Calibrating Convertible top

I replaced the left cylinder due to a hydraulic fluid leak on my 2003 C4. I topped off the fluid in the pump reservoir connected the hydraulic lines then bleeding all the air out of the hydraulic system BEFORE I installed the hydraulic cylinder and installed the new cylinder leaving the top in the same "service position" as when I removed it. The top worked for a couple of cycles but then would not close fully and wouldn't open. I had to do a emergency convertible top closing as specified in the Service manual. Now top stopped working altogether. The pump is not getting turned on by the control unit. Before I can do a calibration the factory service manual says certain criteria must be met. The first two are: #1 The convertible top latch must be repaired after an emergency operation" and #2. The convertible top compartment lid drive must be repaired after an emergency operation . They reference Service no. 61 01 41 in the service manual but I apparently don't have those pages. They both were working fine fore I replaced the cylinder. Is there some mechanical initialization that needs to be performed before attempting the calibration? I read in the Bentley manual the position potentiometer must be set to 6.3Kohms I believe with the rear top cover open. But that will not even attempt to open now when depressing the open switch on the panel.

Do you have any fault codes present?

"emergency" operation really screws up the works of the convertible top system. Everything gets out of sync. The linkage that drives the clamshell (compartment lid) can get sheared off and need to be replaced. I'm not sure what gets damaged with the convertible top latch... First thing I'd do is inspect the linkage from the clamshell drive motor. Here's how to access it: https://www.pelicanparts.com/techart..._Mechanism.htm It's been a few years, but the linkage connects the motor to the rack-and-pinon clamshell drive system. Check for a sheared drive pin of some type. Next, figure out if the convertible top latch has been damaged. I don't know much about that part. Finally, get it calibrated. The potentiometer on the clamshell drive needs to get sync'd up with all the microswitches and the motronic controller box. Good luck. ps. It would have to be a DIRE emergency for me to use the "manual" cab top operation sequence.

Did you double check that the hydraulic valve you had to open to do the manual close of the top is fully closed? I had the same issue after doing an emergency close of the top and found that I hadn't closed the hydraulic valve and so the pump wouldn't start. My car is a 2001 C2 Cab.

Thank you all for responding. Sorry it took so long to respond but I've been busy moving my daughter halfway across the country(NJ to MN). Finally got the Duratech scanner had some time to connect it. It has limited convertible top functionality. Basically only read and reset codes and perform a calibration. I had a code 5 stored which is a timeout on one of the motors. As I said in my first post the top is closed. After resetting the error and trying to perform a calibration the windows rolled down, the hydraulic pump activated for a few seconds and the front latch tighened a bit both due to the latch motor as well as the hydraulic pressure generated. Then everything stopped. Code 5 appeared again. Resetting it and trying a calibration again resulted in the pump running for a few seconds in the close direction and nothing else happening. Again code 5 appeared probably to to the pump running and no top motion detected - because the top is fully closed. The rear clam shell is fully closed and latched and does not try to open when initiating the calibration and its microswitch is activated in the latched pposition. So it seems like initiatiating a calibration only tries to close the top. The manual closing procedure leaves the side flaps up and my next thing to try is putting them down manually and seeing if initiating a calibration tries to actually open the top. After that it will be manually opening the top to its service position and start checking the status of the microswitches as well as the position potentiometers. As someone posted, a manual closing my damage the clam shell motor/drive. I can manually open and close the clamshell with a hex allen key inserted into the motor from behind the rear seat. I guess I could apply power directly to it an see if it activates the drive motor and see if the potentiometer rsistance is changing. The question I have now is what should be the status of the three microswitches in the front latch mechanism. There is also a fouth switch in the windshield frame. Any other suggestions will be appreciated. Someone already offered to send me the missing pages form section 61 of my service manual so I am hoping that will help me out. Thanks in advance. P.S Yes I closed the valve on the hydraulic pump.

After looking at the complete section 61 I realized I need to, as the Porsche service manual refers to it as, "repair" both the top latch mechanism snf the rear cover motor after an emergency top actuation. According to the service manual it is really just a proper initialization procedure to make sure they are both in the expected condition the control unit expects them to be in before attemting a calibration. It is outlined fairly clearly.

