[voxmagna]

There have been several posts about the trunk lid lock so I thought I would put up an explanation of how it works on MY07 TDi. Normal operation of the trunk lock is important for the roof to work. The roof system uses the open/closed lock switch as feedback.

The lid lock is in 2 parts and without removing trim or covers, it can be hard to figure out what's going on. Both parts have mechanical and electrical operation. Understanding how the lock works is essential if power or control is lost.

The trunk lid contains the business end of the lock. As you look into an open lid you can see the fork and an internal rotating 'V' claw. This assembly has a three wire connection. The lock is locked mechanically without power. As you close the lid, the claw engages with the roller pillar you see in the second bottom part of the lock which I will call the 'keep' and pushes the rotating claw around where a spring then holds it in the closed or lock position. This rotating 'V' claw is free moving, you can close it very easily with a screwdriver and then not be able to shut the lid! This is what can happen if the claw gets closed and is 'out of sync'. No electrical power is required to close the claw! The claw is only released by electrical power to a motor which releases a mechanical latch and the claw then rotates open, allowing the lid to pull out of the keep. That's why the EOS cannot close its lid from the console. It can only close the lid during roof operation using hydraulic rams. Two wires in this upper lock assembly are used to power the release latch and a third wire is a signal wire to determine if the 'V' claw is open or closed. The assembly has a crappy length of plastic (the square you can see underneath on the right). When pushed up, this mechanically releases the lock latch to open the claw.

The second part of the lock is the 'keep' which isn't just the simple bar you can see. The keep bar can be moved down and up by a motor - the 'whirring' sound you hear as the trunk lid is closed or opened. IT HAS NOTHING TO DO WITH THE ACTUAL LOCKING. Its purpose is to pull down the trunk lid on to the two black sprung buffer stops and to compress the trunk lid into its seal.

This is the sequence for locking: As the trunk lid is lowered when the keep bar is at its highest point, it slides into the slot and the 'V' claw rotates to the locked position. The locked closed switch then activates the pull down motor and the keep bar drops until limit or over current and stops. The trunk lid is now compressed on to its seals and hopefully no water gets in!

The trunk lid can only be opened in two ways - electronically or mechanically. The normal electronic open sequence is to activate the lid motor to release the locked claw causing the lid to pop up from pressure on the seal, then the keep bar is lifted (whirrs) to the high position ready to receive the lid when it is next closed. The flip up VW badge does no more than operate a switch. If there is a power or control problem, it won't release the lock.

Ignoring the tensioning feature, the locking and unlocking is purely mechanical with electronic motor assistance only for unlocking. An emergency cable with red pull ring is run to just behind the ski panel which opens the lock if there is a total power fail or control problems. This is where something as important as emergency release design went a bit wrong. The best place to operate the release is actually in the business end of the lock in the trunk lid. However, in VW's scheme of things, they ran their emergency release wire to a lever on the right of the keep assembly mounted on the fixed rear panel. They then used a crappy plastic conecting rod in the lid assembly, which ends as the small square you see to the right of the claw. Therefore, their emergency trunk release relies upon the cable working, the push up lever on the back panel working and not getting misaligned and their short flimsy plastic push rod not breaking or its location peg falling out.

Everybody with an EOS should occasionally remove the ski panel with the trunk lid closed, pull the emergency trunk release and make sure it works!!
.

 

[FSJ Guy]

Excellent explanation!! Thank you!

 

[Batjes]

Thanks, this makes the workings of very clear and I'll need that when my trunk gets a mind of its own.

 

[Knaptryk]

I agree - great explanation of how things work.
Now I just have to find out why the closing aid (is that the proper name?) does NOT work on mine...

 

[voxmagna]

The closing aid or tensioning motor is an electric motor which you can test with an ohmeter. It is probably 12 volts and you could tap a couple of wires on to the nearest connector with a 12 volt led or the voltmeter on a long wire where you can see it. If the led is operating and the motor shows low resistance, you are probably looking for something mechanical which stops the motor working and pulling down the bar. If the led isn't working look for a control module or wiring fault.

 

[gsohara]

Useful thread... I can see now the reason my boot doesn't lock is the keep bar is in the down position. Is there a way of forcing it up safely?

 

[voxmagna]

As I explained, the 'keep bar' is moved up and down by the motor to pull the lid on to the seal. That is the motor whirring noise you hear after a normal trunk lock or unlock. Sounds like you could have a fault or something mechanical wrong inside the lock mechanism? Diagnostics will tell you if there is an electrical control problem. Otherwise, you will have to remove the lock assembly with keep and look for a problem inside stopping the motor from moving, assuming the motor is being activated?

