Retractable top problem

[Vetracr]

Well it was bound to happen. Beautiful sunny day in Florida. I back car out of garage and push button to lower the top. Trunk opens, top retracts but trunk won't close. Red light over button on. Great. Now what do I do? Can't drive with trunk open. repeated pressing of open button does nothing. I shut engine off and restarted. This time I press close top button. Thankfully top comes up and trunk lid closes. I rarely put top down so this caught me by surprise. Has anyone had this experience? If so how did you solve problem? I'm guessing its one of the microswitches but the shop manual I have doesn't explain which switch does what and location pictures are almost useless. Any suggestions before I have to go to stealership?

[Asbjorn]

Mine has had the same problem three or four times - usually it happens if I have not used the car for a long time. The problem always disappears by itself after a few hours. Sometimes it helps to get out and close the roof using the key in lock method.

The problem may disappear if you use the roof more often. The switches, hydraulics etc need a bit of use to stay in good shape. And be careful when you wash the car.

In any case, don't just drive with the top down on sunny days. That's such as waste man.

[ZeusFour]

I had the same problem. Figured out that the reason was weak battery. Quick help for the problem is to run your car with little bit higher revs (charges little bit better) or charge your car battery with proper battery charger.
Would be good to charge battery once on a while to avoid this problem . I do this if car stands longer time.

[fmorelli]

There are lots of microswitches that really one needs BMW software to talk to the TCM - Top Control Module. Here's a crazy one. I was having intermittent roof issues. Turns out my outside temperature sensor was having issues - the top uses the temp coming from the COMBI as the TCM won't operate the top at less than 12 celcius I believe. When I changed the sensor, problem went away. I noticed the temp in the speedometer cluster was sometimes way off.

Filippo

[Kessler35is]

Originally Posted by fmorelli

There are lots of microswitches that really one needs BMW software to talk to the TCM - Top Control Module. Here's a crazy one. I was having intermittent roof issues. Turns out my outside temperature sensor was having issues - the top uses the temp coming from the COMBI as the TCM won't operate the top at less than 12 celcius I believe. When I changed the sensor, problem went away. I noticed the temp in the speedometer cluster was sometimes way off.

Filippo

This must be a safeguard for the hydraulic system, low temps could thicken the fluid and cause damage.

[alexm9999]

I had a similar problem that only showed up when the car was sitting in the garage for several hours or in cool temps outside overnight. Every time I brought it in for service the dealer left it sitting in the Texas sun for several hours and couldn't reproduce it. I finally convinced them to try it first thing in the morning, which DID reproduce the problem. After that they kept my car inside and were able to reproduce the problem at will. They finally replaced the hydraulic cylinders on both sides plus a few switches.

[fmorelli]

Scary. So they replaced a bunch of discrete components until it worked.

Filippo

[tranquility]

I maybe had a glitch (red light) that happened <4 times and I've had the car for 8 years thus far. The 2 cardinal rules are:
1. use the roof often when weather permits, if you don't use it, you 'lose' it in terms of something going wrong w/ it
2. NEVER use battery to operate it, so only when the car's on so as to not prematurely kill the battery

[alexm9999]

Originally Posted by fmorelli

Scary. So they replaced a bunch of discrete components until it worked.

Yes, and no. Until they were able to reproduce the problem all they could do is work off diagnostic codes from the last failure. My biggest complaint with BMW service is they don't look beyond their diagnostic flowchart to figure out root cause of a problem. Luckily my service advisor was willing to work with me and together we were able to resolve the issue.

[paris1]

Originally Posted by alexm9999

Yes, and no. Until they were able to reproduce the problem all they could do is work off diagnostic codes from the last failure. My biggest complaint with BMW service is they don't look beyond their diagnostic flowchart to figure out root cause of a problem. Luckily my service advisor was willing to work with me and together we were able to resolve the issue.

It always pays to establish a close working relationship with at least one key person in a dealer service organization. Mine was with a particular service advisor as well as one of the service techs (before he left for greener pastures). It’s been a year now since I left the factory warranty fold, but I still feel I can always contact this one individual for help/advice if I get in a jamb.

[fmorelli]

Originally Posted by alexm9999

Yes, and no. Until they were able to reproduce the problem all they could do is work off diagnostic codes from the last failure. My biggest complaint with BMW service is they don't look beyond their diagnostic flowchart to figure out root cause of a problem. Luckily my service advisor was willing to work with me and together we were able to resolve the issue.

Interesting. I know a fair bit about the top, having had some issued I had to diagnose. One has to read the BMW technical engineering docs on the Z4 which discusses its design and operation in detail. Using BMW's diag software, they should be able to talk to the TCM and at least sort out if there are faulty microswitches, or a missing temperature signal, et cetera. Leaky hydraulics can only really be done by visual inspection.

But part of my point in providing the document URL above ... one has to wonder how many BMW techs are knowledgeable and experienced in working through top issues? One would think with all the E9x convertibles, it would be common knowledge ... but ...

Filippo

[bigendbob]

Have a look here:
https://z4-forum.com/forum/viewtopic.php?f=46&t=95385
And elsewhere on this forum.