Can i manually operate the top on my 1990 911 Cabrioilet? Is so, how?

Question moved from spanish car maker 'Seat' (See-At).
Question edited for clarity. Guessing it is a Volvo, so moved it there. 'Year Make Model' in all question please.

Try, it just be aware of pinch points and get ready to move fast. Also have someone at the ignition key ready to cut power in case anything jams.

Videos that may help

https://www.google.com/search?q=2012+volvo+c70+convertible+top+reset

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Sounds like you have blown a hydraulic hose that operates the top mechanism. You will probably need to find a local mechanic that is experienced with hydraulic operated tops or a dealership. But check you owners manual. Most manufacturers have a manual way of operating the top to allow you to secure it until repairs can be made.

Manually Moving the Folding Top from the Down Position
Important: Allow the system a minimum of four minutes to bleed down pressure after the last cycle.
Manually release the folding top cover latch using the emergency release cable.
Raise the folding top stowage cover.
Manually raise the folding top, holding the 5 bow up.
Manually lower and latch the folding top stowage cover.
Manually unfold the top and latch per normal procedure.

Manually Moving the Folding Top from the Up Position
Important: Allow the system a minimum of four minutes to bleed down pressure after the last cycle.
Manually release header latch per normal operation.
Manually lift front of roof off of the header and raise the #5 bow at the same time.
Manually release the Folding Top Cover latch using the emergency release cable.
Fold the roof down into the well.
Manually close and latch the folding top stowage cover.

Power Folding Top System Components
The power folding top system consists of the following components:
• Folding top control (FTC) module
• Body control module (BCM)
• Folding top control switch
• Serial data communication
• Folding top cover latch actuator
• Folding top cover pull down actuator
• Folding top pump motor with valve manifold
• Position switches and limit switches:
- Pin receiver switch
- Luggage barrier switch
- Folding top cover open switch
- Top open switch
- Top closed switch
- 5 bow raised switch
- 5 bow lowered switch
• Tonneau release relay
• TONNEAU PULL DOWN ACTUATOR Fuse 20 A
• TONNEAU RELEASE Fuse 10 A
• BATT 2 Fuse 40 A
• REAR FOG/ALDL TOP SW Fuse 10 A
• Folding top mechanical components:
- Folding top
- Folding top cover
- Folding top valve 1
- Folding top valve 2
- Folding top valve 3
- Hydraulic lines and cylinders

Folding Top Cover Latch Actuator
The power folding top system includes a folding top cover that is powered open and close by a hydraulic system that is controlled by the FTC module. A power unlatch motor is used to unlatch the folding top cover before the folding top control (FTC) module powers the top cover open. The folding top cover unlatching is requested by the FTC module via class 2 message, but is executed by the body control module (BCM). When requested, the BCM applies battery voltage through the folding top cover release relay control circuit to the tonneau release relay. The relay is energized and battery voltage is applied through the folding top cover release control circuit to the latch actuator. The actuator is energized and the latch releases the folding top cover.

The electronics on this are very complex ,

System Operation
Before any movement of the power folding top is allowed, the folding top control (FTC) module must be aware of the following conditions:
• Unlatch the header. The FTC module reads the pin receiver switch is Inactive.
• The windows must be normalized. Refer to Power Window Reinitialization.
• The ignition must be placed in Accessory or RUN.
• The transmission must be placed in PARK, or with manual transmission, the park brake must be applied.
• Trunk status must not be ajar.
• The luggage barrier must be in place.
• The pump motor temperature must be within the operating range.

After the last cycle of power folding top operation, allow the hydraulic system a minimum of 4 minutes to bleed down before attempting manual operation of the top.
Your best bet take and have it checked for DTC'S - diagnostic trouble codes .
DTC B3666 Rear Tonneau Position Error
DTC B3667 Tonneau Release Circuit
DTC B1011
DTC B1291
DTC B1420
DTC B3602
DTC B3666
DTC B3667
DTC B3670
DTC B3971

check fluid hear pump run

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I’m happy to help further over the phone at https://www.6ya.com/expert/david_6df67de3b14de867

It is possible to have a manually operated top, but the switch is the aftmost on the center console.

Look in hand book for manual operation of roof.
The handle is located side of dash,insert as shown.
Start manual operation
You do not have to do the full opening/closure
After the operation starts and releases rear flap remove handle,
Start car.Check electric operation of roof
This op should have reset it

hello,good day,yes it has a manual opening and closing of your hard top,in your tool kit,one spanner is for your hard top,then read your owner manual how to operate manually,ty

maybe the car has to have the parking brake on. Read the owner manual.
Automatics have to be in Park.
This is to prevent damage to the top when people try to operate while moving.

Just close BOTH the front and back MANUALLY and make sure its in the locked position. (follow the owners manual on how to close it manually). The warning light will go off and the switch will become operational again.
Cheers!