I want to close this thread since I started it. I got the convertible top working properly. Once I had the complete section 61 of the service manual I realized that the convertible top position sensing potentiometer is actually connected to the left actuator. I had thought it was somehow mounted to the convertible top frame. When I replaced the left actuator I didn't remove the entire left rear interior panel but just the left rear speaker to access the lower actuator attach point and I didn't see the potentiometer was actually connected to the guide pin of the actuator. Upon correcting that I no longer was receiving the time out error code 5 and I was able to calibrate the top with my duratec. As I mentioned in my previous post, after I had the complete service maual section I found out that the front latch and rear cover drive had to be re-initialized after performing an emergency top close. Not difficult but this something NOT mentioned anywhere else such as the Bentley manual or the otherwise detailed Pelican Parts convertible top trouble shooting guide. Re-initializing the rear cover drive is relatively easy and seems counter intuitive but it works getting the position potentiometer on the motor gearbox working properly. The front latch assembly is more involved as it requires it to be removed from the top and requires a relatively high current (>3 amps) 9v power supply. The front latch is mechanically complex but suffice to say that if you use the hex key to rachet the front hook in or out it WILL need to be re-initialized. The good thing is that there are three mcroswitches in it an when removed they are easy to check for proper operation. A word of warning. There is a "contact bar" protruding from the front of the latch assembly that actuates a microswitch telling the control unit that the top has reached the windshield frame. It is relatively fragile and easy to break when re-installing the latch mechanism since you are working up side down. That happpened to me and I had to partially disassemble the mechanism to repair the contact bar since it is not available separately and I didn't want to buy a whole new latch assembly. I used Locktite 380 high impact cyanoacrylate. The Duratec calibration was quick as it only moved the top from the service position to fully open. I thought it would've also moved it to the fully closed position. Thanks to several members which provided me with the factory service manuals to make my job easier. The After Sales Training manuals are a treasure trove of detailed operation information for almost all the systems on the car. Great forum, great people.

Mind forwarding me the factory service manuals? I am having a problem with my 99 cab, and as you say, the Bentley manual doesn't cover it. My top works, but not the clamshell, so I think I need to recalibrate the clamshell. That's the only part I ever did manually. Thanks.

Anybody have the information for initializing the top for calibration? I also replaced the pistons and have to calibrate. Currently mine will not fully open

Here is Section 61 - repairing soft top components and calibration. I think the latest version of Durametric will perform the calibration, otherwise Porsche PIWIS is necessary.

Thanks. You, sir, Rock M

Makoto0406 how about a follow-up post on what happened?

My in-laws have been in town so I haven't been able to get on it. they left today. I've been reading a couple other how too as well. Looks like I need to get the resistance at the potentiometer to 6.2k ohms. I'm hoping to be able to give it a shot this weekend (I'm working so it's 50/50). Regardless of what happens I'll give an update. M

Thanks. I'm looking forward to it. I'm thinking of getting a Durametric as well and want to see how it worked for you. I confirmed with Durametric that the latest version does provide synchronization.

I wish I was better versed in the mechanics of the top. I had my top replaced, and before it was working perfectly. Now, the top looks great but the latch tries to engage before it gets to the place where it should, so I have to pull it down with my arm and get it to latch that way. My install guy claims it is because the fabric is so tight, and it will stretch and start to work as it should. But it's been a year and nothing has changed...

How are you guys getting the potentiometer at 6.2K. The instructions have the potentiometer off the motor and it’s not intuitive how to get it off. also the clamshell is supposed to be closed for the calibration. I tried to pull it shut by the brake As instructed but it does not move at all, the car is literally sinking down in the suspension M

Wish I could help you with this but I'm learning as well as I go along. From the diagrams that I have seen it looks like a screw (maybe allen key) goes from the Pot into the gear drive???? I have read the Section 61 and have to tell you it may take a few more readings for it to be clearer. Think we could use some help from more knowlegeable folks. BTW I think you have done wonderfully well so far.