 

[Minimia]

First post on here, so tip of the hat to you all.
I’ve been struggling with (you’ll never guess!) a leaky roof problem, and today went to do the whole Krytox procedure. And my roof wouldn’t open. Moon roof slides back, then it all stops and it throws ‘system error’.
So, why am I posting this on a thread about rear deck locks?
Well, I’ve noticed that recently, I’ve had to give my rear deck a real slam when I close it. The ‘soft close’ thing doesn’t seem to be working. I’m wondering whether the 2 things could be linked. Maybe the source of the roof problem is the rear deck lock. Is this remotely plausible?

Edit, and of course, if I’d searched properly for ‘rear deck lock failures’, rather than just ‘roof problems’, then Ikdnhave seen that this is a relatively common reason for roof failures, and totally plausible. Sorry guys.

 

[nexus6634]

Hi Voxmagna

I know this thread is a little old but you seem to be the person to ask!

Roof won't open, I get an error message 'close boot lid'.
I have traced this to the boot not power closing when I shut it.

I removed the bottom part and checked the motor with 12v power, which works fine and pulls the keep bar down.

I then removed the top lock and found a corroded terminal (the one connected to the small silver bar and red button) which sends a signal to the bottom motor to tell it to pull the keep bar down. I fitted a brand new top lock but still no joy.

Top lock appears to be working correctly, bottom lock with keep bar seems to be working correctly, I can only assume that the corroded terminal has blown a fuse somewhere??

I checked the 7.5a fuse in the side panel where you open the drivers door and thats fine too. Is there another fuse that would be blown??

Any help you can offer would be appreciated. Thanks in advance!

Paul

 

[voxmagna]

Does the luggage compartment light come on when the lid is open? Check the common ground connections (brown) do actually go to ground (battery -ve) at the common earth point on left in luggage compartment.

Some of the wiring (e.g trunk flap release) must get flexed about as the trunk lid opens and closes. Trace each wire back to the hinge (and beyond) where they fasten the wiring and check there are no breaks. Also check the pins, wiring and terminals on the black 5 pin connector in the rear lid. I get the wires warm with a hair dryer and stick pins in to check continuity. Some of the roof wiring is attached to the left side roof hinge itself and is flexed during roof ops. V.W use really skimpy wire and unlike a braided wire, can look ok outside but be broken inside. With each wire warmed with a hair dryer, I test it by trying to stretch a length. If the outer pvc jacket stretches like a sausage, it was broken.

The trunk lock is powered from the convenience control module so I'm not sure what fuse you looked at?

Diagnostics will tell you if there is an electrical control problem.

- In the convenience module.

 

[hobbsrp]

Boot Lid Lock quick fix?

There have been several posts about the trunk lid lock so I thought I would put up an explanation of how it works on MY07 TDi. Normal operation of the trunk lock is important for the roof to work. The roof system uses the open/closed lock switch as feedback.

The lid lock is in 2 parts and without removing trim or covers, it can be hard to figure out what's going on. Both parts have mechanical and electrical operation. Understanding how the lock works is essential if power or control is lost.

The trunk lid contains the business end of the lock. As you look into an open lid you can see the fork and an internal rotating 'V' claw. This assembly has a three wire connection. The lock is locked mechanically without power. As you close the lid, the claw engages with the roller pillar you see in the second bottom part of the lock which I will call the 'keep' and pushes the rotating claw around where a spring then holds it in the closed or lock position. This rotating 'V' claw is free moving, you can close it very easily with a screwdriver and then not be able to shut the lid! This is what can happen if the claw gets closed and is 'out of sync'. No electrical power is required to close the claw! The claw is only released by electrical power to a motor which releases a mechanical latch and the claw then rotates open, allowing the lid to pull out of the keep. That's why the EOS cannot close its lid from the console. It can only close the lid during roof operation using hydraulic rams. Two wires in this upper lock assembly are used to power the release latch and a third wire is a signal wire to determine if the 'V' claw is open or closed. The assembly has a crappy length of plastic (the square you can see underneath on the right). When pushed up, this mechanically releases the lock latch to open the claw.

The second part of the lock is the 'keep' which isn't just the simple bar you can see. The keep bar can be moved down and up by a motor - the 'whirring' sound you hear as the trunk lid is closed or opened. IT HAS NOTHING TO DO WITH THE ACTUAL LOCKING. Its purpose is to pull down the trunk lid on to the two black sprung buffer stops and to compress the trunk lid into its seal.

This is the sequence for locking: As the trunk lid is lowered when the keep bar is at its highest point, it slides into the slot and the 'V' claw rotates to the locked position. The locked closed switch then activates the pull down motor and the keep bar drops until limit or over current and stops. The trunk lid is now compressed on to its seals and hopefully no water gets in!

