RoadHazard

The error message comes on after I close the overhead latch, never before. In fact, I can raise the top all the way until it stops and then wait any amount of time (1 second, 10 minutes, 4 hours, etc...) with no error message. But as soon as I close the latch, the motor turns for 1-2 seconds and the error message appears. Taking the key out and putting it back in makes the motor turn again for 1-2 seconds, which is obviously wrong behavior. The top should not move when starting the car.

Some Boxster owners have told me to replace the switch inside the windshield header but this doesn't make any sense to me. If the switch didn't work, then latching the latch (which pushes on the switch) would not trigger the error. Also, I can monitor the real-time status of the switch with my Foxwell OBD-II scanner and it's quite reliable.

RoadHazard

I can't do this. As soon as the error message appears, the switch no longer works. I have to cycle power (take the key out and put it back in) before the top will move up or down.

loutadd

I would be surprised that it’s the latch switch. When latch is closed and windows are up open latch and see if windows drop a little 1/4 inch approximately. If so the latch switch should be okay.


When you push on switch to close it stops automatically, then you close latch. Message comes on and switch stops. Put key in and moves again.

My thought is that when you put key back in and v lever moves again the distance between latch closed position and of the key in v lever position is the amount of distance that needs to be adjusted.

Try this

1. Open top completely with switch until it stops automatically in open position.

2. close top with switch until it stops automatically.

3. Latch top and wait until v lever stops.

4. Remove key.

5. Make sure latch is in closed position and insert key.

6. Wait until Vlever has stopped with latch still in closed position.

7. Remove key with latch in closed position.

8. Insert key open latch and open top with switch until it automatically stops.

9. close top with switch until it automatically stops.

10. Latch top.

Hope that works as I have run out of ideas except if you can find someone who has 987 and you can see where v lever
position is when fully opened or closed

RoadHazard

Thanks as always for your help. I know it's hard to troubleshoot something you can't see or touch. I appreciate getting fresh ideas. Here's what happened:

Dashboard displays "Opening convertible top" for the time it takes the transmission to turn about 180 degrees and stops automatically in the fully open/down position. That was easy!

Dashboard displays "Closing convertible top" as the transmission rotates the other direction about 180 degrees and stops automatically.
Pause for about 10 seconds...
Dashboard displays "Convertible top not in limit position." Is this normal? Or is this just a standard safety reminder to latch the top before driving away? It seems like the top should be in limit position if it stopped by itself.

Motor moves for 1-2 seconds. Dashboard displays "Closing convertible top" again while it moves.
Pause 2-3 seconds....
Dashboard displays "Failure convertible top ctrl."

Done.

Motor moves 1-2 seconds.
Dashboard displays "Failure convertible top ctrl." This extra motion is obviously wrong. Top should not move up/closed when starting car.

Done.

Done.

Here I deviated from your instructions. I unlatched the top latch *before* inserting the key because I know from past experience that the motor will move again as in Step 5.
"Convertible top not in limit position."
I press the switch to open the top and hold it until it stops automatically in the fully open position.
"Opening convertible top."

I press and hold the switch to close.
"Closing convertible top."

"Closing convertible top." displays briefly.
Pause 2-3 seconds...
"Failure convertible top ctrl."

RoadHazard

New Harebrained Ideas:

1. Maybe the two switches inside the transmission are moving around slightly. Perhaps the limit switch gets activated when it touches the high part of the cam disc, but then the switch moves and it's no longer pressing against the cam? Jiggle?
2. Or maybe the big cam disc itself is moving slightly. Maybe there's slop in the gears. As the top closes the cam disc pushes on the limit switch and motion stops. But then the cam disc rotates backwards slightly so the switch is no longer activated?
3. Maybe the system relies on the mechanical weight or inertia of the convertible top? I've been testing with all the hardware removed, but maybe it's not supposed to work without it?

It's unfortunate that my Foxwell NT530 scanner only displays the status of one of the two switches inside the transmission. I don't know why. Seems like it would be easy (and useful) to display them both, but it doesn't.

As far as I can tell, there are exactly three dumb on/off switches controlling this entire process, and they're all connected to the same electronics module under the left seat. Everything else is software. So... either one of the switches is bad, the electronics module is bad, or the software is bad. I've tested two of the three switches and they're both okay. (I can't observe the third one.) The module has been replaced -- twice -- with a refurbished unit from ECU Doctors. Both replacements worked exactly the same way, so either they're both bad or ECU Doctors didn't program them correctly. Both options seem unlikely. What else is there?

loutadd

Top not in limit position means that the cam v lever position is not correct.

