Rear trunk release button not working

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Feb 10, 2020 | 07:00 PM
  #1  
I needed to change the trunk lid on my 96 xj6. The wiring was not a big deal but the trunk release button is not working. The replacement trunk had a bad actuator which I replaced with the one from the original lid. Now the trunk lock works when I push the dash panel switch and my fob. The trunk lights work as well as the plate lights. The original switch from the lid was damaged.

I have some questions. What does that small micro switch do that is on the locking mechanism? The push button switch on the lid, is this just a momentary on-off switch? How is this momentary switch wired. What else can the problem be.
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Feb 10, 2020 | 07:23 PM
  #2  
G’day Jomo,

The small micro switch on the latch, through the BPM (body processor module), controls the trunk/boot lights and enables/disables the remote locking/unlocking.

The problem with the boot/trunk release button is more than likely a broken wire in the loom near the RHS boot/trunk hinge, it’s a common problem.

Cheers,
Jeff.
Reply 1
Feb 10, 2020 | 07:35 PM
  #3  
I was thinking that the problem would not be in the loom as the button worked just before the trunk go rear ended. But I am rethinking that and maybe the wires for the switch got damaged in the accident.
Also do you know how that switch works? Where the wires from the switch go to etc?
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Feb 10, 2020 | 09:48 PM
  #4  
G’day Jomo,

The button is just a momentary contact push button switch.

All the wiring for anything in the trunk lid goes past the RHS hinge, I’d be checking there for a broken wire or maybe you could unplug the button switch and short the contacts and see what happens. It may be that the push button switch is faulty. Spray it full of contact cleaner and work it a few times and try it again.

Cheers,
Jeff.
Reply 1
Feb 10, 2020 | 10:25 PM
  #5  
Jeff,
Tomorrow I will go by the switch and short out the two wires. If that does not do the trick, then I will go by the hinge and short out the two wires. If the trunk unlocks (I'll close it by hand with the lid open), then I will find the break in the wire. Knowing that it is just a momentary switch is very helpful.
Thanks,
Jomo
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Feb 11, 2020 | 04:23 AM
  #6  
In my case, the problem was the micro switch itself. Pretty commonly available online, and replaced it for pennies. slight pain to get it out though...
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Feb 13, 2020 | 08:45 PM
  #7  
I tested the switch today. When I disconnect the plug from the trunk lid switch and shorted out the terminal the lock, which I locked by hand, opened up fine. I did this a few times. For some reason I locked the lock again by hand and when I put the plug back in the lock unlock. That was surprising. I then locked the lock and the button did not work. I disconnected the plug and when I reconnected it the locked open. I then concluded that the switch is not good. The button itself is moving in and out very nicely so I am sure that there is a short inside that switch somewhere. I will remove it tomorrow and see if I can get it going. Fortunately I have a continuity meter.
Anyone have any advice on how to fix the switch?

Thanks,
Jomo
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Feb 14, 2020 | 01:22 AM
  #8  
Sorry to keep going on about the hinge wiring, but the problem might still be there.
When you were testing it sounds like you had the boot open and it worked. The wire might not be completely broken, and might make contact when the lid is in a certain position, but not when lid is shut.
It might be the switch, but for every one switch fault there are 100 hinge wire faults!

Good luck,
Reply 1
Feb 14, 2020 | 09:16 AM
  #9  
Thanks for going on about the hinge. I don't mind that at all. Please confirm my reasoning that it is not the wiring at the hinge.
If the button switch is not being pushed in then when I connect the plug then the lock should not open. The thing is that the lock is opening every time I connect the plug to the switch. I am assuming that when the plug is not connected then there is no continuity between the two wires in that plug. But when I connect the plug there is continuity because the lock opens and this means that the switch is in the closed position all the time. Does this sound 100% valid to you?

Alternatively I can check the continuity at the switch when I get some time. In fact because of your insistence that it might not be the switch I will do that!

Jomo
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Feb 14, 2020 | 04:45 PM
  #10  
You have a good point, and I’m not sure. Maybe pushing the switch is push to break so plugging the cable on actually makes the connection? Don’t know! The best way to check the switch is with a continuity meter, so let us know how you get on!
Reply 1
Feb 14, 2020 | 05:55 PM
  #11  
I will check to see if the switch is working backwards from what I am thinking.
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Feb 14, 2020 | 08:59 PM
  #12  
G'day Gents,

On the circuit diagrams that I have the boot/trunk switch is normally open and so momentary contact to activate.
I'd try drenching the switch with spray contact cleaner and working it a few times then blowing it out, it may take a few attempts.

Cheers,
Jeff.
Reply 1
Feb 15, 2020 | 01:15 AM
  #13  
Or if at fault a good second hand one is not to expensive https://www.ebay.com/itm/Jaguar-XJ6-...-/124066218514
Reply 1
Feb 15, 2020 | 11:01 AM
  #14  
It is the switch. They use a generic micro switch which costs about £3 new. Used to be able to pick them up at Maplins before they closed.
Reply 1
Feb 15, 2020 | 07:20 PM
  #15  
Yes I agree with @countyjag that it's almost certainly the switch.

Replacement is straightforward.

1. Remove the boot plinth from the car, then remove the 2 screws that hold the switch unit to the plinth. Mine were very, very rusty and had to be drilled out.






2. Drill out the rivets that hold the micro switch in the unit, and cut the cables attached to the old switch






3. Solder the old cables to the new micro switch, and insulate as best you can. I used heatshrink. The switch needs to be NO (Normally Open), and be a momentary switch (not locking). My new switch was multi function (both NO and NC depending on terminals) so make sure if yours is that you use the correct terminals - test with a meter before soldering.






4. Attach the new micro switch to the original switch unit with small screws and nuts. Use thread locker to ensure they won't come loose. Install the repaired switch unit back on the plinth. Job done.








Reply 4
Feb 15, 2020 | 11:19 PM
  #16  
This is great to hear. I was going to replace the entire switch but replacing the micro switch will be the way I go. However I will 1st try to save the switch! Thanks for the pictures.

Of course I will let everyone know how this turns out!

Jomo
Reply 1
Feb 17, 2020 | 02:38 PM
  #17  
I replaced the microswitch and all is working fine now.
Thank you all for your help!
Jomo
Reply 0
Feb 18, 2020 | 01:19 AM
  #18  
Well done!
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Sep 29, 2021 | 10:40 AM
  #19  
Trunk Won’t ‘Remember’
I ordered from eBay one from Poland. To be aware, my card was processed in Luxenberg but eBay has buyer protection so not too worried.

Has anyone run across your trunk that was adjusted to a less than full opening and no matter how many times you reset it it always goes back to the lower setting? I’m wondering if that could’ve been done at a dealership and an override the default fully opening because maybe someone had the opposite problem opening all the way and they were hitting the trunk lid or something.
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