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top stuck in up position - both sides not moving, microswitches fine


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My MY97 top just wouldn't open after closing it and left at a shopping centre today.

The windows drop when unlatched. The handbrake light is on. And the transmission is in park position.

I have read that the point of failure could be the cables or the transmissions. But is that more likely to result in a unilateral failure? As in, the top would try to go down on one side while the other side appears stuck, or is that not the case?

I do hear an initial clicking noise from where the convertible top is if I keep the button depressed. Like an initial push by the motor or a relay activating at the back or something.

I am just trying to get an idea what to expect before I manually drop the top and look around.

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Make sure the latch is unlatched all the way. Put yout finger in the hole where the latch goes and push your finger in and out while you push on the switch.

Pull out the top relay/control unit, gave it a tap, and put it back in. Or swap the relay with another 1997-1999.

If that does not work then you need to see if there is 12 volts to the top motor or if the motor is bad.

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Make sure the latch is unlatched all the way. Put yout finger in the hole where the latch goes and push your finger in and out while you push on the switch.

Pull out the top relay/control unit, gave it a tap, and put it back in. Or swap the relay with another 1997-1999.

If that does not work then you need to see if there is 12 volts to the top motor or if the motor is bad.

Thanks for the quick reply, TP. My Boxster already has problems with central locking and a leaking coolant pump. And now this..... added to the ABS control unit failure and MAF failures and Tiptronic case leak in the last three years....... suffice to say I am a bit depressed.

I don't have another relay handy but I did reinsert and tap the relay. The same problem remains. I have extensively tapped the microswitch from the latch hole, no use.

I can distinctively hear a tick followed by a few seconds of hiss from the back that sounds like the motor is being supplied with electricity and is trying to spin when I keep the convertible switch depressed. There is a corresponding dimming of instrument lights for around 5secs when this happens. But there is no top movement at all. The hissing sound stops in about 5sec and the dimming comes back to full brightness again even tho my finger is still on the convertible switch.

And in amidst my frantic tapping of the convertible top switch, there were two times when the windows just randomly dropped all the way to completely open rather than the 10cm open. Once, only the driver side window completely opened while the passenger side stayed at 10cm. This is after the initial 10cm drop when unlatching.

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Then my guess is that the top motor has given up the ghost.

Is there a way to test that? As in, if I apply direct 12V electrical connection to the motor and see it spin (or not spin)? Where would I find those wires? Someone mentioned a black and green wires but I don't know where they are.

Also, does the top operate up or down because current is applied in either backward or forward directions into the motor or is it mechanically switched somehow?

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I also have a 1997 and here is the connector to the motor. It is a dc motor so it runs in both directions.

Search around in the top/roof section as I think someone went through testing the motor or power to the motor. Right now I do not have the time to look in the shop manual and wiring diagram.

post-4-1172909928_thumb.jpg

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Ok, I got the top down by disconnecting the clips to the clamshell.

I checked the motor. It spins both sides. The cables are not shortened and I have Part No. *01 cables. But when I press the convertible top switch, neither transmission moves! I haven't taken the transmissions apart yet but what could be doing this? I can feel the cables moving (they vibrate) on both sides....

p.s: If people want to know, the motor spins clockwise to lower the top and anticlockwise to raise it.

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Ok, I noticed something strange.

This is what the V arm position is when the top is still fully up, with the clamshell clip disconnected:

post-1432-1172987980_thumb.jpg

This is what the V arm position is when I lowered the roof manually:

post-1432-1172987894_thumb.jpg

post-1432-1172987697_thumb.jpg

Do these seem right? I think the black ball joint lever arm should be on top of the red ball joint lever arm when the top is down. As it is, the top doesn't go down completely because the black ball joint lever arm gets in the way. This would also mean that the resting position of my V arm on the transmission is wrong in that the arm towards the front of the car should be pointing downwards rather than upwards to facilitate the correct movement of the black balljoint lever up, and the red balljoint lever down when the top is being lowered.

Can someone verify if what I say is true?

If so, it would look like that both my transmissions have come off gear at the same time.......... Can I simply push the transmission back in gear by pushing on the V arms or do I need to open up both transmissions to do this?

Edited by Jinster
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Ok, this is becoming like a top repair journal. I figured out that the position of the V arms were incorrect due to over spin of the transmission. I pushed the V arms to as far as possible in the right direction and then pushed the top down button, this took up the V arms and the wound them back into their normal operating arc.

