I recenly started getting the intermittent locking problem on one of my rear doors, caused by a failing door lock actuator. Having replaced one on my D3 about 4 years ago I'm familiar with the method of removing the lock mechanism, which is covered in the following posts...
www.disco3.co.uk/forum/topic33743.html www.disco3.co.uk/forum/topic101872.html http://www.disco3.co.uk/wiki/Rear_Door_Latch_Replacement
It's not too difficult to get the latch out once you know how, but re-fitting can be a bit fiddly, especially trying to relatch the external release cable. Patience and lots of swearing helps!
Anyway, having read a few posts on other forums (mostly Toyota/Lexus) about door lock actuator motor repair, I thought it would be worth looking into repair of my failing latch rather than paying £80 - £120 for a whole new unit.
The latch is basically 2 parts, held together with a couple of Torx screws - the part where the cable plugs in houses the 2 motors (lock and deadlock), and the other part contains the door latch mechanism, part of which you can see when the door is open. This picture shows the model fitted to mine, which has an additional motor for passive entry (on the right, next to the smaller connector socket)
This is my faulty latch removed from the door, with the internal release cable still attached (this need to be removed). The 2 silver Torx screw heads seen in this picture secure the 2 parts of the latch together. It's worth removing the small round spring (seen in the top of the picture) at this stage, otherwise it might fly off when the lock motor cover is removed later.
Click image to enlarge
Removing the 2 screws and carefully separating the 2 parts (latch mech on the right, motor locks on the left).....
Click image to enlarge
I've also removed the cover from the latch part in this picture, revealing the additional motor that I think is for the passive entry system. No need to strip this part down any further! The 4 smaller Torx screws have also been removed from the lock part, almost allowing the cover to be removed.
You can see in the following picture a white lever which I think tells the vehicle when the latch is closed fully (it's connected to a microswitch), but I couldn't work out how to remove it. It needs to come off to allow the lock motors to be revealed, and looks like the 3 plastic clips inside the white part should just squeeze together to release it, but it seemed too tight so I decided to leave it in place and cut away part of the black plastic cover instead, using a hot stanley knife.
Click image to enlarge
Once you've trimmed enough plastic away to remove the top cover, finally you get to the lock motors
Click image to enlarge
So there's 2 motors in there - the larger one with the brass gear wheel is the lock drive motor, and the small one is for deadlocking.
Carefully lift off the deadlock linkage (it's not really attached to anything) to access both motors..
and you can now simply lift out the lock motor, which is electrically connected by 2 'prongs' attached to the case (no desoldering or anything else required, it just pulls away from the case)
Click image to enlarge
Now to look inside the motor. To open it up, get a small screwdriver and bend the 2 small metal tabs up away from the plastic part - they may partly snap off but it doesn't really matter as there will be enough tab left to bend back down later anyway.
The brushes and commutator are covered in dirt and grease, which won't be helping it run well, so a good clean using white spirit and a small paint brush.....
Click image to enlarge
Be careful not to loose the tiny plastic washer mounted on the shaft next to the commutator - it pulls off but needs to go back on again!
Reassemble the motor, and test if you've got a suitable power supply - a 9V battery will be fine just to check it runs OK. I used 12V and it spins great - much faster than before it was cleaned up.
A few words on the spec of the motor - stamped on the case was Johnson Motor, which I Googled and found this page... http://www.johnsonmotor.com/en/features/ge...-lock.html but I've not found a source for Johnson Motors in low volumes. However, the Toyota forum mentioned Mabuchi Motor, who make an identical motor under the part code FC-280SC-20150 (web pdf http://www.mabuchi-motor.co.jp/cgi-bin/cat...fc_280pcsc) but it needs the longer 20mm shaft. Search eBay for '20mm Mabuchi Motor Toyota' and you'll find a few I've ordered one from Hong Kong to compare, but the dimensions are exactly the same as the motor fitted to the D3 & D4 locks, so it should be a perfect replacement. The only question is how to remove the brass gear from the old motor, and press it onto the new one? Unless the brushes are completely shot, it's probably unlilely that you'll need to replace the motor though.
Back to the reassembly....
Motor in 1 piece again:
Click image to enlarge
Motors back in place, with the deadlock link in place and a bit of extra grease for luck
Click image to enlarge
It's probably a good idea to make sure the deadlock link (the white plastic thing sitting on top of the larger motor) is in the unlocked position (as shown) for re-assembly otherwise the lock motor might try to work against it the first time you test it on the vehicle.
Now you need to re-assemble all the bits! It goes back together quite easily, but you need to make sure the white lever that sticks out of the lock motor part fits into a white plastic cup on the latch section.....
This lever
fits in this cup
Remember to re-fit the round spring to the plastic lever, and it should look like this once all back together...
Click image to enlarge
And now the fun of fitting it back in the door begins
I plugged it into the door loom before fitting, to make sure it worked properly. Now it's as good as new - locking and unlocking fully, every time 8)Previously:
2005 D3 2.7 TDV6 S
1984 90 2.25 Petrol CSW
1992 90 200TDi Hard Top
1995 Discovery ES 300TDi
2003 90 TD5 Truck Cab
5th Apr 2014 12:08 pm
Robbie
Member Since: 05 Feb 2006
Location: ¯\_(ツ)_/¯
Posts: 17932
Some real Sylar skills there.
