E85-85 Convertible - Electrical Problem

[James-Z4-2006]

I have a 2006 3.0Si Z4. Soft top worked 100% fine until a few days ago, when putting the top back up, it closed ~95-98% then just stopped and the red light at the up/down buttons started flashing. No noises, no hesitation, just stopped cold/dead. Turned car off/on, still nothing and red light flashing.

Pulled the red ring in the trunk, put it down the rest of the way and used the allen-key method to activate the windshield locking hooks and close it 100%. Red light still flashing; up/down buttons don't do anything - windows don't move, windshield hooks release motor doesn't engage, zilch.

Since it's a RED light blinking and not ORANGE, I didn't think it was the micro switch in the trunk for the shelf being down, but just to confirm I took my micro switch out yesterday and tested it w/ an Ohm meter and it does change values upon clicking and unclicking the lever; so I assume that works fine. And I haven't changed the truck shelf or had anything in the trunk for a long time.

Researching online, I found several discussions on this one, mostly due to the hydraulic pump failure due to water damage. I live in a dry zone, hardly ever rains, and the car is always inside, so hardly any water exposure, so I don't think I (luckily) have any issues w/ the hydraulic motor. And this seems to be a purely electrical problem.

I also took off the small access panel behind the driver seat and found the Convertible Top Control Module (white box). Unscrewed the mounting nut and pulled it out to check cable connections. Appears to be connected solidly, but I don't know if there's a way to check any specific voltages or continuity on specific pins to diagnose whether this module is working properly or not. Does anyone happen to know if there is a way to diagnose this module?

I could try buying a used module and swap it out, but don't want to waste the time/money doing that if it isn't the cause, or risk causing other issues putting a different, potentially faulty module in the car if the current one if fine.

I do have a basic BMW scanner and have this code: "22 Switch Cowl Panel Unlocked; short circuit to ground." I believe the "cowl panel" is at the bottom of the windshield (is that right?), so I'm not sure if this means there is something faulty with a sensor in the top bar of the convertible top that attaches/locks to the windshield..? Or if this could mean a cowl panel for the rear of the convertible top...?

Anyone experienced this electrical problem before and have any guidance?

 

[Motionblurrr]

I have good news. Unfortunately, I myself had to live with a broken top for a few years due to your exact problem. It has been the bane of my existence with this car since the motor wasn’t that old and I ended up getting the constant blinking red light, windows wouldn’t roll down, latch at the front wouldn’t unlatch. I googled too deeply and found nothing that matched my symptoms (except transport mode but that’s not the case).

Your issue IS electrical and it’s within the loom that runs inside the soft top, from the top latch all the way to the motor. Thankfully, you can repair it yourself by soldering the broken wires together and heat shrink wrapping where it was broken. I did 2 layers of shrink wrap on each soldered joint.

You have to slightly open the top, unscrew the torx bolts that are facing the front of the top, and lower the “flap” that would be the inside lining of the soft top (the fabric that sits over your head while you drive). The loom might LOOK like it’s in perfect condition because it’s a braided sheath but the wires are broken, kinked or snapped on the inside. You have to cut it open with a razor blade and check it out. Later I wrapped it up in electrical tape when I was done.

I included a photo to show what I mean when I say it’s the loom that’s your issue!

After the soldering and shrink wrapping, the windows roll down and the top unlatches like before when you hold down the 'top down' button! No more blinking red light.

Unfortunately for me, I got a double whammy: broken loom for so long that eventually the motor seized from sitting in water even though I never used it So both the loom and motor failed me since I waited too long!

Good luck!

 

[Zedebee]

Great photo. This is becoming quite a common problem on roadsters now. Hard to find without stripping the loom, but easy to fix.

 

[Motionblurrr]

Great photo. This is becoming quite a common problem on roadsters now. Hard to find without stripping the loom, but easy to fix.

Yeah, it seems that this is another stage of small problems of these aging cars. Thankfully it’s not too bad of a fix. The frustrating part is there not being enough issues worldwide where it’s easily diagnosable by googling. The soft top motor is easily more common so it’s hard to wade through all that info for this specific problem lol

 

[James-Z4-2006]

Thanks Motionblurrr. Really appreciate the response and details on how to fix this electrical problem. Will work on it later this week and let you know the results. Fingers crossed I can easily find the broken wire!

 

[Motionblurrr]

Thanks Motionblurrr. Really appreciate the response and details on how to fix this electrical problem. Will work on it later this week and let you know the results. Fingers crossed I can easily find the broken wire!

No problem! Let me know how it goes! Oh yeah, in that photo, I slid the cable under that joint in the top so I can work on it from the outside of the car. It's not supposed be hanging out that way lol.

