2012 g37 sedan

The button on the trunk to open it isn't working, but the fob and interior trunk buttons work.

I thought it could be the antenna behind the bumper so I replaced it but that didn't work. If I probe the power wire in the antenna wiring harness I get no power under any conditions (engine on, off, key fob near/far, trunk button pressed/not pressed).

Should the antenna power wire have constant power since it needs to constantly be scanning for the fob?

I couldn't find any breaks in the wiring in the trunk, but stopped where it goes into the the interior

I'm thinking at this point there's either a break in the wiring harness somewhere (although everything else works fine, so seems unusual it would just be the trunk button) or problematic bcm?

Prior to this happening I did have the cars ECU flashed at an Infiniti dealership with the newest software because of a TSB .... maybe during the ECU flash the bcm went wonky and lost that functionality?

Is there any nearby wire I could steal power from? My understand is it's 6v and everything around it (e.g., license plate lights) is 12v so will fry the antenna.

 

Here's your FSM for "Door & Lock" which also covers iKey functions:
https://www.nicoclub.com/service-man...2012%2FDLK.pdf
Scroll down below the viewing window and "click here to download a copy".

I'm pretty sure the "Cancel" switch in the glovebox also affects that Trunk Lid Open Request Switch on the back wing, but you know that. Your problem could just be that button on the trunk lid. I don't think that's a simple voltage-type of circuit, it looks like a kind of scanning signal generated by the BCM. But I think pressing that switch simply grounds out that "signal".

Have you checked all the wires running through the rubber boots from the body to the trunk lid? That's a known spot to look for broken or frayed wires. You should be able to pop the boot out of the metal to check the wires. There might be a boot on each side of the lid.

That antenna in the bumper is only activated momentarily when the Trunk Lid Opener Request Switch is pressed. It's not constantly searching for the fob. And again it's likely a generated type of signal and not a readable voltage on either side of the antenna when activated. It only works momentarily when you press the button - transmitting a "call" to the fob and the fob answers with its code.

Hope you can figure it out.

 

Thanks for the direct link - I was tearing my hair out trying to find where it was in it (i.e., trunk lid open request switch).

The switch in the glovebox works as expected, and the wiring harness boot/loom looked good where it folds into the trunk.

Upon studying the FSM I see the open request switch needs to show continuity when the button is pressed. I tested continuity and mine has none, so hopefully it's as simple as that (I had actually disregarded the switch because all of my prior searching led to either the bumper antenna failing or the bcm, never the open request switch itself being an issue).

 

That may not be a common failure but anything can break. If there is no continuity between the two wires leading to the switch when the button is pushed, then that's the answer. I don't know how difficult it would be to replace but here's one:
https://www.ebay.com/itm/37553901506...3ABFBM2tvhoc9k

 

The trunk request switch would have been my first guess before the antenna but, no harm no foul.

To replace the switch you will need to remove the chrome trim piece (wanna "spoiler") from the decklid. From the FSM:



If you need the additional documentation download sections EXT (Exterior Trim) and DLK (Door & Lock) from the FSM link above. Shouldn't take more than 30min. to a hour.

Good luck and let us know how you made out.

 

I guessed antenna because I also had no license plate lights and had previously re-bodied the quarter panels due to rust (so I thought the bodyshop had switched the 2 harness plugs around and fired the antenna with 12v) ... turns out both my plate lights were burnt out, lol

Switch is backordered so just gotta wait for it to ship, but i'm pretty sure that is the cause.

I didn't want to wait for the backorder so I bought the entire trunk assembly from a junk yard ($200). Tested button, had continuity, fantastic. Plugged it into my car, and nothing. Re-tested button for continuity, it didn't have it. Hit the switch a few times, got continuity back, then lost it after 2 or 3 presses. So basically my switch is dead and the one from the junk yard trunk assembly was on its way out, my luck ... lesson learned, do not buy used electrical parts :/

 

Check the wiring in the flex boot- where the wiring from the decklid passes through to the trunk. It's quite possible you have a pinched wire. There have been several instances where the wires break as a result of the repeated opening/ closing of the decklid.

Worth a shot...

 

Trunk wiring is fine there - it's the trunk lid button - like I said, it worked (had continuity) when I first tested it, then it stopped working, then it had off/on continuity when I started hitting it... I guess it's hit or miss when you harvest electrical parts off junkyard vehicles .... waiting on website to ship me a brand new button now.

 

Well, it seems you're on top of the problem. I just find it odd that two (2) switches would be bad at the same time. Your OEM one, sure, but the odds the replacement was bad, ¯\_(ツ)_/¯

I am not a fan of coincidences but I digress.

Please let us know how the new switch works out.

 

Yeah, that's extremely odd that you would experience two instances of that particular switch failing - your OEM and the junk yard replacement. It's not impossible. But if that were a typical part failure we'd be hearing about it all day long in here. When you test for continuity, where exactly are you checking? Should be at that very first connector which looks like it's only a few inches from the switch. If that works then closely inspect the connector that one plugs into to be sure none of the pins or receptacles are out of place. Beyond that it has to be a downstream issue.

Keep going, you're getting warmer.

 

Not my lucky day I guess.

I got my brand new trunk button. Tested it and has continuity. Tested my original one and the junkyard button and they do not have continuity. So I plugged the new guy in, anddddd nothing. Re-tested him and still has continuity.

So I guess not only did my original trunk button die, and I got a bad button from the junkyard trunk lid, but I've also either got a broken wire or something wrong with the BCM. Boooo (can't be the antenna behind the bumper since I replaced that already).

 

Check the glove box "cancel" switch one more time.

This is not making sense. Where are you checking for continuity? The next step would be to check the harness. Terminal-1 of connector B304 (at the trunk lid request button) should have continuity to pin-61 of the (huge) BCM connector M121. Terminal-2 of B304 should have continuity to ground. You could test that entire loop from the BCM connector by connecting one side of your continuity meter to pin-61, the other side of the meter to any ground, and then press the button. Check to be sure that's working before you start buying more parts.

 

I flipped the glove box switch a few times - when flipped the trunk stops responding to any inputs to open it (e.g., key), when flipped back to the normal position everything responds except the button on the deck lid.

I'm checking continuity of the switch itself disconnected from the wire harness - open loop when not pressed, '0' when the switch is depressed. The new switch shows continuity when pressed; the old switch remains in open loop when pressed, so that was at least part of the issue.

I havn't checked the harness itself yet since that's harder to do, but that's the next step

 

As I suggested days ago, the wiring in the flex boot is a known issue for these cars (any car in general for that matter). The wiring gets fatigued with the repeated flexing and IS KNOWN to break. Usually it the camera that is affected but any wire in that loom has potential to break. (Older Jetta's were notorious for the flex boot in the driver door to just snap wires).



In the trunk itself, not the lid, locate the main body harness junction (trace it from the flex boot). From there locate and isolate the two wires for the trunk request switch and check for continuity between that point and the switch connector. Keep checking while moving the declklid up/down. If all checks good, then, you'll have to trace the wire from that junction to the BCM though the odds of one single wire failing in that loom are astronomical. Possible, but not too probable.

The bad switches notwithstanding, it has to be a wiring issue somewhere. I doubt it is the BCM as all other functions work as intended.

 

Yep, that's my next move - double check the wires in the flex boot and then see if there's an issue between the trunk junction point and the switch. I agree that BCM seems unlikely given everything else is fine.