Cab top goes up and down... won't latch

[Bhom]

I'm taking care of a friend's 1988 cabrio, and the top has been working beautifully, until now it isn't. The motor seems to work, it goes all the way up and down, except when it gets to the very last bit when closing, it just doesn't latch.

I know that there is a manual override with the screw holes, and some have reported that doing the manual override once fixed the problem. I'm finding it difficult to get a screwdriver in and seated. Would be easier if I could pull off the surrounding plastic trim, but don't want to break it in doing so. Can anyone tell me which side is the right one to pull on to get it off?

Beyond that, if manual latch doesn't reset, how do I look deeper into this problem?

Thanks for any advice!!

[MTN930]

Your post doesn't indicate whether or not you hear the latch motors or not. If you don't hear the latch motors, perhaps there is an electrical issue. If you hear the latch motors running, the gears w/in the latch may be stripped (would be odd to have both stripped at the same time).

I had the same issue, on an '86 not an '88, and found out that the initial issue was electrical, then the passenger side motor had stripped gears (which were really easy to replace).

You may also want to review this post: https://forums.pelicanparts.com/porsche-911-technical-forum/1041351-1988-911-cab-top-wont-latch-electric.html

[mysocal911]

Originally Posted by Bhom

I'm taking care of a friend's 1988 cabrio, and the top has been working beautifully, until now it isn't. The motor seems to work, it goes all the way up and down, except when it gets to the very last bit when closing, it just doesn't latch.

I know that there is a manual override with the screw holes, and some have reported that doing the manual override once fixed the problem. I'm finding it difficult to get a screwdriver in and seated. Would be easier if I could pull off the surrounding plastic trim, but don't want to break it in doing so. Can anyone tell me which side is the right one to pull on to get it off?

Beyond that, if manual latch doesn't reset, how do I look deeper into this problem?

Thanks for any advice!!

Read here under Porsche Cab Top; https://www.systemsc.com/problems.htm

[Bhom]

Thanks, both of you!

Re: the latch motor, it wasn't clear to me that I could hear a motor other than the one that raises/lowers the frame of the top. Is the latch motor something I should hear *after* the main motor completes bringing the top to near-closed position, or does it start running as the latches near the frame?

(i.e. I should hear the normal motor then the latch motor after, or I should be hearing the latch motor together with the normal motor at the end of motion?)

[Dan J]

Probably the micro switches next to the latch motors
Pretty simple to check with an ohm meter

[boyt911sc]

Dan,

Could you be kind to elaborate about the switch that operates the latching mechanism? I have been trying to diagnose a very similar problem like the OP is having without any luck. Your experience and suggestion could direct us to a solution. Thanks.

Tony

[proporsche]

Originally Posted by Dan J

Probably the micro switches next to the latch motors
Pretty simple to check with an ohm meter

^^^^^^^^^^^^^^this^^^^^^^^^^^^^^
Also check the closing micro switches for each side of the closing motor-behind the side panels .If they do not close(touch the little arm of the switch) the signal is not forwarded to the switches on the windshield.
On Pet diagram no17.



Also have you tried to close the top latches manually -there is a slot for this tool ..
one of these Allen tools is for it.Once you have it closed open it all the way and try close it again..report how it is...
Ivan
It has been 19 years since i worked on the top so i hope i am a little right;-)

[mysocal911]

Originally Posted by Bhom

Thanks, both of you!

Re: the latch motor, it wasn't clear to me that I could hear a motor other than the one that raises/lowers the frame of the top. Is the latch motor something I should hear *after* the main motor completes bringing the top to near-closed position, or does it start running as the latches near the frame?

Yes! It's micro-switches that cause the locking motors to operate.

Originally Posted by Bhom

(i.e. I should hear the normal motor then the latch motor after, or I should be hearing the latch motor together with the normal motor at the end of motion?)

Put the top in the vertical position, and with the help of someone holding & releasing the micro-switches, the system can be easily tested & evaluated.

The most common problem is the cab top ECU! The company referenced in post #3 repairs the ECU.

[MTN930]

To answer your two questions, yes. The latch motors run after the top has been fully extended up and the actual latches have been slotted into the catches above the windshield. There is a micro-switch in each of the two latches which is triggered once the top has been put fully up and the latches fall into the slot.

