1st Gen R52 Cooper Convertible Help! Convertible Top Non Functional.....

Well, I scanned my car with the Schwaben scan tool and besides finding a few error codes that I didn't expect, there were no error codes for the top. The tool said all was OK. So, I'm going to be looking for broken/compromised wiring affecting power to the sunroof motor. Seems like a good starting point given that the sunroof needs to work before the top will go down.

 

The saga continues.....

'Did some work today. Another, more detailed scan showed no faults, though during a component by component activation check, I found a blank result for the right stowage latch. I pressed the "continue" button on the scanner and that cleared it and it then showed "contact open" as it should.

I did some voltage measurements at the connector that plugs onto the sunroof motor. The blue wire with the white stripe showed 12+ (14+ with engine running) volts when I checked it by pressing the close button. (Nothing with the open button as it should.) When I checked the red wire with the black stripe, I got nothing when pressing either the close or open button. (Open button should have produced voltage.) Both these tests were done with the meter grounded to the motor frame.

So, it appears that I'm not getting voltage to the motor when I press the open button. And I'm not getting a complete circuit and voltage to the motor when I press the close button either. The two relays that operate the folding sunroof motor not only send current to the motor, but they also provide the path to ground through the as well. The default position of the relay is making a connection to ground. When one button is pushed, the corressponding relay sends current to the motor and the path to ground from the motor goes through the other relay. When the other button is pushed, this path is simply reversed. I'll be checking the relay itself tomorrow or during the week and also checking the wire path from the relay to the motor on the red/black wire.

Also, I tried cranking the sunroof open manually and when I opened it far enough, I was then able to press the down button and the top completely came down per normal. This was nice because it made it very easy for me to get into the back and remove the left rear interior side panel so I can get at the wiring and relays. And the top went back up again per normal though I had to manually crank the sunroof closed. What's interesting is that the hydraulic pump would not shut off like it normally would. I chalked this up to the non operational sunroof motor which normally would close the latches and then shut off the pump. No bigger at this point.

I also pulled the sunroof motor and checked it. It runs perfectly in both directions and while I was at it, I lubed the gears before I reinstalled it.

So, here are my theories on why there's no current to the sunroof motor.

The first and I think the most likely is that the relay that controls the opening of the sunroof is malfunctioning. It's not sending current to the motor to open it and since the ground path for closing the sunroof also goes through this relay, that's why the motor won't run even though I confirmed 12+ volts at the connector when pressing the close button.

The second theory is that that the red/black wire is broken somewhere. This wire provides the juice for the motor opening the sunroof and also provides the ground circuit for closing the sunroof. This theory also makes sense.

I will check the wiring first as it is easy to check. And I'll check the relay as well, even if the wire checks out bad. Of interest is that when I press the open and close buttons, the appropriate relays click, but though they are identical relays, one sounds different from the other. That may tip the scales towards the relay being the problem. But we'll see.

FYI, the Schwaben scan tool is really great and easy to use. If anyone's looking for a top notch scan tool, I highly recommend it. I can do so much more than the much simpler ones that work with phones and tablets and can only read the usual OBD2 codes. The Schwaben unit also reads and clears and analyzes all the other body, suspension, ABS, and airbag codes. Very nice. And though it's 200 dollars, it's already almost paid for itself as my local shop wanted 125 for a full vehicle scan.

 

The Schwaben is my first ever scan tool and I'm glad I bought it.

If it turns out that my problem is something more mysterious than a bad relay or broken wire, I may just call it quits there and have a convertible top specialist take care of it for me. At least I should be able to save some money because I've already torn the left rear interior panel off.

I will update everyone when I know more. Hopefully this evening.

 

My pleasure!

 

Well crap......

Seems there's a break in the wire somewhere between the relay socket and the folding sunroof motor. And that harness is not easy to get at or replace/repair. And it could be in more than one location. Crap again....

The first thing I did to confirm the break was to swap the two relays involved with opening and closing the sunroof. I still got current on the blue/white motor lead (to ground) and no current from the red/black wire. (Same as before.) I then removed both relays from their sockets and confirmed which terminal in the socket supplied current to the sunroof motor. The two relays are identical so the terminal location in one socket would be the same in the other socket. I checked the socket supplying current to the blue/white motor wire and presto, I had continuity (as expected). I then checked the corresponding terminal in the other socket and.....nada. Open circuit.

