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2001 BMW 330Ci Convertible Trunklid Wiring

(2002 BMW 330Ci)
in Willow Hill, PA on June 28, 2010
Symptoms: My car's brain is signalling a continuous warning to my dash, indicating that my trunk is open. The convertible top will not operate if the trunk is open, so it's stuck in

the down position and the rains are coming!

IN THE BEGINNING...My "reverse" and license plate lights weren't working. The bulbs were ok. The 10amp fuse for the "reverse" lights was blown. Put a new fuse in. No change,

but the new fuse didn't blow.

I knew that the wiring harness that runs from the trunk to inside the trunkLID via a rubber "snorkel" was stressesd and prone to chafing and breaking wires, so I wanted to inspect


On pulling the snorkel free at each end I immediately saw several problem wires (out of the 14 or so power and ground wires that run through it). I don't doubt that several failed as

I was trying to gently do the inspection.

I can't locate a good wiring diagram. If I could, I might not understand it anyway. At this point I have spliced in additional wire to reconnect all of the power wires according to color

code. I'm left with 6 unlabelled ground (neutral? - wiring isn't my thing) wires, all solid brown in color. I was able to get my "reverse" circuit working but I can't seem to get he

remaining "browns" doped out correctly by normal process of elimination.

The car has a central locking system; a power release for the trunk that NORMALLY can be operated from a button inside the car and als by the keyfob; a monitoring system that

includes the trunk open/closed deal that won't allow the top to be operated if the trunk is thought to be open (I verified this in the owners manual); and in case it matters - the

trunklid center brake light is of the LED variety (original equipment).

Last thought: I have checked all the fuses every-so-often to see if any blew during my work. None have.

Can anyone help me figure out the proper approach to finding the right brown wire configuration? Maybe there is a sequence or combination involved?

Thanks very much for your time.
Displaying 1 answers & 1 comments
Popular Answer
on June 29, 2010
I strongly suggest you do not proceed, please visit your nearest BMW dealer. Save yourself time and a lot of grief.
Your issue is rather in depth and cannot simply be walked through step by step.
Please leave it to the professionals or you will damage the General module or the Light module.
on July 03, 2010
I just came across this answer. To be honest, I thought I had some trouble navigating the RepairPal site in general. I finally decided it wasn't intended to be used for the type of inquiry I had, so I moved on to Just Answers.

In brief, their response was "just take all the brown wires to a good ground location. I did "argue" ~3 times that I didn't think it was that simple; due to monitoring etc etc. As an example, I reiterated that my reverse lights worked fine when connected to one SPECIFIC "mating(?)" brown wire within the bundle of 6, but would not work with any other browns in the bundle.

Very long story shortened, I succumbed and made 3 gangs of 2 browns each; connected them all to one larger-gauge wire; then took that to the battery ground terminal.

Results: 1) The "trunk open" warning light on the dash went out and I was able to raise my conv top.

2) All lights work EXCEPT the 3rd brakelight and the tag lights. These are obviously still needed, especially for my overdue state inspection.

3) For good or bad, that's where I'm at. If you care to try making some suggestion based on the current state of things, I woudl appreciate it. If not, I understand.

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