Cabrio Hood Problems

[kevinuk]

My 1994 993 cabrio started to light the roof open warning light mid last year on odd occasions when the roof was closed. A quick half open and close again always sorted the problem. Took the car out last week, same problem but this time the roof opened but would not close. From part open it will continue to go down but not up...any ideas.?

I have now established that the hood control box is located behind the glove box which needs to be removed to access it.

After some fiddling and checking I am guessing that it is either one of the micro switches or the control box that is faulty

 

[p27549]

I would definately look at the micro switch on the right hand side of the car. Mine did exactly the same with the PA1000 auto closure. i would close the roof remotely and then on return the roof unlock light woul dbe on. Adjusted the microswitch and it has gone away. It is very easy to do.

 

[kevinuk]

Thanks, tried that with no joy. Have now changed the micro switches for new and still doesn't work so I am guessing it's the control box.
I have managed to locate it behind the glove box which has to be removed for access.

 

[D Ward]

As you said its quite likely your hood control box that is the problem, £700+ from you friendly porsche dealer, thank you sir lol.

All you need to do is remove the hood control box, open it up, then take a close look at the silver plug pins where they are soldered through the circuit board, you will most probably find that the solder around one or more of the pins has cracked, if so, you just need to apply heat with a soldering iron to the back of the pin so the solder flows back into the crack.

If you don't fancy tackling it yourself, then if you got a tv repair shop or similar near you, they would most probably solder it for you.

When you put the control unit back in, its worth trying to pull a bit of slack on the cable & the four large plugs to the control box, as its one of the reasons the unit fails, as it puts too much strain on the control box pins ( when you buy a new unit from porsche, it comes with a new loom extension piece, to try and prevent strain on the control box )

out of intrest, the reason for the hood control unit failing, apart from the strain placed on it by the tightness of the cables, is due in part to the reduction of lead content in solder since the nineties, which makes soldered joints less flexible and more prone to failing ( google "tin whiskers" for a more detailed explanation than mine, as to why, electrical items, control units, ecu's etc fail quite regularly )

Anyway hope that helps get your hood working again, Thanks

 

[kevinuk]

Thanks..I think you are spot on. I have found a place in Kent called BBA www.BBA-reman.com that will test and repair all Porsche control boxes. They charge 35 Gbp for a test and 150 Gbp to repair. Unit then comes with a warranty so a good option versus the astronomical price of a new part from Porsche. I have tried the re solder route but can only get it to work intermittently so I am going to give BBA a try.

update..decided to have another bash at the soldering of the main pins...success it works ! lets hope the fix lasts

Interesting issue on putting everything back together. Even though there was enough power to open and close the hood, light the interior light etc when I tried to start the car...nothing ! not a glimmer. The tip gear position indiactors on the dash were flashing 2nd and 3rd. as the solonoid was not clicking I assumed it was the immobiliser.

I put the battery on charge and tried again after two hous..bingo it started no problem. strange !

 

[mmylonas]

Have you had the Porsche recall work done on the hood? Porsche Reading did it for me a while ago (for free). Don't know if it's of any relevance to your issue but worth checking anyway.

Michael

 

[D Ward]

Glad that fixed it for you, re soldered mine about 12 years ago and still working fine.
I had a similar thing with the battery seemingly perfect for raising and lowering hood etc, but it would not start the car, turned out to be the earth strap from battery terminal to body, it looked brand new, but had very high resistance. Worth checking, caused lots of other intermittent electrical problems till I found the earth strap was faulty.

Just my opinion, but if your car has not had hood motors changed under warranty, i personally would not bother, the replacement motors are not as well made and their are lots of reports of the new motors failing within 18 months. Besides the recall is open ended so im going to save it till or if my original motors fail. Yes i am well aware of the reason for the recall, slim risk of gear cog failing and releasing hood, but as the chances of both locking motors failing at same are so small im not really that concerned

 

[kevinuk]

Thanks for the tip on the earth strap...probably worth changing as it is relatively cheap item

 

[kevinuk]

Yes recall work was done..thanks
Update..hood worked for a week and then same problem. I can now strip out the glove box in under 5 mins!! So my soldering clearly was not up to scratch. Bought a new soldering iron and have had another bash..working again..lets see how long.
Went on eBay last night and bingo a brand new control box for sale in the USA for 230 quid (versus about 500 from Porsche) so I decided to go for it just in case. If my repair holds you may see it for sale on eBay uk later this year

 

[kevinuk]

Update...the repair seems to be holding up. Drove over 100 miles at the weekend and all working fine. Still have the problem of the hood warning light coming on but only after the car has been started for the second time in a day, never on initial start up. This happens every time even if the roof is not opened. A quick open close and the warning light goes out!!

 

[Dekker]

I would suspect you have had 2 faults and that now you've sorted out the dry joint, go and check the microswitch to see whether it needs adjusting.

David.

 

[kevinuk]

I have changed the micro switches tdc and hood open and I guess that the tdc micro switch is the one that indicates the hood is closed (or open). These are set up and work fine and from a first start up in a day there are no warning lights. It is always the second start up that brings the warning lamp on. I have even checked the micro switch contacts with the warning lamp on and the tdc is closed ( with hood shut). Open and close the hood and the warning goes away!

 

[Dekker]

OK I hadn't realised that you'd been so thorough on eliminating the micro switches from the equation.

I've paid attention to your posting because I have a small problem in the same area, only my roof open light is only on when the keys are out of the ignition. As soon as the key is turned on the light goes off, this problem only became apparent when I upgraded the instrument lights from tungsten to LED. So the current flow is too small for the tungsten bulb to show lit.

 

[kevinuk]

Frustrating isn't it ! I wonder if it is another fault in the control box?

 

[Dekker]

It certainly looks that way. I have a few other issues that are higher on the list of must do's, so I'll live with this for a while longer.

Cheers, David

 

[kevinuk]

Well my soldered repair is holding up well and hood is wrong a treat. The new control box I bought from the USA arrived Saturday with 58 pounds to pay for duty and Vat..ouch. Had not expected that. The guy shipped it with the eBay receipt showing my purchase price...top tip if he had declared it as a used part with a nominal value ..say 20 quid the duty and vat would have been nothing. Still I have the new box in standby now and it was half the price of OPC