2015 Jaguar XF 3.0 S/C

Trunk non responsive. Does not open using release button (interior, under chrome strip or the remote key). Trunk does open using key blade. When I press one of the three buttons, the "trunk open" icon shows up on the gauge cluster and I basically need to open it witht he physical key blade to reset it as the trunk does not actually open.

Took the car to the dealership, they said the junk boxs is non responsive.
Part number: c2z32179
Cost: $1200 CAD + $800 labour + tax

I want to know if there is a way to fix the junk box, I'm guessing its the fuse box that is located under the fender liner. Could it be just a fuse? Anyone else had this issue? Dealership does not know how it happened.

 

Everything on the car and the boot lid is functioning. Shouldnt that entail that there is a bad fuse? Otherwise, wouldnt eveyrhtintg connected to the junction box fail or be unresponsive as well?

 

Well if you don't believe the dealer I would get SDD and see what codes the car has.
The modern day junction boxes have far more to them than just the old fuse and relay stuff.

There are dozens of failure codes depending on what has gone bad. It's just too complicated to figure it out on your own.
But you certainly could check that all the fuses are currently good. Do you know how to check the fuses quickly and easily?
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slow down and dont panic

there is a known fault in the boot ( trunk ) lid wiring where the wires break in the rubber covered loom where it goes from the body to the bootlid , take off the rubber cover and look at the wires , you may well ideentlify the broken wire right away

BB

 

Hey, I changed all the wiring loom with OEM ones (purchased from dealer). I changed the trunk latch and the motor it comes with. Everything in the trunk lid (Rear camera, license plate lights are working- everything in the car is working).

I'm freaking out since that is a huge repair bill for a faulty trunk release mechanism. The car has been sold, and was due to be delivered to it's new owner.

 

hey Club, unfortunately I'm not quite certain. I understand what a fuse is and I'm going to assume if be looking for some urn mark, or a broken connected in the U shaped fuse. Ifuse requested the dealership to check for the fuse but they did say that the junction box is unresponsive and as per their criteria, it requires changing the unit

 

ah , thats a pain

the other issue is water onto the rear right junction box coming through the bodywork vent in the metal bodywork ( hidden behind bumper ( fender ) cover)

this does destroy the rear junction box sadly , and replacement is the only option along with replacing or sealing the rear volumetric vent ( it allow air pressure to vent when closing the doors )

hope you get it sorted cheaply , used units can be used , but need CCF to let the car talk to the new replacement unit

BB

 

I have a scan tool, but it does not want to communicate with the car at all. Even independent mechanic I usually go to was unable to communicate via OBD since there is an extra ethernet connector that is uncommon (He could be wrong though)

 

That was my second guess, but the car has been stored inside a temperature/humidity controlled garage. I looked for signs of moisture or water too but did not find anything. Found a brand new unit for $350 USD. Trying to avoid getting it replaced throughout the dealer, at the same I do not want to risk fiddling with the electronics (especially a fuse box). Might have to bite the bullet on this one.

Goodness gracious

 

Found two listings. One has the exact part number matching to one I got from the dealership - $500 USD
Second listing does not have a part number but looks identical - $150 USD

Listing 1) $500




Listing 2 $150 - Belongs to a 2014 Jaguar XF - Does not specify model or trim (Importnat?)




Is there any difference? The various codes/number on the white label are different.

 

I believe the RJB has the cars CCF coded in and would need it written onto the new RJB using SDD

 

If you do want to check the fuse's in the car quickly. Use your DVM and using the resistance scale check between the two silver dots on the top of the fuse.
You can go right down the row in no time without taking anything apart.

Here is your fuse box picture;


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It's interesting that the "trunk open" indicator illuminates, I'd expect they have a microswitch to check if the lock mechanism is in the open position, so that might imply there is some movement on the lock mechanism ( even if it doesn't move far enough to actually open. ) Does that also illuminate if you open if with the key?

Can you hear any noises at all from the car when you click the remote button to open the boot? ( Thinking you may hear even a faint click from a relay in the rear junction box, though switching may be purely electronic ) You could try both with the trunk open, and closed.

Perhaps you have a poor connection where the loom for the lock motor is connected to the body.

If you can find the output for the motor at the rear junction box, you could try checking the voltage between there, and the battery negative with a multimeter, while getting someone else to press the boot release button.