The trunk lid can only be opened in two ways - electronically or mechanically. The normal electronic open sequence is to activate the lid motor to release the locked claw causing the lid to pop up from pressure on the seal, then the keep bar is lifted (whirrs) to the high position ready to receive the lid when it is next closed. The flip up VW badge does no more than operate a switch. If there is a power or control problem, it won't release the lock.

Ignoring the tensioning feature, the locking and unlocking is purely mechanical with electronic motor assistance only for unlocking. An emergency cable with red pull ring is run to just behind the ski panel which opens the lock if there is a total power fail or control problems. This is where something as important as emergency release design went a bit wrong. The best place to operate the release is actually in the business end of the lock in the trunk lid. However, in VW's scheme of things, they ran their emergency release wire to a lever on the right of the keep assembly mounted on the fixed rear panel. They then used a crappy plastic conecting rod in the lid assembly, which ends as the small square you see to the right of the claw. Therefore, their emergency trunk release relies upon the cable working, the push up lever on the back panel working and not getting misaligned and their short flimsy plastic push rod not breaking or its location peg falling out.

Everybody with an EOS should occasionally remove the ski panel with the trunk lid closed, pull the emergency trunk release and make sure it works!!
.

Thanks for the excellent description of how it works.
For what it's worth, mine was not pulling down on the electric motor but could be slamed fully shut without the motor noise. Armed with the description above, I noticed the "keep" was not rising up smoothly as the lid was open and therefore, I'm guessing, was staying down - hence was not engaging properly when closed.
Armed with a can of lithium grease and some careful application, it has all started to work again! Whether it continues to work or if it will need further investigation only time will tell.

 

[voxmagna]

At least you got a solution of sorts. I tend to go further inside because it's the last thing you want going wrong with a trunk full of expensive gear and miles from home. A bad trunk lock also stops the roof working.

Lithium grease is great stuff, but locks and their mechanisms tend to be designed with large tolerances so they don't need it, or just a minimal amount in the right places. Shooting in more grease can attract dirt and gum things up some more. Anyway, if it's working for now you put it on the 'to do list' for good weather or the next seal lubrication.

 

[LostMyEOS]

Long story, short. The trunk used to open but the top did not work and it is stowed in the trunk. The dealer tried to override the codes to make it move, so the C (or V) latches rotated and now not even the trunk opens. Cannot access the mechanism from the ski door to release them. Is there any way to release those latches through the flaps where part of the top is stored behind the door? Or is there any other way to get to them without cutting the trunk? Running out of options and any thoughts would be appreciated. Thanks.

 

[voxmagna]

This is an unfortunate situation that can arise, particularly if the roof controller is faulty or has stopped and locked out mid cycle. I have already posted 'Get out of Jail' modifications once you have got the trunk lid open because after struggling for a couple of days, it's something you never want to happen again.

Is there any way to release those latches through the flaps where part of the top is stored behind the door?

There is a single hydraulic ram on each side of the parcel shelf/trunk lid hinge which closes the roof locks and opens the trunk lid 'C' claws. Normally those rams are enclosed in plastic trim covers. If both side flaps were forced open (and damaged?) I don't know if something like a longish wooden dowel rod could align with the end of the ram which would need to be pushed fully closed with some force? IMHO quite a lot of push force is needed to get all the roof 'C' claw locks to roll over their keeps. It surprises me when the shop manual says open the pump emergency valve (Trunk lid is open) and push them fully forwards to release the roof locks to close a stuck open roof, because considerable force is needed?

The trunk lid is locked down in 2 ways and the emergency pull wire won't help you. The 'C' claws in each corner of the lid are locked because the roof is in its unlocked situation and the car really isn't safe to drive. You cannot access the hydraulic rams to push them in to both lock the roof and unlock the 'C' Claws and neither can you open the pump release valve.

Dealing with the 'C' claws first you have to try various rods and poles with a strong hook or wire loop through the ski hole and try to pull them back. But they are spring loaded so tension needs to be kept on both claws. They rotate around the chrome hoops with upwards or downwards tension and the best place to get pulling effort is on the tip of each 'C' claw, but a catchpole wire loop tends to roll back and the effort isn't in the right place to rotate it over the hoop. I drilled a small hole in the ends of my trunk 'C' claws after getting the lid open.

The second problem is the center trunk lock. It won't release on the emergency pull wire unless the pull down motor is activated to set the lid in the fully lowered position. The pulldown is always in the raised position during a roof operation and only releases at the last stage when the locks are put on the roof parts and simultaneously removed from the trunk lid by hydraulics. An unfortunate complication is the pulldown signal only comes from a working roof controller and may not be accessible from a diagnostics computer if the roof controller is faulty. I've added a couple of wires to my pulldown motor connector so I can raise or lower it from the ski hole using a small battery to provide the signal. I think it may be possible to electronically operate the lock from a convenience module plug which is accessible from behind behind the glove box, but I've not yet tried it. I will probably fit a small emergency switch inside the glove box to do this.

