RoadHazard

Ever since I had the convertible top gear sets replaced on my 2005 Boxster S (987.1), it's been showing a "Failure Convertible Top Ctrl." message every time I close and latch the top. The error message is 100% repeatable.
The other symptom is that starting the car with the top already closed and latched causes the electric motor to run briefly (about 1 second), as if it's tightening the top and clamshell. This isn't normal. Normally, the motor runs for a second after you raise the top and close the manual latch. It shouldn't repeat that process when starting the car with the top already closed and latched. However, if I start the car with the latch un-latched, it doesn't do the tightening maneuver.

The up-and-down motion of the top and metal clamshell all seems fine. They go up and down as they should, so it doesn't look like a gross mechanical problem.

Here's what I've done so far, but with no change in symptoms:

• Replaced the ECU under the left seat,
• Removed and disassembled the left-side transmission looking for mechanical problems,
• Tested the two electrical limit switches inside the transmission,
• Verified that the switch inside the windshield header works,
• Sprayed connectors with electronic contact cleaner,
• Thrown a dead chicken over my left shoulder, sacrificed a goat under full moon, etc.

Any other ideas?

RoadHazard

Here's that shows the problem.

I recorded the left-side transmission as I closed the top from roughly halfway closed to fully closed. When it auto-stops, I latched the windshield header (okay, I actually stuck my finger in the header switch). At that point, the top moves a bit more, which is normal. What isn't normal is that the car then displays, "Failure convertible top ctrl." and the up/down switch stops responding. I have to remove the key from the ignition and put it back in to clear the error. Unfortunately, putting the key in and turning it causes the electric motor to turn a bit more, which definitely isn't normal.

I need to find the cause of the failure message, and I need to stop the electric motor from mindlessly over-tightening the top and the clamshell every time I start the car. I assume both symptoms have the same cause, but you never know...

GRIEHL

im having the EXACT same issue and its driving me INSANE, did you fix this?

RoadHazard

Nope. I still don't know what the cause is. It's driving me nuts, too.
I haven't worked on it for a while, hoping my head will clear and I'll have an "aha" moment. So far, no luck.

My current hunches are:
- a damaged connector or pin on the 3-wire harness between the left-side transmission and the ECU under the seat
- a bad wire somewhere between the left-side transmission and the ECU
- incorrect software configuration of the ECU
- a bad switch inside the transmission
- metal dust from a stripped gear contaminating one of the switches inside the transmission
- transmission cam disc is on backwards, or turned, or out of alignment
- switch is riding on the wrong part of the cam disc (high vs. low side)
- incorrect transmission starting position somehow confuses the ECU
- bad 12V relay that turns the electric motor on/off is somehow operating on its own

Feel free to try all of these and let me know if it works for you. ;-)

GRIEHL

who did your rear module?

kjb1122

Hi both,recently purchased a 987 2005 Boxster S here in the UK ( Guards red ). Car was purchased with the roof failed and water ingress. Passenger side pretty dry especially in area where the module sits, drivers side quite wet. Any how, I removed the roof in its entirety over the weekend to basically start again. Both push rods missing, tonneau cover passenger side snapped. Rain collectors ripped, holes in and not fitted correctly. The plastic transmission cover which sits under the track rail passenger side was also fitted poorly. So took roof pff, bought a new arm for tonneau cover andseller supplied me with two new design 911 push rod arms.

I then purchased new rain collectors for each side, fitted everything correctly as it should have been, and today now have re installed the roof fully.

Only issue now, everything works, except......I get a convertible top failure alarm just after latching the roof closed, can hear motor driving the tonneau cover fully home, but the fault comes in. Rocker switch will then not operate. Switch car off and on again and the roof automatically tries tightening again?? can hear the motor whirring.

Open the hood is fine, roof will seat down and no alarms, close the roof, I get the fault.

Please tell me someone has experience of this, and we can resolve together? it must be something fairly straight forward. A limit clearly is trying to be achieved I think.

RoadHazard

Oh, boy. Do I feel your pain. Sounds like you have exactly the same symptoms as me. And so far, I haven't cured it.

Like yours, my top goes up and down just fine, but I get the error message and the unusual/unwanted extra motor activity. The problem is not mechanical. I can disconnect all of the convertible top hardware and the problem persists with or without everything disassembled. Sticking my finger in the windshield header switch behaves exactly the same as closing the mechanical latch. I'm stumped.

Wild guesses:

• Perhaps there are two electronic modules involved -- the big one under the left seat and another one elsewhere?
• Maybe Porsche needs to bless the replacement module with a special code, VIN, password, or configuration detail?
• Maybe the simple limit switch inside the left-side transmission gear train is faulty?

Really hoping you/we find a solution for this.

