your house somewhere it counts as carbon capture.

Grrrrrr said:

MGF motors from the same year have the same motors at a fraction of the cost. The motors just clip in and out.

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The whole latch assembly for the MGF looks the same as the P38 one. The motors look as they are held in by some screws but who knows what lies beneath... Searching for separate motors does not reveal anything though. I live 2 miles from the MGOC Spares Counter but they only sell complete latch assemblies for around £120. Do you have a source for the motors?

P38 Monkey said:

The whole latch assembly for the MGF looks the same as the P38 one. The motors look as they are held in by some screws but who knows what lies beneath... Searching for separate motors does not reveal anything though. I live 2 miles from the MGOC Spares Counter but they only sell complete latch assemblies for around £120. Do you have a source for the motors?

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I don't. I put some out of the MGF lock I got off the Bay in mine. Martyuk might as he sells fully refurbished ones on his p38 spares website. He upgrades the microswitches too which is definitely a good thing as the boot lock grounds through the centre one and burns it out.

P38 Monkey said:

The whole latch assembly for the MGF looks the same as the P38 one. The motors look as they are held in by some screws but who knows what lies beneath... Searching for separate motors does not reveal anything though. I live 2 miles from the MGOC Spares Counter but they only sell complete latch assemblies for around £120. Do you have a source for the motors?

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I used an MGTF lock, there's an extra metal bit that's not needed and can be cut off.

tomcat59alan said:

I used an MGTF lock, there's an extra metal bit that's not needed and can be cut off.

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If the rear locks are cheaper you could always use the motor's out of them.

Sorry I am somewhat late to the party here... As others have mentioned, I am out of the UK at the moment and not entirely sure when I will be back yet - covid and work is kind of steering that one!

It sounds like you have sorted out your locking issues - but a few bits for you to note...

The locking motors are 12V - but they are only operated (as others have mentioned) with a short pulse (about 100ms from memory) of power from the BECM. Lock/Unlock is controlled by reversing the polarity. There is a common ground wire, as you will have seen the the test sheet, and then a second wire for the CDL motor, and one for the superlock motor. If you ground the common wire and tap 12V onto the other wire, it should lock the latch... reversing so +ve on common and -ve on CDL wire will make it unlock.

It is not unusual on the older P38's for both front latches to fail and have the locking motors burn out. The common issue with RF interference would cause older BECMs to freak out if they were bombarded with RF - and as a result they would continually try to lock the doors for some reason, and the constant 12V onto the locking motors would then burn them out, which is most likely the case for you. I don't know why the rears never seemed to burn out - but they are controlled together directly from the BECM - whereas the front locks are controlled by door outstations in the front doors - and the BECM talks to them over a serial link.

The symptoms you have described about how your locking is working - suggests to me that both front latches have burnt out motors and replacing them should get the locking working properly again. I would also look at seeing what RF receiver is fitted as the later ones filter out more RF, and the 3rd gen one and an aftermarket unit myself and a mate designed both actually filter everything but P38 key transmissions out, to stop the BECM from being woken up all the time and draining the battery - but also because all the spurious RF is filtered out, it stops the BECM from being swamped and burning the motors out too. Unfortunately the RF filter unit we make is out of stock at the moment - I am awaiting my mate to make some more of them - and I can't really do much about that from the other side of the world!

Hope this helps, but it sounds like you've got to the root cause already!

A very timely update - thank you... I am sorting out the passenger door first and then will move on to the drivers door.
Your test sheet is brilliant and it enabled me easily to ascertain that the motors are duff.
Presumably the RF receivers are in each door and are the black-boxes fitted lower down.
Mine are E26640 - AMR2909: are they ones with decent filters?
If not, (and pending availability of your version), if I wanted to start by just using key central locking and not remote locking, can I just unplug those two boxes?
This car is a Japanese import and had some electronics in it - old DVD-based GPS system and a TV terrestrial receiver, so probably a lot of RF floating around near the receivers. But that is all removed now.
There are two green/black wires coming out of the receiver that make their way round to the bottom of the door and are cut there. They appear to be heading for a two-way connector fixed in the bottom of the door cavity that has two black wires coming out of it, but they too are cut. Any thoughts as to what they might be?
Many thanks once again....

