DJB

My 86 Cab roof closes to the winscreen, where normally the two cams activate and fix the roof closed onto the top of the screen frame.

The LH cam has decided to no longer operate. Before I pull it apart - a couple of questions as it is not covered in Bentley.

Is each cam controlled by an indivual motor, or activated by the same motor. No fuses are listed for the cab roof in the manual - can anyone suggest what location the fuse may be?

Is this a common problem with a common solution?

Thanks

DJB

OK I have found the black electronic relay control box - under the false floor on the passenger side - but this does not seem to be fused.

Does anyone know which connector goes where - there are 4 within the integrated box.

Does anyone have an electrical diagram for the 4 relay box?

Thanks

Rob McConnell

Hi

I have a 964 not sure if its the same but there is a relay in the fuse box.

rob

expathk

Hi,

I don't know whether this will help but when I first bought my 87 Cab, I would sometimes stop the closing or opening operation mid way and then find it took several attempts before it would start locking up again. I would turn the power at the key off and on several times hoping this might somehow clear the problem. I even drove for two days without it properly locked and the red indicator light on saying it was not locked properly. I rang the previous owner and asked if he had ever had the same problem and this was a negative,, supported by the all the service documentation. Having done this I tried opening the roof all the way one more time and then closing it. Sure enough it locked up on closing. I learnt not to stop in mid procedure and have never had a problem since.

Initially I went the same track as you looking for power or motor problems but obviously this was a waste of time.

Just hoping that maybe this will be the same problem for you saving you more hassles.

Good luck.

Mark

alex'87cab

Hi DJB,
I had the very same problem on my '87 cab, and the helpful people on the list gave direction on how to fix it. First open your roof all the way, this will expose the cover over the cams that rotate to lock the roof in place over the windshield. Remove the cover by taking out the screws that hold it in place--it should pop out easily. You will see the motors and a black plastic switch with a spring-loaded dimple that activates the motor when it hits the windshield frame during the top closing, it is this switch that is most likely defective (it was on my car). You can buy a new switch from the dealer (In Canada ~$100, or try a salvage place). It is easy to replace the switch, its held in place by small screws. Replace the switch and your top should work fine. But before you try closing the top make sure the cam is not in the closed position--if it is use a screw driver to manually reset the position to open (with the power off) by turning the motor (tiring).

Good luck,

Alex J.
'87 Carrera Cabriolet

DJB

OK Fixed the problem and learnt a lot about Cab roofs. Big thanks to Alex 87 Cab your advice was spot on.

The problem was the activation switch which operates the cam motor, the switch contacts were corroded and out of alignment.

To get to the switch remove the cover of the motors with the roof in the down position. Two screws and a few pop type fasteners.

The switch is removed by removing the two screws. I cleaned and then adjusted switch to its maximum position.

The roof is not fused at all and there is a relay box located under the false floor on the passengers side.


Hope this helps someone in the future.

Cinge

I am experiencing the very same problem with my cams, except that the trouble comes when trying to open the top. My driver's side cam will sometimes freeze and not want to open. I am going to roll up my sleeves this weekend based on your discoveries and see if I can't fix this problem. (This site is so useful; thanks for posting).

Spring is here! It's topless time!


1988 911 Carerra Cabriolet (Signature Series)

realtime

Hi,
This thread makes my thankful I have a manual top!
<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

Christian S.

[quote]Originally posted by expathk:
<strong>I learnt not to stop in mid procedure and have never had a problem since.
</strong><hr></blockquote>

Very similar experience Mark - I came to the conclusion that the system must have a safety feature that stops the closure action if it senses any impediment. After trials and more trials I've found on my car (87 Cab) gently lifting the hood back at the same time as operating the switch in the same direction (opening) will re-engage the mechanism.

Very frustrating when it happens with no reference in the handbook or manuals to explain that nothing is necesarily broken. I've also had a microswitch failure which stopped one of the cams working - easy to diagnose with a multimeter once the headlining strip covering the cams and switches is removed.

It's also well worth making sure that when the roof is retracted it is adjusted to fold to the correct extent - too much and there will be strain on the frame and gear, too little and it will be loose - the locating grommets may be worn and are worth replacing and adjusting if that is the case to allow the top to be secure when folded.

I'm probably being over-sensitive, but I also use a hand against the roof headliner to "cushion" the initial impact of roof meeting window frame when closing..... it's just all a bit harsh for my mechanical sensibilities.....

Christian Stewart
'87 Cab

87slant-nose-cabriolet

THANK GOD I HAVE A MANUAL ROOF!
KEITH

Cinge

[quote]Originally posted by Christian Stewart:
<strong>
I've also had a microswitch failure which stopped one of the cams working - easy to diagnose with a multimeter once the headlining strip covering the cams and switches is removed.
</strong><hr></blockquote>

Could you elaborate on a multimeter? I've had this very same problem with one frozen cam in the closed position(only just twice though in the six weeks of being a proud owner of an 88 911 cabrio). Last weekend I took off the coverplate and couldn't visibly see anything wrong -- the 'dimple' switches and the cam motors are very clean. So mechanically it looks good; I suspect this may be electrical?

Thanks so much for your posts and any assistance you can give.

Regards,
"cinge"

Christian S.

Cinge, a multimeter is simply an electrical testing device - "multi" because it can perform various different tests, usually voltage, current, capacitance, resistance, continuity, frequency etc.

The digital variety is probably the easiest to use and recommended in the Bentley manuals that you may have heard of for various fault finding uses. Try <a href="http://www.multimeterwarehouse.com/digital.htm" target="_blank">http://www.multimeterwarehouse.com/digital.htm</a> for examples.

Don't be put off by the "electrical" complexity and capability of these devices, they are very simple to use and do not require much electrical knowledge or understanding (I'm firmly in the postage stamp department).

To use a multimeter to diagnose whether the two microswitches that turn the top locking cams off are working correctly, you simply need to turn the device's dial to it's resistance measurement and test the continuity of the switch.

A good meter will have an audible alarm (beep) to tell you when continuity is achieved - in other words a complete circuit.

First you need to open the top - a pain if either of the cams are not working as you need to insert a screwdriver into the manual locking slots. Doing this carefully, you should be able to "feel" the slot of the cam screw and once the headliner is removed a view of the condition of the screws will tell you how often previous owners have resorted to manual operation.

Once the top is open, remove the headlining cover that hides the cams and switches. You should then be able to fish out the microswitch connector plugs and unplug them. Simply place the positive and negative multimeter probes into the microswitch plug connectors and operate the switch with your finger by pressing it in and out and see if a circuit is created and broken by it's operation.

The microswitches are left and right items, so if you are ordering a replacement make sure you order the correct one. There is also a certain amount of adjustment in their positioning, so care should be taken in making sure that they "meet" the cam holders squarely.

I've also had my cams doing very strange dances occasionaly when nowhere near the windshield - but fingers crossed a proper full open and close of the top seems to reset the system and everything reverts back to normality.

Hope that helps

Christian S.

Cinge, another thought if the continuity of the switches seem to be ok - check that the microswitch dimples that meet the cam holders are properly "sprung". The microswitches have small springs inside them that make the dimples protrude and pop out when no longer in contact with the windshield. The dimples should spring out cleanly and without binding.

It's a very remote possibilty but if the spring is broken or not seated correctly it might lead to intermittent failure of the cam on opening.