I assume that you have not connected the v lever to the pushrods.

when you latch the top with key and the top is in the closed position I believe you said switch will not work therefore you can’t move the v lever any further. Then when you insert key in the v lever moves to what I believe is the limit position which should be the position when your top is latched.

Since the switch will not allow you to move the v lever any further I suggest that you move the v lever with a drill through the top motor cables to the what I said above is the limit position.

With regards to the micro switches there are two one for top up one for top down which get activated when the pointing arm hits the high side of the cam plate. I tested both with a multimeter when I had to replace a gear (the original is a plastic gear).

Good luck

RoadHazard

That's correct: the two transmissions and V-levers aren't connected to anything right now. They're turning air. ;-)

If the transmission stops on its own, it must be because the cam has moved the switch. But 10 seconds later it says, "top not in limit position," which sounds like the cam has NOT moved the switch. How can both be true? Is the cam moving backwards? Is the switch moving? Is the software faulty? I'm out of ideas.

I will try your experiment and see if that changes anything. Maybe I'll get lucky!

loutadd

Let me know how it goes.

My thought process is that when it stops automatically the micro switch is riding the high side of the cam plate (micro switch in)

When latch is closed the micro switch is still riding the high side of the cam plate and has not hit low side of the cam plate (micro switch out). When you put key in motor the micro switch is still riding high side and moves until it hits low side.

When it hits low side switch works for top down.

If you only use switch to close top you will never be able to get to the cam position where the motor moves when you put key in. Use drill to move v lever to this position which should have the micro switch out since it is on low side of cam plate.

loutadd

Did it work

loutadd

Hey Roadie,

were you able to fix problem with the proposed procedure?

If that didn’t work let me know, I have one other thought to propose.

RoadHazard

I did a few more examinations to be sure what was going on inside the transmission.

First, I held the cabin switch to move the top all the way down/open. There are no error messages. (This has always worked fine.) The transmission rotates clockwise until it stops automatically. I then took the transmission out of the car and removed the metal lid to look inside. The electric switch has just barely started to touch the high side of the cam. This seems normal and correct, and it's why the top stops in that position. No surprises. I reinstalled the transmission.

Next, I held the cabin switch to move the top all the way up/closed -- but I did not close the latch. The transmission rotates counter-clockwise until it stops automatically. There are no error messages during this process, unless you count the "top not in limit position" which appears ~6 seconds after the top auto-stops. I again took out the transmission and removed the metal lid for examination. The switch is again just beginning to touch the raised part of the cam disc, but on the opposite side. This is shown in the photo below.

Third, I held raised the top again, but this time I closed the latch. As usual, the motor turns 1-2 seconds and "Failure convertible top ctrl" message appears. Again, I look inside the transmission and now the switch is several centimeters onto the high side of the cam. This seems wrong. Should the black plastic finger ever ride on the high side of the cam?

Finally, I used a multimeter to test the two switches inside the transmission. Both work fine, opening and closing as I move the black plastic lever back and forth. Moving the black plastic lever downward simulates putting the top down. Moving it upwards simulates putting the top up. I also test the three pins that exit the transmission, just in case there's a short/open on the connector itself.


Top has stopped in fully closed position, but before latching manual overhead latch.

RoadHazard

One more picture: This is after latching the overhead latch. As we can see, the motor and cam have turned counter-clockwise a little bit more. The plastic finger is now up on top of the high part of the cam, not on the rising edge anymore.
The only difference between this photo and the photo above is closing the overhead latch, which causes the electric motor to spin for 1-2 seconds before displaying the "Failure..." message.
Is this normal? Or is this a sign of failure? I can't be sure.


Cam position after closing the manual overhead latch on the windshield header.

loutadd

Dear Roadie,

I am going to compare the closed latched picture to the Pelican photo which is closed position. It seems that the closed latch position in the Pelican photo is also the same as your pre-latch photo you just sent (i.e. the first picture) which indicates to me that your came position should be more to the left low side of cam.

I almost sure that the scribed mark on the gear ring Is probably where your cam plate line was pointing when the gears was changed

loutadd

Follow up to previous message which wasn’t finished.

i believe that the microswitch should stay on low side of cam in pre-latch and latch position that is microswitch out. When micro switch hits high side I think this triggers the error message.

I have marked up your two pictures to show where the cam needs to move to ( the red arrow) depending on which position the cam is presently.

Move to the position shown with red line and latch in both cases. This should work.

RoadHazard

Thanks, but I don't think what you're asking is possible.
The cam disc has an irregular tooth pattern that forces the center hub into a certain position.
The two arrows show how these mate together. I can't rotate the center hub without also rotating the cam. Their relative angle is fixed and they rotate together.


Irregular tooth pattern enforces a fixed angular position between the cam disc and the central hub.