 

[zed_fan]

Getting the exact same problem on my top. The computer seems to get confused on where the soft top is. Sometimes it gets stuck cycling the latch when opening. When it's open and I want to close it, it just flashes red and refuses to do anything OR pressing the button doesn't even trigger any lights. I have to wait until the next day for the computer to properly reset and then it will allow me to operate the roof. Irritating.

I did pull the codes and it complained about an open circuit in the cowl panel. Gotta be a broken wire. Wonder if it's worth buying a whole new harness if the current one is becoming frail and brittle? It's $250 so a bit steep...

 

[Zedebee]

I did pull the codes and it complained about an open circuit in the cowl panel. Gotta be a broken wire. Wonder if it's worth buying a whole new harness if the current one is becoming frail and brittle? It's $250 so a bit steep...

That would be throwing money at an easy fix. I do not imagine that fitting a new harness would be particularly easy either.

 

[James-Z4-2006]

Here's what I did and learned yesterday:
- Manually opened the half-way, and took the inside top/front plastic cover off to inspect the wiring harness everywhere I could access it, including along the inside leading edge to the motor that locks the roof to the cowel panel
- Everything looked fine in terms of any "crimp points", and wiggling the wire with the key in the ignition and trying the up/down buttons didn't change anything
- The wiring harness is unfortunately "buried" inside the section of the lever arms and canvas top attached to it, and I couldn't find an easy way to remove the top, and didn't want to damage it, so I didn't force it off. May be attached somehow from the inside of the frame...? (Anyone know for sure?)
- I found the section of the wiring harness that comes out of the top frame / lever arms, behind the driver's door, and examining the wiring and location, thought this might be an area with a potential crimping / pinching action and thus cause the problem. (SEE PICTURE)
- I tried to pull the harness up vertically, but it appears to be split into 2 sections, one running up the lever arm and one running under, thus I couldn't pull it out vertically.
- Was able to feed a yellow string under the harness, as I wanted to activate some "movement" in the electrical lines to see if I could get a connection... WHAM! there you go. Pulling the harness w/ the string while pushing the up/down buttons, everything worked just fine.... until it didn't...
- The top went up about 50-60% of the way, then stop again, and no amount of pulling or wiggling the harness line would allow it to complete the closing cycle. Tried this a few times and the same result each time -everything works in the lower 50-60%, but above that, seems to have electrical connection failure. Thus I'm assuming there is a pinch point somewhere in that area of the wiring that once the top/lever arms get to that position/angle, the wire connection is completely broken and thus stops working.
- So I'm pretty sure I know where the problem is, now the challenge is accessing it and finding the broken wire(s), as I think there are ~14 wires inside one of the harness lines and ~6 in the other, according to the pin connector diagrams I found online.
- Agree the earlier post that replacing the full wiring harness is tough job, given that one #%$^ section that is buried in the frame/top that I can't easily remove/access. Unless someone has a solution there...??.... So I'm planning to search for the fault in this lower section of the wire harness and try to fix it there instead. Would be ok w/ buying a new harness (sucks to spend $250), but I think getting it in might be a bear.
- I think the challenge is going to be fully accessing this bottom section of the wiring harness to get enough of it exposed to easily cut open the loom and work on the wires to find the fault. But hopefully not. I'm hoping it doesn't require any removal of the full top frame to access the harness, but we'll see. I ran out of time yesterday and unfortunately probably won't be able to get back to this until next weekend, but at least now I know where to start. Will circle back w/ more info as I do/learn more.

Any guidance from the Z4 gang on tackling this one? Anyone taken the rear interior panel off and accessed this section of the wiring before?

 

[Motionblurrr]

Did you cut open that black braided sheath on the loom and take a look at the wires inside that black braided sheath?

 

[James-Z4-2006]

I didn't yet. My plan is to cut it open in the bottom section first, to see if I find a faulty wire there. And if not, then plan to cut into the section that runs along the interior top, above the driver's window - the section where you found your break.

BTW, when you cut open the sheath, it looks like each electrical line is covered in a different colored plastic/rubber coating (standard wire covering). Was the line break you found clean through the rubber outer layer as well as the inside copper line, or did you see a kink spot in the rubber outer layer and then upon cutting that open you found the line broken inside? Trying to understand how you were able to locate the exact wire that was faulty and where exactly it was faulty (if it didn't break the line completely). Thanks.

 

[Motionblurrr]

I didn't yet.

I made the same mistake a few weeks ago. :rofl: I thought it was ok since it looked brand new but no, it is absolutely kinked and broken underneath that sheath. Mine looked spotless and brand new and I even touched it and ran my finger across it to make sure. I was wrong however, (and members here told me so).

The reason I said to cut open the sheath on the section I took a photo of, is because that's where the wire is exposed most to repeated folding, closing and flexing due to the soft top. Not to mention changes in temperature will cause the wires to harden, soften, bend, kink and fracture. Some might be on their way out too.

