Boot latch for you Brits...

My trunk will not release electrically. The motor runs and the lid loosens but still cannot be raised. I have to use the key to finish unlatching it. It closes and pulls down normally.

I'd read in here somewhere that it needs some upward pressure to fully release, and weak struts will possibly keep it from unlatching, but my struts are OK, the lid stays up in even a stiff wind. Also, I can be lifting the trunk lid firmly when I press the button, it won't open.

I put this up on YouTube showing the behavior of the latch, how it only partially releases electrically.

 

Yes you need a new latch and they are expensive because they have a limited life.

Obviously used ones will have an even shorter life.

One of mine failed because a plastic cog broke and another failed over

a period of time because of a weak spring.

 

Yeah, for close to or over $300 I'll just continue to use the key. Electric operation is not that important to me.

 

I got mine for about $260.00 from ebay, or can get and OEM from https://www.oemvehicleparts.com/oem-...-latch-c2c1740 for $243.57 not including shipping. good luck

 

Mine acted the same. No amount of adjustment or total disassembly and inspection would make it work properly. Bit the bullet and bought a used one on Ebay for 130 bucks. Been working fine for 3yrs. Although I only use this car 5 mos a year.

 

Will the latch switch close the trunk or do you have to manually close it.

 

Closes properly. Button on trunk, dash, or remote releases partially, but not far enough to open. If you push the trunk down at that point, motor tightens it down correctly.

It's not really worth 250-300 bucks for it to not require the key. If it actually fails to latch, then we'll look into replacement.

 

OK. By your description the trunk should open from the remote IF you were to trying to lift the lid by hand at the same time. If that is correct, you may only need new struts to apply more upward pressure.

 

Nope. Lifting firmly while pushing the button, won't open, as stated in post #1.

 

When my lock quit I was unable to lock the car with the remote and forced to use the key. It would beep and always had the "boot open" displayed on the dash. Also the trunk lid did not appear to be pulled down tight and I was always concerned someone would try and pry it open thinking it would easy because the trunk lid could move up and down slightly. I purchased a new one on EBay for just under $250.00 in 2019.

The replacement latches are not very difficult to install with only two issues I experienced. The hard plastic surround cover is a little difficult to remove as it fits tightly near the outside portion around the latch mechanism. After popping the plastic "buttons" off with a forked auto body trim removal tool, I used a 1 inch putty knife to pop it away and drop the cover over the latch as it snaps tightly to the metal under a slight retaining edge.. Also, the hand protector insert cups in the trunk lid that are used as pull downs, (located on each side of the lid cover) are released by pushing inward on the sides of the plastic cups. The putty knife will work for those also. I thought they just need a little force to pop free and broke broke both tabs off of the first one I removed because I pried.it from the forward portion of the cup.. There were not any photos that I could find when I finally replaced my latch.

I used the key for several months as I did not want to spend the money. It got really old using my key to lock my car and to open the trunk on my Jaguar when my son could use his remote on his 2001 Taurus. Made me feel cheap (which I guess I was.) To top it all off so much time passed I forgot how to use the remote to lock the car. The lock button has worn down on the remote I use all the time and I kept pushing the lock button thinking the one button both locked and unlocked the trunk (like my son's car). I must have taken my trunk lid/latch apart 4 times and checked every ground I could find it the trunk area until my son checked it with the extra remote he has and asked me what my problem was. I just needed to order a new button pad. Just ask if you need any advice or have any problems changing it, should you decide to.

 

That issue will happen if the motor is dead and it can't pull the trunk lid down. Mine does that, it just doesn't fully release it when I use the button to open the trunk. It lifts up to that point you describe, but I need the key to finish opening it.

My motor works, there's something mechanical jamming the full release of the latch. In my video you can see the position the latch takes when I push the button. Yours was in that position when you closed the trunk lid, as the motor would not run to pull it down the rest of the way. When I manually closed the latch in the video, you hear the motor run, but only when it's pushed down from the fully open position. Yours wouldn't even do that. And yeah, with the trunk lid not fully down, the remote will not lock the car; the remote won't lock if anything's open, and in that position, the trunk is "open."

Curious about one thing... did you get water in the trunk during that stage? I'm wondering of the weather seal around the lid sealed well enough for you.

 

As my latch quit in the first part of summer I did not subject it to rain or a car wash. Hand washing did not show any leakage into the trunk. I first suspected an electrical issue to be the cause of it failure since my air suspension had failed and it took me a full day to replace the rear shocks. I was concerned that I had the lid open and was messing around for some time pushing things around installing the rear shocks. The trunk latch had worked fine until it was open with me crawling in and out. It would make a short cycling sound when I tried to open it but failed to release. It had worked fine the prior day when I swapped the front shocks as I disconnected the battery then reconnected it for the night. The last time it released the latch was when I was disconnecting the battery to do the last shocks and install the Arnott bypass module under the rear seat.

I fully intended to take it apart to see how it functioned but a quick examination showed me it was beyond my ability to take apart and then put back together..

