Key fob won't open trunk?

[Kenny167]

So I've recently just purchased a 2004 M3, and the key doesn't open the trunk. I'm assuming it's just the key itself, because I can unlock and lock the car with it, and both the button on the trunk and the trunk release inside work, so the actuator is fine. I don't have another key, but I think that's just what I need to fix this. Any ideas?

[MarcoZandrini]

Does the key rotate in the trunk lock? If it doesn’t turn the lock was changed by the previous owner. If it does rotate then the lock assemble is disconnected from the latch assembly. Go to www.realoem.com and enter the last 7 characters of the car’s VIN. Hit enter and bookmark the page. Scroll down to trim. Also, get a second key or you’ll get stranded miles from nowhere (h/t Cat Stevens).

[Kenny167]

Does the key rotate in the trunk lock? If it doesn’t turn the lock was changed by the previous owner. If it does rotate then the lock assemble is disconnected from the latch assembly. Go to www.realoem.com and enter the last 7 characters of the car’s VIN. Hit enter and bookmark the page. Scroll down to trim. Also, get a second key or you’ll get stranded miles from nowhere (h/t Cat Stevens).

Sorry, I forgot to say that the key physically works in the lock but won't remotely open it. Remotely, I can lock and unlock the doors, so I'm assuming it's the key's internals that are messed up.

[MarcoZandrini]

Ahhhh! It’s likely that a few wires in the elephant trunk (it runs from the body to the trunk/boot lid) are broken. Thus is a fairly common issue in the E46. Basically, you need to replace the broken section of the wires by soldering new, multi stranded wires. Use shrink tubing for each wire.

[Kenny167]

Ahhhh! It’s likely that a few wires in the elephant trunk (it runs from the body to the trunk/boot lid) are broken. Thus is a fairly common issue in the E46. Basically, you need to replace the broken section of the wires by soldering new, multi stranded wires. Use shrink tubing for each wire.

But wouldn't that mean that the button in the footwell wouldn't work? Because it works just fine...

[MarcoZandrini]

Good point! Do, let me rehash this. The key can mechanically lock/unlock the trunk lock. The track lock can be unlocked via the button on the interior foot panel. The remote locking system locks/unlocks all doors but does not lock/unlock the trunk lock. Is this correct?

[Kenny167]

Good point! Do, let me rehash this. The key can mechanically lock/unlock the trunk lock. The track lock can be unlocked via the button on the interior foot panel. The remote locking system locks/unlocks all doors but does not lock/unlock the trunk lock. Is this correct?

Yup. I took the key apart and as soon as I did, a resistor fell off the board. So that's almost definitely my issue, I found a key in the junkyard yesterday and so I took the circuit board from that and I'm going to use it as a circuitry salvage board. I'll solder a new and good resistor on and hopefully I should be all set. I did some testing with a multimeter and found out that all of the switches on the board itself work electronically, so if I replace this resistor it should hopefully fix this mess!

[Kenny167]

From all this, it seems to me like the issue lies within the car itself, because I have another E46, a 325, and I put an oscilloscope to the key's pcb and on both keys saw similar activity going on throughout the key whenever a button was pressed... So maybe a wire in between the receiving of the signal and the actuation of the trunk is grounded? I'll find some wiring diagrams and try my best.

[dhurley34]

May need to have the trunk unlock by FOB function reenabled in INPA.

[Kenny167]

May need to have the trunk unlock by FOB function reenabled in INPA.

Ok, I have everything set up for that, where can I find that option? I did a lot of playing around with INPA and never saw that... Never looked in the body electrical control though

[dhurley34]

I havent messed in INPA in a few years but it should be with the door unlock/lock by remote and window roll down/up via remote section.

[Kenny167]

Could it be this option?Screenshot_9.png

[Kenny167]

I don't think that's the right option, because that seems to be for the switch above the license plate. When the car is locked, it obviously doesn't open, but when both doors are unlocked it will. I think this HKL_SPERREN_BEI_ZS option is disabling this, but I'm not sure.

[dhurley34]

before you go messing in INPA, try to resync the key to the car.

[Kenny167]

Yup... already done it. That was step number 1, then validating that the key is functioning correctly, and now it's onto the car itself... I get the feeling there's a wire being grounded out, but I can't seem to figure out if there is a wire that is specific to the trunk opening functionality, as the wiring diagrams are fairly confusing and convoluted.

[Kenny167]

So, an update on this. I finally got NCS expert working, and was messing around with it. I was able to set up my headlights the way I wanted, but only 1 or 2 of the changes I made to the GM5 module appeared to do anything. Also, the panic mode is enabled, and holding the trunk button doesn't trigger it, telling me that the ZFS receiver might not be communicating well with the GM5, or something like that. I might check the K-bus shorting block and see if anything is shorting it out, as that would definitely cause this. My lights are supposed to flash when I lock and unlock the door car, but they don't, and to me that means my GM5 has an issue.

[Kenny167]

Finally, a clue! So I was idly going through the FSW_PSW.TRC file, and found that "HECCKLAPPE" was set to "nicht_aktive". Seeing as heckklappe translates to trunk, I figure this is my issue, but what do I have to do to get this to work? It's a part of the SHD module, and I'm not sure if in NCS expert codes the SHD module along with the GM5 module, or what? I made the correction to my .TRC file, but don't know how to finalize this programming...