P38 Monkey said:

A very timely update - thank you... I am sorting out the passenger door first and then will move on to the drivers door.
Your test sheet is brilliant and it enabled me easily to ascertain that the motors are duff.
Presumably the RF receivers are in each door and are the black-boxes fitted lower down.
Mine are E26640 - AMR2909: are they ones with decent filters?
If not, (and pending availability of your version), if I wanted to start by just using key central locking and not remote locking, can I just unplug those two boxes?
This car is a Japanese import and had some electronics in it - old DVD-based GPS system and a TV terrestrial receiver, so probably a lot of RF floating around near the receivers. But that is all removed now.
Many thanks once again....

View attachment 247301

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The black boxes you are seeing in the doors are the outstations, the RF receiver is in the rear drivers side under the parcel shelf side panelwhere the seat fold down latch is,


these are the three original ones the good one is on the right and you can only really tell by taking them apart


heres a better picture

Ah, OK.
A quick check shows that the receiver is the original as per the left hand one in the 3-way image. I have removed it, central locking works fine and I shall await availability of MartyUK's high-tech "spurious-RF-proof" version.

You can put a remote jog switch in that will stop signals to the becm for about £10 but you have to to press the new fob before unlocking with the original. if you want more details i will post them up.

brianp38dse said:

You can put a remote jog switch in that will stop signals to the becm for about £10 but you have to to press the new fob before unlocking with the original. if you want more details i will post them up.

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Interesting - a fob that unlocks the link between the receiver and the BECM to stop any unwanted signals. However I think for the moment I'll just leave the receiver out and use key central locking, waiting for MartyUK to produce some more RF-proof units. I am an old git and sticking a key in a lock appeals to my desire for simple stuff...but thanks for the idea - might well revisit that in the future when things have settled down. If you don't mind posting the details I can store them for later...

Here you go my cheap work around

https://www.landyzone.co.uk/land-rover/rf-reciever-work-round.258096/

You could always pull the blue aerial wire and stand close to the driver's side rear window to use the remote, for the time being.I fitted a remote jog switch years ago, you soon get used to using two remotes and saves loads of money.

OK, so MartyUK's test showed that the passenger door latch CDL motor had failed. Probable cause RF overload. Got a good used latch from East Coast 4X4, tested it - OK. Removed the remote fob receiver, fitted the new latch. Central locking works fine now, and when MartyUK has some new style RF-proof receivers for sale, I'll go back to remote locking. Until then, sticking a key in the lock and securing all doors/boot at once is fine. Many thanks for the advice that got this job done - greatly appreciated.

brianp38dse said:

these are the three original ones the good one is on the right and you can only really tell by taking them apart

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Hi Brian, I have just been given one of the centre types in the picture (with the metal screen box thingy).
Looks like that is not the best one to use, and I don't want to burn out the motors.
Should I return it and wait for MartyUK's bomb-proof one? I am happy enough to continue using central locking...

P38 Monkey said:

Hi Brian, I have just been given one of the centre types in the picture (with the metal screen box thingy).
Looks like that is not the best one to use, and I don't want to burn out the motors.
Should I return it and wait for MartyUK's bomb-proof one? I am happy enough to continue using central locking...

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Check the part number. I have heard some of the newest have gone back to a single board.

I wouldn't put an old one on. It isn't worth the risk. My wireless weather station was scrambling mine.

Grrrrrr said:

Check the part number. I have heard some of the newest have gone back to a single board.
I wouldn't put an old one on. It isn't worth the risk. My wireless weather station was scrambling mine.

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Sound advice as ever. Actually, being an old git I like sticking a key in the lock. Central locking is as much of a luxury as I need. Thanks again, as ever.

What a marvellous invention central locking was all those years ago and it’s just getting harder to understand your car unlocks itself as you approach it now and parks itself in small spaces I dread to think what’s next