Yaris MK1 door lock mystery!

[Mertsi1340]

The car is a year 2000 model. It has central locking, but it works by turning the physical key in the front locks (no FOB). The door locks started acting up a few months ago. It would not randomly lock/unlock all the doors, but turning the key in the other front door lock would lock or unlock all the doors. And the next time I used the key to lock/unlock the doors, everything worked fine again.

Lately though, it has become worse and most of the time locking/unlocking the doors using driver's side lock would lock/unlock all doors except the passenger side front door. Or it only opens driver side doors (and the hatch door).

Locking/unlocking the doors using the passenger front door lock could open all the locks except for the driver side doors (only front or rear or both).

Very seldom, it locks/unlocks all doors.

Sometimes, for example locking the doors, I notice a slight movement in the other front door locking nob as if is it wants to lock, but locking does not happen 

So basically it acts very randomly, and I do not know how to start diagnosing this problem.

One thing about the front locks: It is sometimes very difficult to turn the key in the lock, but using a lubricant usually helps for a while until the next time the same problem arises.

I have used the second key, but the end result is the same.

I have also checked fuse No. 19 (25A) and it works.

Would be grateful if you point me in the right direction. 

[flash22]

Passenger side door solenoid and/or the latch is gummed up with old grease (turns to chewy toffee constancy) 23 year old Japanese grease does tend to do it

use a decent lube like GT85 and spray the snot out of the lock and latch, WD is a good degreaser but has little lubricating properties

[DerekHa]

Hi Mertsi,

From what your say it seems that the application of a lubricant eases the problems your having with opening/closing your Yaris doors. Wondering what your using to lubricate the locks? Most people will use something like WD40 or a similar penetrating oil, have used this myself in the past many times over the years and it would help with sticky locks and the mechanisms inside the door(s).

A few years ago I went to a locksmiths with a problem ingition/steering lock. I was advised that WD40 isn't ideal for use inside lock barrels, it's short lived and evaporates relatively quickly. They advised using a product called GT85, another good penetrating oil but also contains PTFE, when applied the penetrant does it's usual work but the PTFE remains and doesn't evaporate and continues to lubricate the interior of the lock, the barrel and tumblers inside.

At 23 years old the grease applied to the lock barrel(s) when manufactured will have dried out and I think this is likely to be the cause of your central locking problems as the symptoms sound to be very random but some lubrication helps for a while. It may pay to remove the door cards to better access the actual lock mechanisms and applying a GT85 like product to those hidden parts. Try not to get the product on your door glass or weather seals as it may make for smeared door glass afterwards.

Worth a try as it's relatively cheap and easy top apply.

[DerekHa]

5 minutes ago, flash22 said:

Passenger side door solenoid and/or the latch is gummed up with old grease (turns to chewy toffee constancy) 23 year old Japanese grease does tend to do it

use a decent lube like GT85 and spray the snot out of the lock and latch, WD is a good degreaser but has little lubricating properties

Seems Flash beat me to it with pretty much the same advise!

[Mertsi1340]

15 minutes ago, flash22 said:

Passenger side door solenoid and/or the latch is gummed up with old grease (turns to chewy toffee constancy) 23 year old Japanese grease does tend to do it

use a decent lube like GT85 and spray the snot out of the lock and latch, WD is a good degreaser but has little lubricating properties

Thanks for the speedy reply.
I have used WD-40 for lubrication purposes.

Do I use this new lube on top of the old one, or do I have to open/remove the lock and give it a good clean?

One of the properties of the lube should be its cold resistance properties, since here in Finland we could even have -30 °C to -40 °C temperatures (during winters of course 😄).

[flash22]

You can remove the latch if you want, yes it will just rinse the wd40 out of the way, not sure if GT85 is available in your market

Another good lube is Swarfega Duck oil

[Mertsi1340]

Progress report:

I cleaned both front locks using brake cleaner and then applied a Teflon lubricant to them. The nearby shops were out of lubricants with PTFE. But my understanding is that Teflon and PTFE are the same thing.

Now turning the key in either of the front door locks, locks/unlocks all the doors except the other front door. This is officially counted as progress but I can't figure out why the front doors do not communicate with each other?

Any suggestion is more than welcome.

Cheers

[bathtub tom]

How old is the Battery? They can throw up some curious symptoms when they get old.

[Mertsi1340]

33 minutes ago, bathtub tom said:

How old is the battery? They can throw up some curious symptoms when they get old.

The Battery is about 1 year old.

[flash22]

The door you open with the key mechanically opens the latch, what clicks a switch to activate the central locking

if you unlock it from the driver's side it sends a signal to the passenger side a vice versa, ergo, the passenger side has a bad solenoid check the plug and socket on the solenoid for corrosion - IIRC it has it own solenoid/actuator, as for parts it needs to come from a Japanese built yaris - but it looks like there are plenty of aftermarket ones from 15-20 euro

From the driver's seat

RH 69110-52010

LH 69120-52030

 

[lani100]

Faulty solenoid, common issue at this age

[Mertsi1340]

4 hours ago, flash22 said:

The door you open with the key mechanically opens the latch, what clicks a switch to activate the central locking

if you unlock it from the driver's side it sends a signal to the passenger side a vice versa, ergo, the passenger side has a bad solenoid check the plug and socket on the solenoid for corrosion - IIRC it has it own solenoid/actuator, as for parts it needs to come from a Japanese built yaris - but it looks like there are plenty of aftermarket ones from 15-20 euro

From the driver's seat

RH 69110-52010

LH 69120-52030

 

Thanks 

How do I know which door's selenoid is faulty? Or are they both faulty? I understood from your post that the passenger side selenoid is faulty but regardless of which front door lock I use, the other front door does not respond to the locking/unlocking action done on the other door.

Do those part numbers correspond to left hand drive cars.

Once again, thank you very much for your comments. I will try to check the connections first 

[flash22]

LH and RH doors it's not LHD or RHD (driver position) if it matters, I did look up the part with LHD as a parameter tho