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'98 Convertible Top function (almost) perfect- help needed


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 I was reading a previous post in 2011 made by a member named Fermin who had the same problem with his '99 convertible top dash light staying on all the time even though his top was really working near perfectly, except for that darn red dash light staring at him all the time and the fact that he couldn't drive it in the top open position without having the windows all the way up.  I recently replaced my frame and rebuilt my top too because the previous owner had broken the pot metal where the steel ball connects to the front push rod, rendering the frame useless.  Fermin's problem was that his light stayed on all the time. He had properly synched his transmissions, adjusted his pushrods correctly, replaced his top latch microswitch, checked and adjusted his b-pillar switch and rear motor spring to lid gap and cleaned and adjusted his brake switch.   Apparently the solution was to hold the button down longer at the end of the cycle to get the light to turn off.

Like Fermin, I am totally paranoid about the transmissions overrotating and shearing that pin off and breaking the pot-metal and starting all over on a very expensive project.

My question is: What determines the motor to stop before it might over-rotate? Is it the electrical load on the motor determined by the spring tension?, Or is it an after- run time on the rear microswitch that turns off the convertible dash light?  

I replaced my top latch microswitch and looked and cleaned my brake switch, Still, my dash light stays on and when my top is in the open position (clamshell is completely down and level)  the windows stay dropped about 2.5 inches. In the top-closed position the windows close completely, so I think the new top latch microswitch must be working,  (again the clamshell is tight and level)  but the light still stays on. If I pull the double relay off and put it back on, the light goes off until I open the top, which of course is normal. But when I proceed to completely open the top and the clamshell closes tightly the light continues to stay on. If I continue to push the control button for a brief (1 second) in the down (top down) direction it often reverses the direction of the clamshell and starts to open.  Is my problem a bad rear microswitch or am I just being a wussy and should keep pushing the down button on my dash risking catastrophic destruction of my top that works pretty darn well right now?

post-92309-0-93387400-1414679755.jpg

You can see in the photos the destruction of the ball joint on the frame. My pinky shows the normal right side with intact ball and pot-metal, my index finger shows a broken frame and no place to put that ball joint.

post-92309-0-07743800-1414679777.jpg

Close up shows why I am paranoid.

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I also have a 98 Boxster and the setup is the same on years '97 thru 99.  The light is controlled by the top double relay and what turns off the light is what is thought to be a combination of signals from the lever microswitch on top of the electric motor which is depressed by the clamshell when it closes down on it and the microswitch located on the B pillar.  How those signals and the time lapses received by the double relay is what turns off the light.  Put a 1/4 inch dense foam pad on the underside of the clamshell right above the electric motor lever and see if that does the trick.

 

I have to continue to press the dash switch longer than what feels normal until the light goes out and I wouldn't be afraid to keep pushing.

Edited by kbrandsma
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Hi Paul.

 

I am guessing the last guy broke the metal on the frame because he used a metal joiner rather than the plastic OEM unit - which are known for breaking. And so some people have created the metal ones to prevent it from happening. The thing is, the plastic is designed to be a deliberate weak point in case there is something wrong with the top mechanism - usually dyssynchronised operation (left vs right). This can happen if any of the clips on the clamshell comes lose and things don't move about in the way they are designed to. I imagine if the plastic joiners don't let go, the metal on the frame does, as did in your car with the previous owner.

 

Anyway. There should be no danger of causing the same if you use those plastic joiners. Also, if you "over press", the top transmission should just run out of teeth - again a safety mechanism. The gears inside the top transmission is a half circle rather than a full circle. So over press results in the transmission disabling itself. It's a pain in the arse to resynchronise as you will need two people - one to press the top switch while the other pulls on both top transmissions to get the gears to engage at the same time.

 

I think the light is staying on because the clamshell is bent out of shape over time - you can try "flattening" the clamshell so that when it closes, it pushes down the contact switch earlier. Or you can just use a piece of foam under the clamshell to push on the switch earlier, like kbrandsma suggested.

 

I personally have a piece of foam stuck there and it's been functional for the last 7 years.

Edited by Jinster
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Hi Paul.

 

I am guessing the last guy broke the metal on the frame because he used a metal joiner rather than the plastic OEM unit - which are known for breaking. And so some people have created the metal ones to prevent it from happening. The thing is, the plastic is designed to be a deliberate weak point in case there is something wrong with the top mechanism - usually dyssynchronised operation (left vs right). This can happen if any of the clips on the clamshell comes lose and things don't move about in the way they are designed to. I imagine if the plastic joiners don't let go, the metal on the frame does, as did in your car with the previous owner.

 

Anyway. There should be no danger of causing the same if you use those plastic joiners. Also, if you "over press", the top transmission should just run out of teeth - again a safety mechanism. The gears inside the top transmission is a half circle rather than a full circle. So over press results in the transmission disabling itself. It's a pain in the arse to resynchronise as you will need two people - one to press the top switch while the other pulls on both top transmissions to get the gears to engage at the same time.