I sort of figured out the resistance. You can adjust the resistance by 1. Pulling the motor from the drive unit 2. Removing the drive shaft from the motor 3 reverse the shaft into the potentiometer and turn to adjust. You can open and close the compartment easily by hand if the motor is removed or by tightening the screw in the motor shaft all the way (which pulls the shaft from the motor) I tried to run a calibration but it didn't work. I had to go to work so I couldn't go any deeper. I'm going to try again with the top in the open position and the clamshell closed at the start which seems to be what the directions indicate. I don't have a power supply to get the latch lined up and that could certainly be a issue. M

Well I went through the whole "repairing " the latch and clamshell procedure and it didn’t work. Still throwing the 4- rear cover potentiometer 5- timeout 6- calibration required error codes. One of the instructions mentions calibrating the voltage at pot 2. Does anybody know how to do this? Anything I’m missing? thanks M

Hello Makoto0406 Sorry, I've had personal issues lately and have not had a chance to "play" with my 996. I got my Duramatic last night so I am just starting in on the procedures. It is interesting to compare reports. Mine reads as follows: 3 Potentiometer fault covertble top 5 Maximum time exceeded (timeout) 6 Calibration required My interpretation is that we both have prolems with potentiometers, you with the "cover pot" and me with the "top" pot. Remember there are two pots. What I don't know is if they have to be replaced or just "calibrated". The report says calibration required. I think that means the pot has to be calibrated and if it can't be it needs to be replaced. Again, this is my interpretation. If anyone knows better please correct me.

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Did you recently replace the pistons? From my prior research the most common "top" potentiometer problem is people fail to attach the potentiometer for the top to the guide bolt of the piston. You can see the top potentiometer on the drivers side. It looks like a loop. The guide pin needs to go through the loop. Otherwise the potentiometer does not move consistently when the top is operated M

As a matter of fact I had both pistons rebuilt because the driver's side was leaking. The guy who rebuilt them was very clear in his instructions about making sure the potentiometer was connected properly. I checked the potentiometer yesterday with an ohm meter and it shows that ohms vary depending on what position it is in which to me indicates that it is working of a fashion. I also measure that it is getting just over 10 volts. Wish I could find out what normal is. How are you progressing with yours?

You also asked about calculating voltage at Pot 2. From what I have read, I think you would need the factory testor 9636 and pin template 9636 to do this. I am currently in "reading mode" and trying to get as much info as I can. If I make any discoveries, I will let you know.

Just finished checking the side potentiometer with ohm meter. 3.9 ohms not the 6.3 ohms required, so I will ordering a new one tomorrow. There does not seem to be any way to adjust or calibrate it.

Glad you found your issue. Let me know how the install goes M

The new potentiometer arrived last night so I proceeded to install it this morning. The top now goes up and down and locks at the front. However, the clamshell does not budge. It was working before the other pot failed. I'm begining to think that this car is cursed. The strange thing is that the calibration works on the top but there are no codes reported for the clamshell like there are in your case. Any ideas?

Did you hear the motor for the clamshell? When I calibrate the top using the durametric the clamshell opens first. If you didn’t hear the motor activate I’d guess it’s a 1) bad connection 2) the motor is broken if you heard the motor run or the motor ran a little bit than stopped I’d look to make sure you didn’t leave the screw that goes into the potentiometer from the interior side too tight (I had similar symptoms to yours when I left it screwed all the way in). Unscrew it all way than screw-in 3 rotations. my car is getting the IMS done right now so I can’t take pictures. M

I did not hear the clamshell motor, but I could see the clamshell shuttering as if it was trying to do something. Thanks for the suggestion about backing off the screw. I am sure that I tightened it too much. I did check the ohms and can only get it up to 3.9k, which is the same as I got for the top potentiometer. Perhaps I have a problem with my ohm meter. I'll see what I can accomplish to day.. Mike

Thank you Makoto! I backed off the screw as you suggested, and now everything works. That investment in the Duramatic has paid off. My local Porsche dealer wanted $2,400 to fix the top and $1,600 to fix the rear window, because he said the top would not work without the window working. Now what can we do to get your top working? What year is your car?

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Hi everyone, I'd like to get this topic resurrected for my restoration project. I've got a similar problem, I've bought a replacement front lock (that apparently needs to be calibrated), installed it. Now the clamshell motor sounds like it's activating but stops after a few seconds with no movement. I'm going to follow the instructions from the workshop manual and see if I make progress. I'd appreciate any more insight if you have any tips.

this is super useful. my clamshell does not go down when i open the soft top and there is an inch or 2 left, where do you think this could come from?