Land Rover - Turning Drivers into Mechanics Since 1948
I had to Google that! Previously:
2005 D3 2.7 TDV6 S
1984 90 2.25 Petrol CSW
1992 90 200TDi Hard Top
1995 Discovery ES 300TDi
2003 90 TD5 Truck Cab
5th Apr 2014 8:23 pm
Biffysun
Member Since: 09 Jul 2011
Location: Central
Posts: 1790
Top Job!
5th Apr 2014 9:23 pm
NickJ
Member Since: 11 Oct 2010
Location: there's no f in point
Posts: 2137
Using ridgeback_moor's guide above, today I had to gain access to and strip down my driver's door as it was intermittently not locking. I found a way to remove the white plastic lever so that the two halves could be separated; there is a three-pronged pivot that the prongs need to be closed together, so I wondered if a cylinder would work. Looking around the garage I came across a roll pin that was not quite big enough so enlarged it by hammering it onto a pozi screwdriver
lever removed:
Click image to enlarge
using this by lightly hammering down onto the splines:
Click image to enlarge
Then once everything was done and back together, clearing up the workbench I found this brass tube which would have worked a dream :
Click image to enlarge
Once the motor was out and apart i've never seen so much crud:
Click image to enlarge
cotton buds used to clean:
Click image to enlarge
no wonder the door was intermittently not locking...
If anyone needs any assistance when they do this job, just ask. Done it once now...
26th Jul 2014 6:40 pm
Maxarn58
Member Since: 24 Dec 2011
Location: Sollentuna, north of Stockholm
Posts: 225
Thank You for a very good Tutorial.
I have had the problem with a faulty lock on the
passenger side (front right), the lock tab doesn´t
go all the way, so when I lock the car, passenger door
is still unlocked.
But not anymore!!!
Followed the step by step description, my lock
was not exactly like the one in the picture, but close enough.
So now, about 2½ hours later, I have four fully functional locks
on my car.
Thank You guys for a very good forum!!!
Rgds
UffeRRS MY2006 HST
As a rule, I always resist temptations,
unless they are irresistible!!
17th Oct 2014 5:17 pm
disco5
Member Since: 23 Dec 2012
Location: birmingham
Posts: 1088
Thats gave me something to do next
17th Oct 2014 8:58 pm
M3DPO
Member Since: 22 Sep 2010
Location: Notts.
Posts: 8227
Or for £2.65 you can keep one off these for a spare ready for next time.
Member Since: 11 Oct 2010
Location: there's no f in point
Posts: 2137
How do you get the worm drive thingy off the end of the old motor and onto the shaft of this new one?
18th Oct 2014 5:32 am
M3DPO
Member Since: 22 Sep 2010
Location: Notts.
Posts: 8227
They just pull off, heat it up and push it on the new one.It can when others can't,
It will when others won't,
It goes where others don't.
18th Oct 2014 8:13 am
MW
Member Since: 08 Dec 2005
Location: Huntingdon
Posts: 35
Stripped down a D4 door twice now to fix the motors. The door motor bible was excellent as ever on this site.
However, the 2nd time I took off the door handle as my sanity may have wavered trying to fiddle the cable back in again. I found taking the door handle off a far better solution and also made sure the fiddly cable was back in place correctly.
To take the door handle off. Remove the plastic bit to the side of the main handle, be very careful as the tabs are brittle. Top and bottom tab first and then ease out from the nearest part to the handle. Pulling out square will snap off the tab furthest away from the handle.
Remove the screw. Then remove the screw on the inside, access is gained from inside the door via the grommet hole for the door lock cable.
Now the plastic bit is removed the door handle will pull out and ease to torwards where the last plastic cap was. It will then come fully out and open right out. There is a cable on the far end on the keyless go so be careful.
Once this has come away ease the small plastic plug shown on the picture below. This then allows the internal assembly to slide and come away.
Undo the three Torx bolts for the main latch bit with all the motors and it all comes away.
It will all then come out.
Reverse to fit.
Just be gentle as ever with the plastic bits being external they seem even more brittle than internal bits even though hidden from the UV.
Hope this helps someone with massive hands !!
(cant figure out to attach pics to post so please look in my gallery for a couple of pics I took)
16th Nov 2014 7:22 pm
Mr.Fnoe
Member Since: 06 Sep 2014
Location: Remscheid
Posts: 1
Sorry for my bad english!
I had the same problem I have found a DC-Motor JOHNSON NF243G-993647062
You can use the part with the carbon brushes.
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I've ordered one from Hong Kong to compare, but the dimensions are exactly the same as the motor fitted to the D3 & D4 locks, so it should be a perfect replacement. The only question is how to remove the brass gear from the old motor, and press it onto the new one? Unless the brushes are completely shot, it's probably unlilely that you'll need to replace the motor though.
Top Job! 
:
