Join Date: Mar 2012
Location: Berkeley, CA
My Ride: BMW 330cic
| Hi all, new to the forum. I made an account just to thank djsilver for your post. It turns out I had the exact same problem, and a week of research I found the broken wire, patched it together and now the top works perfectly!
For the benefit of others who may have this problem, I'll add my experience. It is best you read over the convertible top manual pdf, as I'll refer to some of the parts using the names in that manual.
I didn't actually take it to the shop to read the CVM codes since I didn't want to shell out the $$ . So I decided to just check the wires first.
A common failure for e46 convertible tops is the wires inside the top harness breaking from flex. The harness is a bundle of wires inside a nylon casing that runs the length of the top, along the left side of the car. This harness is connects various sensors and motors to the convertible control module, aka CVM, which is located behind the left rear armrest.
SYMPTOMS (for me, at least):
- When I push the button to drop roof, the top will unlatch and raise 1-2 inches, but then stop. The button will keep blinking red. Pushing again does not help.
- Sometimes, pushing the button to drop roof does nothing at all. The button will not even blink after I release it.
- I manually lowered the top into the storage compartment (follow the "emergency lowering" instructions in the manual), then pressed the "close roof" button. The storage lid would unlock, raise, and then the top would come out but then stick halfway.
On both the lowering/raising sequence, it seems that it would stop when the tensioning bow or its related sensors was needed, leading me to believe it was the tensioning bow at first.
** Your symptoms may differ depending on which wire(s) are broken. From my research, it seems the recurring theme here is that the raising/lowering sequence only partially completes, then just hangs there with a blinking red light.
HOW TO DIAGNOSE if you have a broken wire:
1. Study the convertible top manual pdf in one of the above posts. Know how to manually raise/lower the top. Know the raising/lowering procedure as this will help you figure out where in the process it's breaking.
2. Remove the 2 rear left-side panels to access the CVM. (Google it, theres a youtube video showing how to do this on a e46 convertible, it was meant for install new speakers but it shows how to remove the panels.)
3. Look for the white plug on the CVM. Slide off the black lever, then unplug it. You can also remove the white part of the plug, this will make probing the leads easier. There's a tab you can lift on the white part which will allow the black inner part to slide out.
4. Using a multimeter, check for continuity among the pins. This (and the pin pdf in above post) should help.
The plug we are looking at is X13039. Each pair/triplet should have continuity; if it doesn't, you have a broken wire or malfunctioning part.
Pairs to test: (each pair should show continuity)
18 & 9; 17 & 8; 16 & 7; 14 & 13; 4 & 5.
Triplets to test - (any TWO of these three pins should give continuity.):
10 & 11 & 12; 1 & 2 & 3.
BMW has labeled the plug with pin ranges, which you can see if you remove the white hood.
For me, all the pairs/triplets had continuity except between 13 & 14. 13 was green/white, 14 was brown/yellow. This was for the cowl unlocked hall sensor, S145 in the pdf manual.
HOW I FIXED IT:
After I found the open circuit, I figured I could either a) run a jumper wire to the sensor, or b) split the nylon harness and find the break. The problem with a) was that I'd have to take apart the front cowl trim to expose the hall sensor, and I really didn't want to do that.
1. For me, I was pretty damn lucky. After browsing the forums, it seems a recurring place a wire breaks is inside the nylon casing, at the frontmost bend in the top. I decided to take a gamble and cut open the nylon at the front-most bend on the top. (This takes a little wrangling, but you can do it with simple scissors.) LO AND BEHOLD, on my first try, there it was, the green/white wire (leading to pin 13) broken. The brown/yellow wire, coincidentally, was almost broken too, as the strands were exposed and ripping apart.
2. I live right above a RadioShack. I bought some 18 gauge stranded wire and some electrical tape. Then I cut a small 2 inch length, stripped the ends and twisted the each end to the broken wire to connect the two. Then I wrapped it all in electrical tape. Two notes from this: a) this is not the longest-lasting solution as twisting wires is not very durable connection. You might want to try soldering your wires together. b) The strands in 18 gauge are way too thick, and are more likely to break from fatigue during repeated opening/closing - you should use a higher gauge.
3. I started pushing the open/close buttons. It definitely started working more so than it was before. It was having trouble raising the top, seemed like the top storage lid didn't want to unlock. I manually raised and lowered it a few times, and then FINALLY, the top would lower and raise entirely on its own.
4. I tested a few more raising/lowerings, and all works well! Boy was I happy!
- Wiring harness part at realoem: http://realoem.com/bmw/showparts.do?...=61&fg=10&hl=3
- Pictures attached show some of the work during the fix. I live in an apartment above some retail shops. So yes, you can do all this inside a retail parking lot. Just don't mind the occasional stare and people thinking you're leaving and wanting your spot.
Once again, thanks for your post djsilver. Hope this thread helps others in the same situation!