993 Cab - Convertible Top issue

[FLY993]

Here's one: The top on my 993 cab is up. Standard procedure to electronically lower top is : put ignition key in position "2"; Put handbrake on (obviosly when car is in stationery position!); press the rocker switch. What happens? I hear the rotors behind me activating; hear no rotors activated on the front; after several seconds with switch depressed hear a minor pop (the 30A fuse blown) then the central warning light along with conv.top light come on, as they should . I have tried this several times resulting in the 30A fuse blowing.Could this be front rotor problem?

As always thanks.







"The only risk in life is not taking one - Live Fully" - JPS

[expat]

To start, I assume you mean the roof is open (fully retracted rewards) when you say the roof is 'up'.

Originally posted by FLY993
I hear the rotors behind me activating; hear no rotors activated on the front;

Ok, Im not so versed on the 993 tops but will try to help..

The rotors at the back - do you mean the motors?

What rotors on the front? Do you mean the locking motors?

Are you trying to return the roof to the closed position but all you hear are the rear motors turning but no action from the roof itself? If so, this sounds like the bolts have backed off and the gears arent engaging. Not sure how this would manifest itself in fuses blowing unless your holding the toggle switch down for a long time and this is causing resistance in the line that is heating up the wires and leading to a blown fuse.

Alternatively the motors aren't turning freely and getting stalled somehow therefore blowing the fuse.

Anything been done to the car recently in the area of the roof? Cleaning microswitches as an example?

Does on side seem to work marginally and the other not? Maybe broken drive cable?

Any more info you can provide?

[FLY993]

No, the roof is closed i.e I am trying to open the top. The tech terms for the parts may not be correct but , yes, what I mean is that i am hearing the motors at the back activate; there is moderate tension on the top as if it wants to open; but I hear nothing happening in the front (the locking motors). The only recent thing done to the car is that Porsche completed the engine electrical harness recall. Something else is that i amhearing a cracking sound cominf from the low rear right of the car..turns out it is
a spark on the mounting (?). Thanks

[expat]

Originally posted by FLY993
Something else is that i amhearing a cracking sound cominf from the low rear right of the car..turns out it is
a spark on the mounting (?). Thanks

spark where?

Back to the top -

I would have though it strange for your rear motors to be operating before the front locks have released.

On my 87, I toggle the switch, the locking motors release the locking wheels (on the rotating arm) on the top of windscreen frame and once they have completely retracted, the rear motors begin to actuate pulling the roof back until the microswitches contact, telling to motors to stop winding.

I dont understand why you can hear the motors at the rear with the roof still locked down!

Can you see the locking motor actuating arm? Maybe they have already released and something is stopping the roof from retracting. Thats then causing the motors to heat up and blow the fuse.

[expat]

Dumb question but... you are doing this on a flat surface arent you?

If the car is up on a kerb the twisting effect will (possibly) stop the roof from retracting as the locating pins on one side might become trapped in their recess.

[FLY993]

Yes, I am doing this a flat surface. Good point on the front locks perhaps already being released - I think that could be it: That would explain why I hear nothing in the front (locks already released); then rear motors begin to actuate; then minor tension to top; no movement;
finally fuse blows. Regarding possible obstruction, I have a windstop which is positioned on the top , just behind front seats...maybe i should take this out?

[FLY993]

the sparking seems to be coming from a spark plug wire , right set.

[expat]

Hmmmm...you'll probably give your car a new lease of life with some new leads, pickup a cylinder

Can you see the locking motors on the front. You might be able to peek up there and see their location. Even with the roof locked down you may be able to pry the cover back enough to have a look. On my 87 i can actually unscrew two screws and remove the cover to the motors.

If you can establish the motors are in fact released (on the front screen), I would try opening the roof with some help by pushing upwards on the leading edge. It might just be jammed a little on the locating pins either side of the roof.

Good luck. let us know how it turns out.

[Speedster94]

Disconnect the Motors and open the Top by Hand . Dont let the Motors pull the Top abgainst the Locks in Front . This will create major Damage to the Top and the Windshield Frame .
Harald

[FLY993]

Thanks for the advice guys. I'll keep you posted.

[expat]

Dont know whether its possible but it would be cool to either
a) double post this thread on the 964/993 Board
b) move it over to that board

Helps people in the future you know.

Cheers
mark

[FLY993]

Last night I took the cover off (two screws) that covers the front motors and confrimed that they were indeed not releasing. So , to recap, what was happening was -when pressing rocker switch - rear motors were pulling but front motors were not releasing which blew the 30A fuse.

I proceeded to unlock top locking motors manually with flathead screwdriver . One caveat here when doing this: make sure that both motors are FULLY released before hitting the rocker switch again. The mechanism of the rear motors are strong enough to cause serious damage to either your windshield frame (upper) or the front lock that is not fully released or both! Anyway, to conclude, this was indeed the problem to my issue (see postings) and both Mark (expathk) and Harald (speedster94) were spot on and helpful. Thanks again.

I will be posting my car on Owner's Gallery shortly ..please take a look.

James

Black P993Cab - uprated
Black BMW325iCab - Commute Car
Rosso Red Lancia Integrale - Sold, but sorely missed.

[expat]

Good stuff James,

So is it once again operating properly?

I still dont quite understand why the rear motors were operating though. As I recall they should not start operating until they recieve the message from the control module that the front locks have released.

Any thoughts? Harald?

[FLY993]

Yep, the top seems to be ok now. I've operated it several times and, fingers crossed, all is fine.