Once the lid is open for fault finding and any future fault finding, I now remove the 2 chrome hoops either side of the trunk lid and put a pin through the top lock unit through a hole I drilled in the plastic cover. This stops the lock rolling over the keep roller and engaging if the trunk lid is closed.

Sorry, but AFIK you can only apply some creative solutions to this problem which can be very frustrating and take a lot of time. A faster solution is to use a strong flashlight in the trunk and 'A little person', but I don't think that's a recommended V.W service tool!

This is your first post and there is plenty here to read if you use the Search.

 

[serhat]

I recently had that problem.ı found out that 19 is the fuse for boot locking mechanism.



QUOTE="voxmagna, post: 160778, member: 2651"]
There have been several posts about the trunk lid lock so I thought I would put up an explanation of how it works on MY07 TDi. Normal operation of the trunk lock is important for the roof to work. The roof system uses the open/closed lock switch as feedback.

The lid lock is in 2 parts and without removing trim or covers, it can be hard to figure out what's going on. Both parts have mechanical and electrical operation. Understanding how the lock works is essential if power or control is lost.

The trunk lid contains the business end of the lock. As you look into an open lid you can see the fork and an internal rotating 'V' claw. This assembly has a three wire connection. The lock is locked mechanically without power. As you close the lid, the claw engages with the roller pillar you see in the second bottom part of the lock which I will call the 'keep' and pushes the rotating claw around where a spring then holds it in the closed or lock position. This rotating 'V' claw is free moving, you can close it very easily with a screwdriver and then not be able to shut the lid! This is what can happen if the claw gets closed and is 'out of sync'. No electrical power is required to close the claw! The claw is only released by electrical power to a motor which releases a mechanical latch and the claw then rotates open, allowing the lid to pull out of the keep. That's why the EOS cannot close its lid from the console. It can only close the lid during roof operation using hydraulic rams. Two wires in this upper lock assembly are used to power the release latch and a third wire is a signal wire to determine if the 'V' claw is open or closed. The assembly has a crappy length of plastic (the square you can see underneath on the right). When pushed up, this mechanically releases the lock latch to open the claw.

The second part of the lock is the 'keep' which isn't just the simple bar you can see. The keep bar can be moved down and up by a motor - the 'whirring' sound you hear as the trunk lid is closed or opened. IT HAS NOTHING TO DO WITH THE ACTUAL LOCKING. Its purpose is to pull down the trunk lid on to the two black sprung buffer stops and to compress the trunk lid into its seal.

This is the sequence for locking: As the trunk lid is lowered when the keep bar is at its highest point, it slides into the slot and the 'V' claw rotates to the locked position. The locked closed switch then activates the pull down motor and the keep bar drops until limit or over current and stops. The trunk lid is now compressed on to its seals and hopefully no water gets in!

The trunk lid can only be opened in two ways - electronically or mechanically. The normal electronic open sequence is to activate the lid motor to release the locked claw causing the lid to pop up from pressure on the seal, then the keep bar is lifted (whirrs) to the high position ready to receive the lid when it is next closed. The flip up VW badge does no more than operate a switch. If there is a power or control problem, it won't release the lock.

Ignoring the tensioning feature, the locking and unlocking is purely mechanical with electronic motor assistance only for unlocking. An emergency cable with red pull ring is run to just behind the ski panel which opens the lock if there is a total power fail or control problems. This is where something as important as emergency release design went a bit wrong. The best place to operate the release is actually in the business end of the lock in the trunk lid. However, in VW's scheme of things, they ran their emergency release wire to a lever on the right of the keep assembly mounted on the fixed rear panel. They then used a crappy plastic conecting rod in the lid assembly, which ends as the small square you see to the right of the claw. Therefore, their emergency trunk release relies upon the cable working, the push up lever on the back panel working and not getting misaligned and their short flimsy plastic push rod not breaking or its location peg falling out.

Everybody with an EOS should occasionally remove the ski panel with the trunk lid closed, pull the emergency trunk release and make sure it works!!
.
[/QUOTE]

 

[voxmagna]

Everybody with an EOS should occasionally remove the ski panel with the trunk lid closed, pull the emergency trunk release and make sure it works!!

I've been meaning to update this to add the emergency release doesn't work when the bottom lock keep is in the raised position (gap at bottom of lid).

A fuse usually fails because there's a fault. Even if the lock fuse is good, it won't help if the control signals coming from the roof control module aren't getting to the lifter control unit or the lifter control unit is faulty.