MGTF Door Lock question

I definitely had a door rattle but not driven the car since fixing it earlier. Now I find that some old biddy visiting next door has scuffed my bumper! just 4 weeks after having it resprayed !

Not happy!

Sundance

Sundance ,
thanks for all your input on my query,
I still have a problem with my door lock so will need to get a replacement and look closer at the broken one..
thanks
Mike

For anyone who may find it useful, here is a scan of the MG-Rover drawing for the door lock, and followed buy a map of the pinout of the connectors for the lock unit ( as seen on the lock itself, not the wiring harness).
Look for a resistance of about 1 ohm on the switches (3 to 4 ohms with meter lead resistance) and between 17 and 30 ohms across the locking motors (I cant remember which was which).

Sundance

hello again,
you must have been reading my mind when you did this post, I was just about to get together all my notes and circuit stuff and revisit the central locking info with a view to putting together a bench test routine for the driverside door lock.

I have a few questions re your excellent diagrams.
1. which service manual version did you get your version of the locking mech internals, mine is from an MGF service manual.and the switching layout is different for some reason
2. the momentary switch between 1450/2 and 1449/2 ,where is it located ( since there are 3 microswithes inside a driverside lock mech ) is it one of them?
3.if NC is no connection? what is N/O ? sorry could be getting late for me!


to add ..

lock motor is usually around 4.5 ohms

superlock motor(smaller ) -my one i am checking is 52 ohm ( that could indicate a fault condition,dont know yet)

cheers
Mike

NC is normally closed and NO is normally open, if you look at the diagram, you can see the switch configuration.
I have not stripped the switch down, so not sure exactly how the swiches are laid out inside the unit, the info I had were taken from the bench test I did on mine when it was out of the vehicle. For instance, the signal for the locked switch on pin 3 changes state when you operate the mechanical latch simulating closing the door.
Although I have stated N/O and N/C for the lock switches, this is referenced from the drawings and I am not sure if this is in regards to the door open and unlocked or closed and locked. This would also be good to know.
It would be worth while, if stripping your lock down to see if there are any problems inside, to post up some pictures of the unit in pieces and what switch does exactly what and where inside it is situated.
I would certainly have done that if I had pulled mine to bits, but knowing how tricky they can be to put back together (been there and done that with my ZT) I was glad I did not have to.
The electrical schematics I have are the ones taken off this site in the download section, they were drafted or issued in August 2003 (about right for me, as my car was assembled in Dec 2003 and registered in 2004. So far I have done quite a bit on the electrics and not found any errors in the schematics and what is on my car.
I actually applaud the designers of the electrics on our cars as the schematics are easy to follow, well labelled and cross referenced. Probably the best auto electrical schematics I have ever used!
It does help being an industrial electrician and having electrical control system design experience though.
Good luck with the fault finding, and keep us up to date, maybe after you get this sorted and acquire more data, we could possibly write up a detailed how to for diagnosing and repairing these locks between us, even if its just a set of expected reading when certain switch are operated.

Sundance

Sundance,
I did find the actual 2003 TF manual last night so got the same diagrams as you have .
My background is electronics so not as good with electro -mechanics as you are.
Anyway I did take a lot of in internal photos a couple of years ago so hopefully here they are showing.
1. the lock motor and superlock solenoid and how they mate up with the actuators.
2 the superlock female plastic half is a weak spot where it fits in a spring.cup
3.there is a good view of the microswitch bank of 3 micorswitches and the 5 associated wires to them.,cant quite see what operates them but I do know they are a point of weakness mainly in that they move in there locating box.
When I took this unit apart I was looking for plastic cog damage but didn't find any ,just some displacement of the microswitch bank which i thought I had fixed but it has some problem on the switch between 1449/3 and 1450/1.
Any comments appreciated
mike

Fine work, Mike, posting these up gives us a good idea of whats inside, the switch bank looks quite robust and really, the lock motor should work forever and a day, its just the plastic gears and sliders, work of the devil!
I think I found in mine that the root cause of the issue was the worn plastic bush in the key barrel lever, stopping one of the rods to pull the switch properly, hence the machine gun rattle of the locking motor.
This may be a common problem and would be the first thing I will now check with a faulty locking unit.

Sundance

Great detail in those photos Mike but I now know where you live.......

Lol.
I'm the other side of Stoke, Mike - in Alton

Sundance

Sundance and Talking Cars

thanks for your interest , I have not replied since last time as I have been doing more investigations on another driver side door lock.
there are 2 points to add ... the main failure point with respect to the super locking is

1. the super lock motor is the failure area -it moves over time in its mount ( mechanical stress probably ) and disconnects the printed circuit wiring between the feedwire and its own solder points ( this causes the high resistance reading across the motor )

I agree that the main motor itself very robust . .

Any failure in the main motor area seems to be associated with the lower microswitch in the 3 way bank , the head ( tip) of the microswitch seems to get flipped off over time and causes a permanent open in that switch (no feedback to the SCU or BCU in earlier models.
The long lower plastic arm operates the bottom microswitch and is moved by the action of the door lock motor being closed or opened by the fob ( takes about 3 amps to operate this motor by the way but it is a beefy motor unlike the superlock motor)

looking for a solution to this problem ( i am sure that there was someone on this forum that knew where the microswitches could be obtained from)

Mike

I still know where you live - the address is in your photos!

yes -not very secure ?

Mike