 

2007 XJ8 L
trunk lock p/n’s
C2C1740
2W93F43200AD

youtube link

I am going to call the part that you can see when you have the trunk open the “lock latch”.
Theres another teardrop shaped part inside that has a electrical bridge attached to it along with a bearing type concentric in the center of the teardrop. There is also a nub mounted to the outside of the bearing hub. Going to call it a “lock plate”….
Theres another piece ill just call the “finger”

Opening the trunk
When you press the button(s) the motor turns counter clockwise rotating the concentric so the lock plate can take pressure off the lock latch (this action is seen when the trunk raises that 1/2” up off the body of the car). As the motor continues to rotate a small nub comes around and pushes against the tip of a spring loaded finger that pushes the lock plate out of the way allowing for the spring loaded lock latch to rotate away from the strike. Once the nub “rolls” over the tip of the finger the finger goes back where it started and the lock plate springs back against the outside arch of the lock latch. The motor gets it power cut when either the lock plates electrical bridge moves into its respective place or the motor travels far enough to disconnect from the underside (i think this is a failsafe so the motor dosent trash itself out)

Closing the trunk
When you delicately and softly close the trunk the lock latch rotates far enough so the lock plate that is pressed up against it springs back to where it was when the trunk was closed but not locked (thats the click you hear in wfooshee’s video just before you hear the motor engage and then the lock latch gets pulled into the cavity) which then because of the movement of the electrical bridge on the lock plate electrifies the motor . This “new” connection reverses the polarity thus reversing the motor that is now rotating clockwise. The nub rotates up over the tip of the finger and then the concentric action pushes the lock plate down, with quite a lot of force, into the lock latch catching the lock loop in the jamb of the trunk pulling the trunk down automatically. How convenient…

It looks like there is about a 65% travel rotation concentric with quadruple mechanical with 2 electric cycles that has two circuit boards with double and triple bridged contact points to kill, transfer, or reverse the polarity to the motor.

If you get to much junk in the trunk and have to put weight on the lid forcing it down till it catches and the concentric pushes down on the lock latch it places a lot of strain on the plastic assembly trying to pull/crush that much weight, think trash compactor pulling instead of pushing, either cracking out the body or striping one of the 3 cogs in the transmission (thats the white part between the motor and the black plastic assembly). If your unit has this crack and it separates too far you will never get the trunk open again because it separates a different finger gizmo thing away from a rotating disc with a notch in it that is attached to both the egress and the key cables. If this goes out neither the egress of key will open the trunk.

Theres also a lot of force when the nub rotates around contacting the finger pushing the lock plate up against a very heavy spring. The tip of the finger also wears when the nub passes over it. Thats the problem with this one. Either that or the big crack in it caused by someone jumping on the trunk to close it I would imagine.

I dont think there is any way to repair the worn nub, finger, pin, broken cogs in the transmission, bridge points, and a cracked out plastic housing. Even if you could repair any of these items its an absolute bugger to get the thing back together because of the big damn spring (the one under the three screws) used on the lock plate. I did initially get it back together after a few tries and a few choice words by holding the spring back with a piece of dental floss. The old type dental floss, not the Glide crap, but i was dealing with two separate pieces (broken) when there should be only one.

I think by the time you spend on the thing you would have ended up paying yourself $8 a hour to save $200 bucks. This isnt really a repair video just a whats inside video. It would be a pretty good system if the finger would be a little tougher metal AND MADE WITH A METAL HOUSING! Im curious if the new ones have been re-engineered. Maybe theres a aftermarket one that will do a better job but there was nothing wrong with the one on the ol’ 98 X308. I personally could do without these soft close trunks. Why do we need them anyway.

Take care,

Jon

 

Thank you for the video. I was correct in how I thought it came apart and still believe I would not have been able to put it back together in working condition. Now I can rest easy knowing my time and $ was well spent using a replacement.

 

We might be able to make on good latch with two failed ones but to

assemble we need a jig or a couple of jigs.

Any production engineers out there?

 

A lot of times there is a part in an assembly intentionally made weak as a sacrificial piece in case of serious malfunction. I encountered that in a 2003 S-Class Mercedes which ended up being stuck in park. The release for the shifter was operated electrically, and tripped by a plastic lever which had broken. That lever was not easy to replace, but the difficulty was all in getting the shifter out of the car, not so much in getting it disassembled. There was a guy online who made metal replacements, but I figured since mine lasted almost 20 years, I wouldn't go that route.

I haven't looked at the video yet, because I'm at work, but it would be interested to see what you think about the relative sturdiness of the pieces in the mechanical train, is the weakest link where it ought to be, protecting what could be a worse failure.

 

Indeed many times things are made to wear out, or break, a low cost or easy to replace part. In the case of the latch for my vehicle I did not try to take it apart because I figure after I grind off the end of the "pin" and pop it apart all the "bits" will pop out and get lost. I believe the one in the video could be repaired by building up the cam on the part that rotates and opens the latch. However with a broken outer case it would not have been worth repairing. I suppose it there was enough spare parts one could sell "rebuilt" one. I know I saved my old one in case the new one breaks. Then I will have one to use for parts.