For Info, the rear junction box contains a computer which communicates with other modules in the car via canbus, if it's canbus connection didn't work however you'd expect a lot more stuff not to work. I've heard the front junctions box has one or more relay like https://uk.farnell.com/panasonic/cp1...20a/dp/2103582 hidden inside, if you can trace the wire back to the junction box, you may be able to open the junction box, and see if that connection goes back to a similar relay which could probably be replaced by someone skilled at soldering. Similarly if the output is driven by a transistor I suppose. ( Though if the output pin of the micro-controller has failed, there may be nothing that can be done. )

The identical looking junctions boxes with different part numbers may well be programmed with different firmware (software in rom/flashmemory), it may be possible to move the software to a new junction box with a tool like xprog, but I think the dealer tools require you to have the correct firmware already programmed.

Phil

 

 

I ordered both parts given one is a bad, I wont have to wait another 3 weeks for the next one to arrive.

As for the trunk, there is no audible sound, vibration/movement when using the 3 release methods. Using the key blade springs the trunk open (almost violently). The trunk open indicator comes on if one of the 3 buttons are pressed, and illuminates when the trunk is opened with the key blade.

Please note that all the wiring looms in the boot lid were replaced along with the trunk latch and motor.

Dealer reported that there is no moisture or water leak in the trunk. The junction box simply 'shorted'. It wont make things worse, but the only repair is to change the junction box. I'm debating if buying part at dealer is the safer bet since there is not guarantee on supplied parts and I will be subject to labour x the number of parts tried.

I'll check the fuses to, thanks for posting the image.

 

Looking at your first video it looks like it is difficult to lock too, though sounds like the soft close motor is trying.
In your second video are you releasing the lock with the key? ( It seems the soft close backs off, so wondered it it's unlocking via the button(s) when you're locking the mechanism with a screwdriver like that )

Is it a new lock mechanism or used spare? ( thought I could see wear on the moving part, but maybe it's just grease - there are several variants of the latch depending on vin number! Perhaps the bodywork is subtly different, or the smart junction box programming is different to match )

The following post may be worth a look it seems the adjustment of the strike plate is critical, so it might need a bit of tweaking since you've replaced the latch )
https://www.jaginfo.org/threads/soft...0/post-2353097

 

I had a similar problem with my XK8. There is a wire bundle that runs from the interior fender in the trunk up thru a rubber grommet and into the trunk lid. Inside that wire bundle are five very thin wires. I un-clipped the wire bundle at both ends and removed it. (pretty simple). I then took a razor blade and opened up the bundle and found that two of the five wires were broken. One was for the trunk latch button and the other was for my license plate light. I soldered the two wires back together, taped the bundle back together and re-installed. Everything works fine. I priced the lead link trunk lid bundle. Jaguar wanted $186.00. That was a while ago so it might be higher. It was pretty easy to repair if you have access to a soldering tool. Hope this helps.

 

On some cars the latch is powered from the central junction box ( accessed by a plastic door in the outer side vertical panel of the front foot-well ) rather than the rear junction box, so it's worth checking Fuse 16 in that junction box. The windscreen washer pumps can also leak in such a way that it pushes water through the wire(s) back to that junction box.
There's a thread over at jaginfo.org about that (link)

Logically it sounds to me like a bad connection to gnd ( battery negative), there are switches in the latch indicating if it's ajar, and they pull the input to gnd ( the inputs on the junction box will provide a voltage ( pullup resistor), and check for current flow to detect if the switches are open or closed. ), so if the gnd connection is poor ( high resistance ) when the junction box gives a voltage to the latch actuator to open it, the gnd pin on the latch will be pulled up to a higher voltage, and to the input on the junction box that is checking for the ajar switch this is equivalent to the switch opening, which would explain why the dash indicator illuminates when you try to open it. A bad gnd connection could also explain why the soft close mechanism has difficulty closing it. Gnd pin on the latch is pin 5, and on the soft close motor is pin 4, I'd suggest checking the resistance between each of those and battery negative with a multimeter. ( And/Or perhaps better still checking the voltage on those with the motor and lock connected while actuating the unlock button )

P.S. Make sure you've not left the smartkey in to trunk when you're having difficulty closing it ( it automatically unlocks if they're present when you close it so you can't accidentally lock them in! )