No, you just cut open the black sheath covering and take a look at the wires that are separate inside and see if any are kinked, about to snap, or fully snapped. That's all. No need to cut through the individual wire outer layer unless you're planning to solder it.

 

[zed_fan]

I noticed the wires for the top latch motor hall sensors were a little rough so i patched them up but still not working properly. Ripped open the rest of the harness that you have access to and all the wires looked fine. VERY strange. I did remove the top a year ago to replace the hinges and wonder if I messed up the routing of the cables at this point.

I loaded up ISTA to monitor the convertible top status. Open/close buttons work. Hall sensors for the top latch motor and hall sensors for the soft top also work flawlessly. When the roof does get stuck, I can see on ISTA it sends a signal to the top latch motor to unlock but the motor does nothing.

I think at this point I will replace the convertible module with a used one and see if anything changes. If still doesn't work I suspect it has to be the harness is damaged in a spot I can't see without removing the top. What doesn't make sense is that it works the next day so you'd think damaged wires shouldn't ever work which is why I'm leaning towards the module... Time to start throwing parts at this roof :rofl:

 

[colb]

Really sounds like zed_fan has a broken wire(s) in the roof loom, resonable to assume it starts working then stops and then works next day after the cars electrics have gone to sleep. Change in tempreture overnight is probably the cause of making and breaking of contact on a broken wire(s) in the loom when its requested to move the roof. My hunch would be strip the loom and search for breaks before considering putting a replacement module in, I expect a replacement module may well have to be coded to the car like other modules fitted to the car. Since he checked the relays/switches and saw the demand for the front winscreen motor being sent and the motor not doing anything its probably best to test the motor with a 12v feed to see if it works, if it runs then look for broken wires.

 

[enuff_zed]

I expect a replacement module may well have to be coded to the car like other modules fitted to the car.

I doubt this is the issue, but I had a problem where the roof would only operate with the ignition.
It would not work with the engine running. Very odd.
However, on the advice of Alan (No.5) I swapped the control module and it cured it. Fairly easy to access through the little panel behind the passenger seat.
My point is though, that it was a straight swap, with no coding required.

 

[colb]

Thats interesting to know, would have thought it may need coding to the car like some of the other modules so they could talk to each other. When using BMW Scanner 1.4 diagnostics it reads the convertable top module for faults so maybe it is a stand alone module and dosn't need to see any other modules in the cars system. Alan No5 is definatly the man to know the workings.

 

[zed_fan]

So I opened the top and it refused to close again even after waiting the next day. The problem is that releasing the red hoop will still not allow you to raise the top manually because when it is electronically opened, the top becomes latched to the center console. Thought I got stuck with a permanent open top but I just found out something new and feel like a dummy. So you know the button in your center console to open the compartment? There is another button above it that seems like it does nothing...but actually it is the manual override to the center lock! Hold it to keep the lock open and then you will be able to manually raise the roof.... :roll:

Anyways I've ordered a used roof module to see if that will help. Hopefully it's plug-and-play but I do have NCSExpert if some coding is required.

 

[BumpyZ4]

The module is plug and play, no coding needed.

 

[zed_fan]

Reporting back after finally getting into trying to fix the problem. Roof module was not the issue.

Ordered new roof wiring harness. Removed the roof and replaced it. The old wiring harness had a few knicks in the insulation but nothing that would clearly be a short. Reinstalled everything and that was not the problem after all. By the way if you order a brand new harness you must check the pins on the connector that goes to the cowl panel hall sensors. The new one black/red was pinned to 1 but must be pinned to 4 so that was fun figuring out that problem...The roof got confused and would just blink red :headbang:

Anyways same problem persisted -- roof unlatches and latches again. I removed the roof latching motor to inspect the wiring and it looked fine. 1 of the connector pins was a little loose where it joins with the wire so I used a multimeter and sure enough there was some resistance and not full continuity. I fiddled with it until i got continuity and finally the roof works again!

This problem will probably come back once the wire works itself loose again from vibrations. I couldn't figure out how to depin the connector to properly fix it. Oh well at least the problem is figured out for now :driving:

 

[Bmwdon1941]

So, I’m tagging on to this post in hopes of getting some help.
I pulled my top to replace the motor, ended up a second time to have hydraulic cylinders rebuilt.
After second install, now the top will not fully latch. The claw motor does work, but won’t fully clamp it shut.
After researching, I’m pretty sure I do not have the hall sensor, that SHOULD be affixed to the hinge arm (drivers side)NOT
Fastened in place, it’s just hanging loose.
Could this be my problem.
Top lowers and locks down, raises fine but won’t latch
(I may have gotten in over my head on this)