 

If you decide to go with the mini sledge hammer to the “finger” route, and can get it back together, make sure to do dry runs with the trunk open. Make sure to test the egress and key. If that egress disc separates nothing shy of cutting a hole in the backseat and crawling thru and taking a sledge hammer and a big dang chisel will break it apart so it can release. Hate to see that happen.

I dont think the wear on the pin was the culprit. More so the “finger” is the problem…. And the big damn crack.

Ill get the one pulled out of my car probably over the weekend and see what up with it.
-----
Your welcome Rancheroguy

Couple more for ya

Jon

 

There is nothing indicating a sacrificing part. The motor will to continue to rotate until it reaches its cut out point.

I dont think the overpacking scenario would damage the transmission initially. The planetary would even the torque placed on it and the main force pressure is at the lock plate. But, over time gears get brittle and just normal operation they snap off.

I you one could repair the plastic by filling in both sides of the crack with ABS cement and reinforce the outer perimeter with safety wire or zip ties, one on each side. Be careful not to separate the egress finger from the notch inside when spreading the crack. Along with the hammer to the finger fix, if applicable. Fairly certain the transmission can not be repaired.

Jon

 

Jump ahead 3 minutes on the second video.

Sorry if the following is redundant…

I believe the finger is the main problem. Its to short at the tip. The multiple wear points through out multiple moving parts that open up simultaneously exceeding tolerance capability so the nub just rolls over top of the finger before it can bump into the lock plate. (see in slow motion vid).
I was initially thinking it was the finger tip was worn down because of the heavy spring but I didnt see metal dust wear evidence in the area. I can speculate that it was made to short.

I tried variations of bending the finger where it arches, kinda didnt work. The bend needs to stay to follow the arch radius when rotating. If the tip is pounded out too far it hits the hub of the concentric… If its pounded out to wide as it makes its radius it bottoms out the lock plate up against the inside body so the nub cant pass over the tip of the finger and it will stop dead most likely stripping out the transmission. On the nub’s return rotation it pushes the finger up against the other side of the body most likely stripping out the transmission. Ive disassembled and assembled this thing a dozen times making finite filings, poundings, and testings to get it just right. You can make it thinner on the sides in the tip area than what it came from the factory.

Draw out a pattern of the original finger on a piece of paper before pounding out.

Original overall length 1 5/8”.... Make no greater than 1 3/4”, preferably slightly under.
On mine I only had to make the length of the tip 3/32” longer because I first bent the radius essentially making it longer to begin with before working on the tip, you shouldent to that btw. You should be ok pounding out the 1/8” longer at the tip. This reflects in the black inked outline of the original condition instead of the pencil outline (mine) with the “mistake” radius bend. Ignore the red pen outline.

Original overall width 5/16”.... Make 3/16” should work but no greater that 1/4” cause it will hit the sides.

The finger on the left in the video is the one from the junkyard, tester piece beat up but works. The one on the right with red sharpie isnt quite long enough and is definitely to wide. I gave it one more whack and then “lightly” smashed down the sides followed by some twisting and filing making it look like the tip of the one on the left.

I though of using a TIG welder to build up the tip of the finger, but I cant, because I dont have one, and dont know how to use one if I borrowed one, but I dont have any friends that have one…. TIG could work better in leu of a mini sledge and a anvil from the 1940’s??.

Testing:
You will have to get the screws out to remove the motor, that bottom circuit board is a bugger to unplug and plug back in. It can be done but if you want to get a spare thats cracked that you dont care about to remove the motor and test the finger you pounded and filed. Seen em’ on ebay for $80-$150

You CAN NOT run your rotation cycle tests on your good one because if the motor is in it you cant rotate it without causing damage to the transmission. Thats how I trashed the junk yard transmission. The one you see in the first video posted on post #18 im using pliers to rotate but there is no motor “attached” cause the transmission is free wheelin’.
The finger used in that video was grabbing just a little so I took it out and filed a little more off and messed it up then re-pounded on it and really turned it onto a jagged mess bit it still worked. You could buy a assembly on ebay, get some life out of it in your car, upon failure you would have 2, one as a tester, one as a repairer.

I would be open to sending you the spare finger I have and you can send me yours as a swap. Or you can send me the whole thing, I could repair it, and send it back. PM me.

Or just forego the extra work and cost involved in the testing phase and forget having two and get the finger out of the one and pound/file to the above specifications and hope for the best.

I initially was using dental floss for the heavy spring when putting back together. Drilling a 1/16 hole strategically place without drilling thru the circuit board was a lot easier. Mind the angle of the drill bit.

I got mine working so I guess the self gratification is payment enough, 20 hours later, I do work pretty slow though. Plus it was bugging me not knowing how this thing works and determining the flaw.


Ill get the images loaded in the next post.

Any questions please dont hesitate to ask.

Jon