850 estate tailgate lock servo?
 

Hi All,

My 1995 850 T5 has decided that it doesn't want the tailgate to always lock/unlock with the central locking lately. I know there is a common issue on these where the wiring gets chaffed at the left hinge to the tailgate causing funny business with the rear wiper and lock. I don't think it's that though as I had that previously and fixed the wiring there by carefully soldering and re-water proofing it, and it's worked fine for 6 months or so. This time it seems related to the tailgate lock itself, I think. I took it to bits today to see what's what with reference to the Haynes book of lies...

This is the lock removed (rear panel removed first with some horrible brittle sharp clips):

https://farm5.staticflickr.com/4646/...d24ddde2_b.jpg

It seems to work well enough manually (i.e. if you put the key in the tailgate, and in fact locks / unlocks all other doors too which makes me think the electrics though the hinge are ok). I suspected a weak servo so took that off to have a look.

https://farm5.staticflickr.com/4733/...7de94d9c_b.jpg

It felt extremely weak in operation and when I got my wife to turn the key in the drivers door with it plugged but dangling from the open tailgate in I could see it would only move to lock, but not pop back up to unlock unless I helped it a bit by hand. Probably not fixable but I took it apart a bit more to see what's inside as I like dismantling things. Ooh, a little motor, worm gear, switch contacts etc. Note in this pic the white plastic part isn't aligned properly and one of the switch contacts on the yellow wire has popped out of place, I put it back later.

https://farm5.staticflickr.com/4738/...759ecc17_b.jpg


Everything seemed to move freely in there, and the lock mechanism itself was easy to operate by hand so I put it back together for now and will investigate a replacement servo if I can get hold of one. Has anyone else replaced one of these? I presume you can't get hold of the servo but need to replace the full lock with a secondhand one? Are they all the same, V70 P1 too?


Not sure what else could be at fault but any suggestions welcomed. In the meantime, central locking works everything but the boot reliably, that needs checking and use of the key to make sure which quickly becomes a chore. It probably locks one in ten times, and unlocks one in five maybe so does occasionally work.

On a related note, the handbook tells me I should be able to isolate the boot from the central locking by removing the key with it in a certain position (I forget which now), but that doesn't seem possible - any ideas?

Thanks
Stu

Just to update, I found a secondhand but listed as 'good working order' lock assembly to suit on eBay so that's on it's way. Hopefully that'll sort it, I will update with progress when it arrives and I try fitting it.

I also picked up a pair of new CR1220 batteries for the remote fob as I might as well fix that whilst I'm at it.

I finally had a day off today and it wasn't raining, so got chance to fit the replacement boot lock (inc. servo) I got from eBay a few weeks ago.

Replacement on left, old one on right:

https://farm5.staticflickr.com/4703/...6a20760f_c.jpg

https://farm5.staticflickr.com/4602/...47f9552b_c.jpg

I noticed the replacement one had a bigger VDO servo rather than 'Rockwell international' original, not sure it'll make much difference.

Anyway, stripped the original lock back out of the tailgate, dangled the new one on the wiring and locked/unlocked the car via key a few times - seems to work. Put it in place and connected up all the gubbins and I now have a car that central locks/unlocks all doors and the boot too again. To celebrate I fitted new batteries in the remote fob that I'd ordered so that works again now too. :thumbs_up:

Only other little job I did was to clean out the front door drain holes (can't find any on rears?) and scuttle panel drain tubes under the bonnet as the car has been holding moisture lately and steaming up a bit. Going to see if I can find any other water traps, does it have a pollen filter I wonder that could be clogged? Question for another thread probably.

This is a really excellent post Stu, thank you. I have also bought a second hand one, but it's not arrived yet unfortunately.

On your other point, my V70 also gets terribly condensated in the Winter. I spent a few hundred pounds getting the AC fixed (probably spent more than I could get if I sold the car), and now it clears the windscreen beautifully. It also does the driver and passenger windows, but not quite as well. I didn't know about the water drainage holes, so thanks for that, I look into it when I have time to spend on the car.

I'd heard somewhere that it might also mean that the heater core matrix needed replacing. That looks a big job in itself, do you think it could be the cause of the condensation?

Cheers
AL

No problem, Al - glad it's helpful. Hope your lock mechanism replacement goes to plan.

My 850 has AC (well, ECC or whatever it's called), that doesn't blow cold that I mean to get around to fixing at some point. In the meantime, my drain hole clearout the other week seems to have helped as the car hasn't been misting up anywhere near as much since. After I posted here, I had a lie on the floor and found drain holes at either end of all doors so stuck a cable tie up those to check they were clear and got some crud out of a few. The drain pipes from the scuttle panel are rubber down pipe type things that go down towards the bottom of the engine bay behind the front wheels, you can flush / rod those out too.

As regards the heater matrix, I don't think that's my issue as there is no coolant level drop or oily misting effect on the screen, I've had that before on numerous Mk2 Golfs as they commonly blow the matrix and either give your feet a scalding coolant bath whilst driving, or just fill the passenger footwell if you're lucky! :thumbs_up:

All the best, Stu

Great thread. I have a problem with my tailgate, 1999 V70, it won't operate and have ordered a 2nd hand replacement to take out to France (car now French reg). Had problem before and fixed it with WD40, tailgate panel refitted with screws rather than clip and as the t'gate doesn't have an interior/exterior handle (no 3rd row of seats) or key way, I fitted a wire coat hanger from the lock unit up and through the plastic panel at top of t'gate cover, to act as a pull/push knob im case it locked shut or wouldn't lock on central locking.

A solution - without buying a new lock assembly
 

I had a similar problem with my 850 Estate, the tailgate lock often failed to work with the doors. Sometimes it could be operated with the tailgate key - but sometimes that seemed too resistant to turn, as if something was jamming it. However, I could hear the tailgate lock servo whenever I operated the doors - it just didn't actually lock/unlock - from which I guessed I did not have a problem with wiring at the hinge.

To cut a long story short, the problem was a 'lack of power' from the small motor in the lock servo. The first photo shows the whole lock with the servo opened (a screwdriver and Stanley knife job!).
The next 2 photos show the servo fully open, and the failure with the opening incomplete. The motor has insufficient power to disengage the 'traveller' on the screw from the white operating lever (there are 2 spring-loaded detents).
The final 2 photos show the equivalent 'locked' positions, again showing how the servo fails to complete the operation and disengage the traveller. This failure to disengage the 'traveller' is the cause of the key 'jamming', as you simply can't turn it hard enough too disengage the white operating 'rod' from the 'traveller'.

At first sight, a new motor is required. However, it transpired that the problem was oxidation on the push-in electrical contacts on the wires where they connect into the motor. Simply cleaning them, and giving the motor commutator a dose of switch-cleaner, was enough to restore the motor to 'full power'. Now everything works again; long may it last!
By the way, I fixed the servo motor back using 2 M4 55mm long Pozi machine screws - and simply held the lid on by securing it with washers/nuts.

I spent sometime trying to track-down the motor. As far as I can ascertain it is a variant of the Mabuchi FC-280. However, so far I can't find the variant with the correct spindle - most of them come out the reverse end of the motor! The FC-280PC-SC is available with a 6mm long shaft, requiring an adaptor to be made. In the USA the FC-280-18180 is available with a knurled 9.5mm shaft (the correct length), but I can't source it in the UK.

I'm simply hoping at the moment that I won't actually ever need a new motor.
Volvo do still sell the complete lock assembly, part 9203375, at a mere £133.80p - but my repair cost practically nothing!

I hope this helps some others with this tailgate locking problem.