===============================

Originally Posted by Bhom

Thanks, both of you!

Re: the latch motor, it wasn't clear to me that I could hear a motor other than the one that raises/lowers the frame of the top. Is the latch motor something I should hear *after* the main motor completes bringing the top to near-closed position, or does it start running as the latches near the frame?

(i.e. I should hear the normal motor then the latch motor after, or I should be hearing the latch motor together with the normal motor at the end of motion?)

[MTN930]

@proporsche - The micro-switches are adjacent to the latching mechanism. Here is a diagram, see part #6 and #7.

[mysocal911]

Originally Posted by MTN930

To answer your two questions, yes. The latch motors run after the top has been fully extended up and the actual latches have been slotted into the catches above the windshield. There is a micro-switch in each of the two latches which is triggered once the top has been put fully up and the latches fall into the slot.

===============================

No, the two external micro-switches are in the TOP itself, which triggers the locking motor function.

Yes, the two latch locking motors each have an internal micro-switch, to indicate when the locking function is completed.

The system is EXTREMELY simple and well designed!

[freddy67]

Only in a '911 cabrio can “the top won’t latch” turn into an ECU deep-dive and a full-blown electrical safari. Gotta love these cars.

[mysocal911]

See how simple it is;



Watch the relays, they will "tell" you what the Cab TOP ECU is doing.

[Bhom]

Originally Posted by mysocal911

Yes! It's micro-switches that cause the locking motors to operate.



Put the top in the vertical position, and with the help of someone holding & releasing the micro-switches, the system can be easily tested & evaluated.

The most common problem is the cab top ECU! The company referenced in post #3 repairs the ECU.

Thank you!!

When you say vertical position, you mean like halfway open with the latches pointing up into the air?

[proporsche]

Originally Posted by MTN930

@proporsche - The micro-switches are adjacent to the latching mechanism. Here is a diagram, see part #6 and #7.

i am actually mention the switches by the arms..if they are not engaged the top will not not close,not the switches by the motors

Ivan

[mysocal911]

Originally Posted by Bhom

Thank you!!

When you say vertical position, you mean like halfway open with the latches pointing up into the air?

Yes! That's the ideal position to put the top into for testing. You and a helper (controlling the limit switches) can test all the functions.
The switches by the rear arms have little effect other than stopping the top's movement (limiting).

[Bhom]

Thanks for all of the information so far, everyone.

So, I've found the limit switches under the passenger side panel. What I've been able to determine is that they seem to work: when neither switch is pushed down, the motor will run when I hit the raise/lower switch. If I hit the closed limit switch (which as I understand is never supposed to be hit unless the top accidentally goes too far), the motor will cut, same if I hit the other limit switch.

I can not get the latch motor to run, even with the latch microswitches pushed down.

What further diagnosis can I do? Is there some sort of synchronization procedure or state that I have to get the system into?

[mysocal911]

Originally Posted by Bhom

Thanks for all of the information so far, everyone.

So, I've found the limit switches under the passenger side panel. What I've been able to determine is that they seem to work: when neither switch is pushed down, the motor will run when I hit the raise/lower switch. If I hit the closed limit switch (which as I understand is never supposed to be hit unless the top accidentally goes too far), the motor will cut, same if I hit the other limit switch.

I can not get the latch motor to run, even with the latch microswitches pushed down.

What further diagnosis can I do? Is there some sort of synchronization procedure or state that I have to get the system into?

Watch the right two relays in post #13. The locking relays should close when the micro-switches close. If not, you have a bad cab top ECU.
There's NO sync procedure!

Consider sending the ECU to the reference in post #3.

[Bhom]

Okay. I can confirm that the relay on the ECU clicks when I hit the top up/down switch. But I don't hear a click from any relay in the ECU when I press the latch microswitches. Is this a smoking gun that it's the cab top ECU?

Another question: what is it that stops the motor when the top gets to the latching point? Is it the latch microswitches? Because the top closing limit switch is only meant to be triggered as a fail safe if the latch microswitches don't, right?

[mysocal911]

Have Pelican Parts order you a new ECU!