But, after I have hooked up everything, and tried to close the roof again, the V arms being powered by the transmission which is being powered by the motor just kept going as long as I kept my finger on the top down switch even after the top was fully closed. And this resulted in the V arms going over their final position again and internally unhooking the gear teeth.

I am beginning to think that my problem is not with the convertible operating assembly but with whatever mechanism that is meant to stop it from operating once the top is in position.... There must be a mechanism that tells the motor to stop spinning when the top is fully closed so that the transmission doesn't keep disconnecting its own gears by overspinning them beyond the the range of the half moon teeth arc.

Where is this mechanism? Is it the convertible top compartment lid microswitch? I tried to push on that switch but that doesn't stop the motor spinning at all.......

I would appreciate any suggestion people have at this point.

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I think I know what is going on. Don't quote me because it has been many years since it was explained to me by Peter Smith and Bob Grigsby. Peter was the shop foreman at my local Porsche dealer and the Porsch Club of America tech advisor for the Boxster. Bob has a local independent Porsche shop and puts on Boxster tech sessions. They told me what the problem is with a 1997 but I did not pay much attention because of all the local tops we have fixed none had the problem you have.

One end of the cable goes into the motor. The other end is connected to a worm gear inside the transmission. That worm gear is connected to a half moon gear with X amount of teeth. It is like the half moon gears does not have enough teeth on it and you come off the gear as you said. The cable and worm gear are spinning but because the worm gear is not engaged with the half moon gear the V arm does not move.

You need to check with Mark in Sunnyvale on this board as he may know how to fix this situation. If you went to a Porsche shop in my area you would be told to get rid of the old style transmissions that were used 1997-1999 and replaced them with the new style that come out for model year 2000. The new style does not have a half moon gear.

Some time ago I remember a thread on this board about a similar problem. The guy figured out a way to stop the motor from spinning before it came off the gear.

When the clamshell goes down it pushes on the lever on top of the transmission. I think there is a plastic thing on the bottom of the clamshell where it makes contact with the lever. This lever sends a signal to the top relay to let the motor run for a few seconds and then stop. If it does not stop in time then you come off gear. I remember Peter telling me that in the old days he would take a tape on wheel weight and stick it on the bottom of the clamshell where it pushes the lever down. Like a spacer/shim. This would cause the motor to stop a fraction of a second sooner so you would not go off the gear.

I'll look around and see if I can find the prior thread on this issue. In the meantime you need to contact Mark. He has a 1997.

post-4-1172997662_thumb.jpg

post-4-1172997692_thumb.jpg

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Thank you for your continuing support, TP. You are exactly right. The gears keep running until the teeth come off. And I broke a red balljoint while trying to take off one of the V arms to look inside the transmission...... bloody hell.

Building a new control circuit to cut power..... I can get build a circuit using a relay I suppose and mount it somewhere. Jporter's idea of using the V arm to trigger a new microswitch to control a new relay to cut power is a good one.

But I am still looking for a more OEM solution... I know of no one else with a Boxster in Melbourne (Aust) so swapping relays might be a bit difficult.

What I don't understand about the B-pillar microswitch and the microswitch on top of the convertible motor is that are they meant to do and why they are both needed?

It would seem the B-pillar switch is reduntant if there is a switch on the top motor already.

Anyway, I am yet to locate the B-pillar switch. The convertible motor (CTCL) microswitch, meanwhile, doesn't seem to do anything. When the top is moving in mid air (after I hooked up the gears on both sides) and I press down on the CTCL microswitch, nothing happens. The top just keeps moving anyway..... maybe that's where the B-pillar switch come in: both the B-pillar switch and the CTCL switch need to be contacted in order to trigger the final 1sec over-drive of the top....

But Jporter seems to say that his top stops moving midair soon as the CTCL switch is depressed.... It's dark in Melbourne now. So I will have to continue this tomorrow (and put off replacing the coolant pump for another day).

TP, if you got the time, I would be grateful if you could please open your top half way, put some weight on the CTCL microswitch to close it, and then see if you can still move the top by pressing the top down/up dash switch. Coz this doesn't stop the top for me, so I could have a dud switch....

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Ok, no need now, TP.

I have tested out everything via the relay grid. Both switches are working fine.

I finally understand the top mechanism and the role of the microswitches now. Everything works and the motor stops running after the set after-running time. I just need to try to trigger it earlier to prevent overrunning.

Sure wish I figured out everything without breaking that red balljoint. The superglue is still setting. :)

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