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So either the microswitches are faulty on the flaps or they need to be calibrated because the clamshell step is waiting for them to go down before closing. Otherwise it'll just sit there.

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Hello gwroclaw, First at all thank you for your write up. I know is an old discussion but I was hoping you might be able to help me. I am woring on a 2003 911 where I just replaced the 2 hydraulic cylinders. After installation the top did not work and I tried to do the procedure but without the calibration portion because I do not have a durametric. Now when I activate the system to close or open it looks like is pulling only from one side and it moves unevenly. Do you think it is a matter of calibration? if so, give that I am local to NJ do you think we could try to do the calibration? Thank you in advance for your help. Matt

Hello gwroclaw, First at all thank you for your write up. I know is an old discussion but I was hoping you might be able to help me. I am woring on a 2003 911 where I just replaced the 2 hydraulic cylinders. After installation the top did not work and I tried to do the procedure but without the calibration portion because I do not have a durametric. Now when I activate the system to close or open it looks like is pulling only from one side and it moves unevenly. Do you think it is a matter of calibration? if so, give that I am local to NJ do you think we could try to do the calibration? Thank you in advance for your help. Matt what is pulling on one side only? Are you talking about the rear compartment lid (aka clamshell), or are you referring to the top itself?

Hold my beer... You must rebuild both rams at the same time, or your have the issue you're describing. Also, there may be air in the line and the pump's bleeder screw can be access from behind the right rear passenger cushion and panel. You'll need a long extension. Check out my video on this specific topic. Here I'll even share the video here, at the exact moment I discuss this: You Tube

Looking for some help folks, the clamshell is not opening. I have read all of the posts related to top issues and they've been extremely helpful and have allowed me to get to this point. The car in question is a 2004 911 4S Cabriolet. The LH top cylinder was leaking, that was replaced. Yes, the pot is in line with the pin on the cylinder and is in place. Prior to the repair, I did have to use the emergency open method to service the top. The latch (opens and closes) and pot (6.2) at the clamshell motor are all within spec. During repairs I found the RH flap motor faulty, that was replaced. I purchased a Durametric to calibrate the top - but it has not gone thru any cycles of opening or closing it, so I think it is just "timing out". If the clamshell is manually opened (with a wrench), then by using the button on the dash, the top will go down, stow away, the flaps will come up, and clamshell closes . Then, again with the button on the dash, I can close the top, the flaps go down, top goes up, and clamshell closes(again ONLY if I manually open it) So I know everything is working - except the clamshell will NOT open! However, calibration will not take place and the clamshell will not open up to permit the top to open and fold into the boot. Using a test light, the motor is receiving power long enough to start to unlatch the clamshell, then power ceases. This leads me to believe something is still out of sync and the Durametric will not calibrate it. The only faults that shows up is after 5 attempts and I clear that often. There is also a fault showing in the instrument cluster, fault 9914 will not clear out. I am not sure if this is impacting the calibration? Any help is greatly appreciated!

I also demonstrate the clamshell motor and how to test it. I believe what I had to do was manually close it and perform a few steps to get everything in sync, like rethreading the clamshell bolt and bleeding off the hydraulic pump for the top. Also, you must rebuild BOTH rams at the same time. Not one at a time. If pressure is not even you'll have issues too. This system is very finicky about everything.

I wondered if I could get advice on my convertible top issue on this thread: I have a 2002 996 Carrera 4 convertible, and on the way back from my dealership for a " road safety check " , my convertible top would not close all the way. It stops 2 inches short of the A pillar and then tries to close the latch. This has never happened before. Do I need to go to the dealership to have the top re-calibrated?

Sounds like a calibration issue. Either the potentiometer or one of the limit switches thinks the top is all the way closed when it is not.

Check the flaps attached the sides of the clamshell. They sometimes get in the way of it closing. You should be able to see them from your side mirrors. I'm not referring to the motorized flaps, but rather spring loaded ones that cover the gap between the clamshell and the top when it's retracted.