 

I think the light is staying on because the clamshell is bent out of shape over time - you can try "flattening" the clamshell so that when it closes, it pushes down the contact switch earlier. Or you can just use a piece of foam under the clamshell to push on the switch earlier, like kbrandsma suggested.

 

I personally have a piece of foam stuck there and it's been functional for the last 7 years.

I had removed my clamshell and put it on a perfectly straight and level workbench.it was less than 1/2 mm out of true at all four corners. I did resort to the foam trick and now in the open (top-down) position the light goes off, however in the closed ( top-up) position the light will still not go off unless I pull the double relay. Do you think it is my b-pillar microswitch lever ?

I'm thinking that the lever is making contact too late and the runtime is too short before the clamshell is tight and top fully closed.

Should I try to bend it forward a bit and see if that works ?

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A few comments on your top operation:

 

1. Your second supposition, wherein you asked whether what makes the light go out is an "after-run time" is correct.  In the "A Version" setup ('97-'99), the after-run time is triggered by the clamshell pressing down on the small black lever microswitch on top of the motor.  

 

2.  Putting a small foam block on the underside of the clamshell triggers (presses down) that switch a split second earlier and that turns off the motor and the dashboard light a little bit earlier in the rotation of the V-levers on the transmissions.

 

3.  Jinster is also right on the money regarding the "sacrificial" nature of the front pushrods (specifically the plastic ball cups on those pushrods).  You can only risk breaking the lug as shown in your photo with the ill-advised "custom" metal ball cups or if the small, thin (14mm?) hexagon end of the lug is not securely tightened onto the frame.

 

4.  The B-pillar microswitch serves mostly to reverse the direction of the rotation of the V-levers by reversing the direction of the spinning of the electric motor.

 

5.  If your top appears to be retracting (i.e. the leading edge of the top pulls away from the top horizontal edge of the windshield frame) before it has completed the cycle, the overall length of your pushrods must be adjusted to the optimal length.  The optimal length will result in the leading edge of the top meeting the top horizontal edge of the windshield frame at the completion of the cycle.

 

Don't be afraid to keep your finger on the switch.  Instead, buy a couple of spare plastic ball cups.  There is a guy in Belgium or the Netherlands who had them manufactured and he may still be selling them.

 

Regards, Maurice.

Edited by 1schoir
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A few comments on your top operation:

 

 

2.  Putting a small foam block on the underside of the clamshell triggers (presses down) that switch a split second earlier and that turns off the motor and the dashboard light a little bit earlier in the rotation of the V-levers on the transmissions.

 

4.  The B-pillar microswitch serves mostly to reverse the direction of the rotation of the V-levers by reversing the direction of the spinning of the electric motor.

 

5.  If your top appears to be retracting (i.e. the leading edge of the top pulls away from the top horizontal edge of the windshield frame) before it has completed the cycle, the overall length of your pushrods must be adjusted to the optimal length.  The optimal length will result in the leading edge of the top meeting the top horizontal edge of the windshield frame at the completion of the cycle.

 

 

Regards, Maurice.

.

Thanks the replies,

I did the foam trick and the rear motor switch turns off the light only in the top down (open position), but not in the top up (closed position). In the top open position the b-pillar switch is open, right ?

When closing the top, the convertible top frame meets the windshield frame exactly and snugly when the clam shell is tight and sealed even when pressing the motor for another 1-2 seconds, so I think I have the pushrods in their optimal position, however the dash light still stays on. If I lock the top down, the windows will roll up, but the dash light still stays on.

Why do the the windows roll up but the dash light stay on ?

Does the front microswitch have two separate signals?

One that controls the windows and one that turns off the light ?

The mechanism looks too simple for that. If makes more sense to me that the b-pillar microswitch is in the closed position, with the top in the nearly closed position, that the relay is now waiting for two signals: one from the closing of the clamshell, then waiting for the latch to close.

If that is the case, perhaps I have a short in the b-pillar wiring or the second signal wiring in the top latch microswitch.

Does any one have circuit wiring diagram that elucidates the relationship between the switches and relays ?

It is amazing how one red light on your dash can make a Boxster owner nutty!!!

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  • 2 weeks later...

Finally got the dash light to go off with top in the closed position thanks to the tip Maurice gave. Following the microswitch trouble shooting guide, there was no signal from terminal 29 ( the b-pillar microswitch). The switch has a simple two wire quick disconnect located at the base of the roll bar. Using a voltmeter, I tested the switch and it worked fine when I manually closed it. I checked the two wires going to the relay carrier. The brown one is a ground, and the brown with green stripe goes to terminal 29 on the carrier. The wire showed good continuity. . I took the switch out and compared it to my old one. What I found was that the spring was a bit weaker than my old one and was not making contact in the same position or perhaps with the same force. I put a little more bend in the spring and re-installed it and viola! No more stupid red light staring at me .
post-92309-0-56743400-1416800011.jpg this is before.

post-92309-0-35345000-1416800072.jpgI "added" about 2mm to the bend. It's pretty subtle, so take a second look at both pictures and compare. It was enough difference to close the switch ( and turn off the light) when I put it back into the car and closed the top.

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