'Looks like I'll just pull the other interior side panel out and then call around for someone who has experience with the 1st gen mini convertible top and see how much they'll charge for the necessary work. The wiring harnesses are relatively cheap, so I may have both replaced if they have to go in all the way. I was sure hoping it would be a simple fix. I suppose I can take some solace in the fact that I narrowed it down so much which hopefully should save me some money.

About an hour later.......

I've isolated the break in the wiring by hooking up my Fluke meter to both ends of the broken wire (at motor and at relay) and reaching in and manipulating the wire as it bends around various parts of the top frame. The break is in the main curve where the rear most part of the top mechanism pivots. If I can just get in there, I could splice new lengths of wire in there and repair the break. Of course, the wires could be seriously compromised at some of the other bending points, but at least this would get me going for awhile. So, does anyone know how to access the back of the mechanism through the outside without removing the entire top from the car or needing to take the top halfway apart? Is there a trick to pulling back the fabric at the rear of the rear window? Or am I stuck doing a major disassembly?

Or, is it possible to access the wiring at some point just south of the bow, cut it, and then feed/pull in new wires? Or just run a new wire and leave the old in place? The problems as I see it is that the wiring harness is held in place in numerous places with clips and tie wraps and that would hinder my removal of the old wiring. And even if I got new wires in there, I'd not be able to properly secure them in place and while that might work for awhile, the chances of pinching/cutting the new wires would be increased.

Meanwhile, the sunroof is working again, though I haven't tried opening the top all the way as the wire that I manipulated could easily just go open circuit again. So for now I'm still driving with the top up. 'Supposed to rain tomorrow anyway.

Thanks much for all your advice!

 

One other thing I may tackle are the broken plastic "bushings" that are on the sliding roof mechanism and which slide in the grooves/tracks of the convertible top frame. The bushings got old, cracked and fell off and on the left side, at least, there are none which makes for a more rattly top and it doesn't close as effectively as it should. Does anyone know if it's easy enough to pop the slides out so I can measure the tabs the bushings would go on? I can easily enough design new ones on CAD and then machine them at work as we've to a nice Bridgeport. Heck, I could even fabricate them by hand. Delrin would be my material of choice, I think.

What I'm talking about is in #3 of the attached jpg.

 

Well, the saga of the non-operational top is at an end. As I determined, it was a broken wire in the harness that goes up to the sunroof motor. I chalk it up to having used the top so much. By my estimate, I’ve put it down and back up easily more than 2,000 times in the past 6.5 years. Probably more.
I took the car to BR Racing in Los Gatos and they determined it was something they’d prefer someone else worked on, so they took the car to their interior/convertible top pro. A shop that works on a lot of custom cars and high end stockers. (There was a beautiful 59 Vette there that had more than 400,000 dollars put into it already.) Anyway, these guys did the work and got me up and running again. To replace the wiring harness, the top had to be removed from the mechanism. Harness was 235. Labor 500. Since they were doing all that work, I had them also replace the slider mechanisms for the sunroof. The one on the left had broken and lost both of the plastic bushings that run in the tracks. Mini want’s 580 dollars for those so OUCH. And labor to install and adjust was 1080. Ouch again. Total for all top work was 2395. Double ouch. Of course, the local Mini dealer wouldn’t even consider just replacing the sliders as they said their people (and other independent shops) could never seem to get the job done right. They wanted to replace the entire top bow assembly with the motor sliders, mechanisms, etc. to the tune of nearly 2000 dollars just for the parts. Never mind labor or replacing the wiring harness.
As a side benefit, the top now works as new or better than new. And the whistling noise that I had when the top was up is now gone because the left side of the sunroof now closes properly against the top of the windshield frame. The top material is still in good shape and they also installed the two rear rubber/chrome trim pieces on either side of the third brake light. This is my third set and hopefully my last.
Thanks to all for your suggestions and comments.
Oh, I have the original slider mechanisms and the right side still has the plastic bushings intact. I’m keeping them so that should the plastic bushings ever crack and fail in the new sliders, I can simply measure and recreate on CAD the two bushings and then machine new ones so if there’s a next time, I can simply replace the bushings and not the entire mechanism. Crappy decision on Mini’s part to not make these an item that can be purchased separately.