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Sorry to resurrect this, but I went through the repair of the hydraulic rams on my '99 c4 cab sometime ago. Top has been working fine since, with one problem. The clamshell as it swings open does not swing all the way, about 95% I'd say. As the roof is lowered and stacked, and the clamshell tries to close, it does the same thing here, and closes about 95% of the way, so that it does not sit completely flush at the end of the roof lowering cycle. The light on the dash is also illuminated. Any thoughts on what may be the possible culprit? Is it a microswitch issue or maybe the clamshell drive allen screw can be used to adjust it? I'm afraid to touch it in case it triggers a need to re-calibrate.

My guess is gunk in the sliders that are driven by the rear bowden cable mechanism. If enough gunk builds up, it can damage the clamshell hinge arms and bowden (bicycle type) cables. Just a guess though. Look at post#17 here: https://rennlist.com/forums/996-foru...more-pics.html

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Thanks so much for the reply! I have followed your entire thread and videos, that's how I learnt of the emergency clamshell Allen. Those were awesome! So I am surmising that the "alignment' with the drive pin is my problem. The sliders do appear to be gunk free on visual inspection. In post #17 in the other thread, when you say you "aligned" the drive pin, how did you do that? By turning the Allen screw behind the motor via the rear seats? Or by moving the clamshell by hand? When I put the roof back up, the clamshell goes back into closed position perfectly flush with body. It's only when I lower the roof that it doesn't fully retract or close. ​​​​​ ​​​​​ ​​​​ ​​​​​ ​​​​​​ ​​ ​​​

My issue was caused by the gunk in the slider. This resulted in: Bending the L-shaped bracket Damaging the bowden cable drive that moves the clamshell Braking one of the hinges. So, for me, I had to bend the l-shaped bracket back to its normal shape in addition to the other repairs. It looks to me as if your slider isn't all the way back. My guess is that the clamshell is hitting something, preventing it from closing all the way, and preventing the slider from going all the way back. Is the top fully folded down? Are the clamshell latches (3 of them) functioning properly? Something else binding? It's difficult to guess without seeing it.

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Ohh I see. Nothing seems bent out of shape on my end so I think it's all aligned. This prompts me to look at the slider movement, which is affected as I understand by turning the screw behind the clamshell drive motor. However, since you didn't mention the screw yet, I'm not touching it. 😅 As far as my inspection goes, Bowden cable seems intact. The cables are routed neatly and don't seem to be binding. Roof folds as normal too as far as I can tell. ​​​​​ Another thing that just occurred to me, when do the hinges kick in? It is after the roof is fully lowered and clamshell closes properly and hits the Microswitch right? Or are the hinges supposed to pull the clamshell down the final 5% when I lower the roof? ​​​​​ ​​​​​​ ​​ ​​​​ ​​​​ ​​ ​​​ ​​​

I wouldn't mess with the manual operation drive motor "screw" unless you truly understand what's wrong. Something is preventing the clamshell from fully closing. Forcing it will only make it worse. Keep looking. The 3 latches that secure the clamshell are driven by the same motor/rack&pinon/bowden cable assembly that move the clamshell. During the last bit of travel during closing, the left and right sliders engage the secondary slider. That slider moves an arm that secures the latches on the left or right side. The rear center latch is driven by an small bowden cable that is attached directly to the rack&pinon drive. It moves during the last bit of travel. The way the motor knows how many revolutions to turn to fully secure all of this is via a potentiometer attached to the motor drive shaft. This is one of the key settings in "convertible top calibration". Perhaps calibration is out of sync? Although there should be no reason for it to get "out of sync" unless something breaks.

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That makes a world of sense! Thank you so much! I will keep looking! Can I pls request that Workshop manual regarding the Pot resistance check and calibration for Clamshell? I think I should start there. Also wanted to ask, working on the pot, does it trigger a need to recalibrate the whole top?

I'll see if I can find the workshop manual. PM me your email address. As far as the potentiometer, I was able to remove it, note the position of the clamshell, and carefully mark the potentiometer's position (not turn it.). I reinstalled everything, and put the pot. back with the clamshell in the exact same position. Voila, no recalibration needed. Your mileage may vary.

Awesome. PM sent. I noticed my scanner is able to read calibration parameters on the top. Let me paste that. Does everything seem normal on the 'compartment lid'/clamshell pot and otherwise?

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Wanted to thank you for this little nugget of gold, it saved my bacon today. None of the you tubes I looked at mentioned this or how to get to the lower bolts easily (speaker grills). Have a great Sunday evening... C