DavidF

So, trunk lid wont latch closed ('04, 545i). Replaced the latch and all was well (sort of) for one month and then same problem happened again. The new latch (when working) would noticably humm when the trunk lid wasin the open position, but it worked. Then it would not latch closed just like the original problem. I assumed the "new" latch failed in the same manner as before. Picked up a new latch under BMW's part warranty, installed, and nothing. Problem continues. All wires look intact all the way to main harness (can see wires in trunk lid hinge tube). I have tried disconnecting and reconnecting battery, lock unlock all doors with remote, hold door lock (with key) in locked/unlocked position for 10 seconds or more (same with trunk key lock), etc. I inspected release button micro switch (at trunk lid) and it is not stuck closed. I have not removed/inspected inside cabin release button yet.

I can disconnect latch wire harness and reset the latch so it operates manually. As soon as I reconnect power to the latch, I can hear the latch "resetting" (so motor inside latch is working), then the latch won't latch until I remove power.

Anyone run across this problem before and found the solution? I am hoping my general module is not at fault

DavidF

Wow, can believe no one had had this problem before (or has advice on how to fix). Anyway, I read all faults codes and there are no stored fault codes within the general body module. Interior trunk release button operates correctly according to INPA. I have verified the latch is working properly by exchanging with latch from my E46 (same part). So, I suppose I have to start looking for a broken or shorted wire...probably within the trunk hinge.

DavidF

For others that might stumble on this post when searching...it's fixed. Turned out to be a broken ground wire where trunk wiring harness enters trunk hinge tube.

turboawd

i thought i read on here somewhere, where someone else had the same issue...a broken wire by the hinge.

DavidF

I would not be surprised that others had the same problem. I should have know to check the wiring out first thing. Broken trunk harness wires are a common fault with the E46 (I have a E46, but have not had the problem yet). Anyway, the wires break from fatigue due to the constant back and fort motion each time you open and close the trunk. Over half of the wires in the bundle had cracked insulation. I attempted to move the wire bending/flexing point when reassembling.

daMANiack

Hi,

I found out that as soon as the electrical cable is attached, the cable attached to the key lock rotates anti-clockwise and puts the trunk lock in the OPEN position.

This means that the trunk lid won't latch as the hook can't rotate downwards and hook into the U-shaped fitting. As soon as I dis-connect the electric cable, the cable to the key lock releases and rotates clockwise.

I've dis-connected the trunk release button in the cabin and the boot release soft rubber electric cable to micro switch thinking these might be in a CLOSED (pressed) position but the trunk lock mechanism is still faulty.

Any special steps you can give me to I don't dis-assemble the whole car?

Did you have to remove the cables from the KEY LOCK, centre TRUNK RELEASE mechanism and the centre soft rubber micro switch?

Cheerz

Sublime

Thanks for posting the resolution to this problem - even though I love working with wires I probably would have just ordered a new latch assuming that was the problem. Now I know not to be so impulsive. Hopefully this doesn't happen though...

daMANiack

Hi,

Thanks for your knowledge and suggestions, I removed the boot lining over battery and released fixing so I could pry open the other lining to show the E60 boot tube that the wires are fed through.

The solid brown wire going to the lock was broken and 2 other wires had the insulation split showing copper wires.

I cut the 3 wires, slid over some heatshrink tube insulation, soldered the wires back together, heat shrinked the insulation tubes, wrapped wires with electrical insulation tape, then taped all the wires together again using electrical insulation tape, then wrapped wiring lume with cloth re-inforced gaffer tape.

As someone suggested, I changed the position where the wires bend when boot opened/closed.

Tested, all is working perfectly.

Cheerz

daMANiack

Hi,

I decided to take some pics to show broken wire and cracked insulation to anyone that may have this problem. I suspect the BROWN wire broke first as it's a thicker wire and feels more rigid, the thinner wires are more flexible.



Cheerz

Original

I have a 08, 528i and trunk was not opening so I was using the valet key and then trunk will not close so I started to search the forums and thanks to this thread I was able to find and fix my car problem. Here are few images of the wire that was broken.
Hope this helps someone before taking it to dealer.