RoadHazard

I got it replaced by ECU Doctors in Florida. I sent my soggy one in; they sent a dry one back. They even sent me a second unit (a replacement replacement, if you will) after I hinted that maybe the first one might be the cause of my weird problem. Evidently not: the second one behaves exactly like the first one. So either BOTH replacements are bad or my problem lies elsewhere.

kjb1122

Same here, we will get to the bottom of it I'm sure. My roof when I start the car does the weird added extra movement, unless I unlatch prior. Which I think I will continue to do going forward. To prevent further damage.

Highly annoying, I bought this as a summer toy to live in the garage, it will never see a winter / rain again with me.

Would be nice to get it resolved, as I love it.

Stay in touch going forward, my email is jblowers1@hotmail.co.uk

kjb1122

So reading your previous comments over again. I see you have also effectively disassembled everything and are only getting this fault after reassembly. Why are you fixated on the left hand side transmission? out of interest? has your right hand side had the arms off at the same time as the left? or was it only the left side that you took apart? do you think we could have re-assembled the transmissions slightly out of sequence and therefore the limit switches are not being made, which is why the roof is trying to drive itself further closed to make the limits? what if we disconnected the push rod arms and tried to step the transmissions on a bit via the switch then re-connect and test, trial and error just keep doing this possibly??

RoadHazard

Well, yes and no. When my car got rain-damaged a whole lot of things misbehaved. Horned honked, lights flashed, windows went up and down, etc. It was undriveable until I had the ECU under the seat replaced and both transmissions rebuilt. After that, everything worked again -- but this weird "failure convertible top ctrl." message popped up. Overall, the car was much improved, but not 100% fixed. I've been chasing it ever since.

A fair question. The left-side transmission is slightly different from the right-hand one in that it has a pair of small electrical limit switches in it that tell the car's electronics when the top is fully up or fully down. The right-hand unit doesn't have them because, well, why would the car need two sets? As far as I can tell, these switches are the only thing that tell the rest of the electronics to stop moving the top up or down. They're how the car "knows" the top has moved enough and it's time to stop. The third switch -- the one in the center of the windshield header -- simply tells the car you've done the safe thing and latched the mechanical catch.

On my car, both transmissions were rebuilt with new gears after the old gears chewed themselves up following a rainstorm that flooded the electronics under the left seat. It lost its mind and tried to force the top to open even though the car was parked, off, locked, and latched shut. Instant stripped gears. :-(

As you suggest, I have removed all the mechanical arms from both transmissions, leaving just the gear trains themselves and the black metal "boomerang" thingie. Then I watch them turn as I press the top up/down switch in the cabin and both transmissions turn through about 180 degrees of motion as they raise (or lower) the imaginary convertible top. I did this just to be sure there wasn't some other hidden switch or sensor attached to the top itself that might be faulty. Nope. The problem persists whether the top and its lever arms are connected or not.

You're right that it's definitely possible to have the two transmissions out of sync, so that the left side goes up slightly faster/slower than the right side, but that's a different issue to prevent mechanical twisting and (as far as I can tell) it doesn't apply here. Even so, I've spent hours tweaking them to make sure the top goes up perfectly aligned.

I thought maybe the limit switches inside the left-hand transmission might be faulty, but I tested them with a voltmeter and they're fine. So maybe the switches are okay but the mechanical cam they ride on is misaligned? Could be; I don't know how to test that. Or maybe that cam is turned around by 180 degrees? Maybe, but to my eye that doesn't seem possible. Or maybe the rain damaged additional electronics elsewhere. The fact that you and I and a few other people all seem to have the same problem tells me it's not a random fluke like a broken wire or bent pin. No, there's something more sinister at works here... ;-)

M. Essaie

I remember reading somewhere that through the run of 987s there is a change in behavior of the top when it is being put up. On mine, which is a 2006, no matter how long you hold the switch to move the top up, the motor eventually stops with the clam shell still up a few inches and the windows dropped. The driver has to latch the top closed to provoke the clam shell drop to the final position and the rising of the windows. On others, these last two actions happen as a result of holding the switch long enough. That would seem to indicate that some control units will be differently arranged.

RoadHazard

Interesting. I didn't know about that.

Like yours, the convertible top on my 2005 Boxster S stops by itself no matter how long I hold down the switch. I have to latch the latch (or stick my finger in the header switch to simulate latching it) to force that last little bit of motion.

That plays into my prejudice to blame the software. I know that my replacement ECU had to be programmed for various specifics of my car: manual vs. automatic transmission, incandescent vs. LED lights, etc. I wonder if the top closure method is also a programming option and that it was programmed incorrectly for my car. That would be very tough to test without yet another replacement ECU. Or, unless someone knows how to program the unit at home.

loutadd

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If you replaced the plastic gear in the top transmission you need to line up the notch on the transmission housing with the cam notch first then connect the rods to the v shaped lever.

RoadHazard

What notch in the transmission housing? Here's a photo of my left-side transmission as it came out of the car. I put the top in the fully down/back/open position before removing the transmission and detaching the metal lid. Nothing else has moved.