Faulty Power Roof II

Inexperienced Joined: Jul 20, 2012 Posts: 21

I'll re-post this as I hijacked the post of mattperformance and I don't want it to be confusing when helpful people reply!

Can I get on this bandwagon too please! I agree with Matt, going to an auto-electrician to fix a faulty power roof is unlikely to bear fruit. It will cost you £80 for a code read before you even begin, then there will be much headscratching as they don't have the workshop manuals to work out exactly what codes mean what and which sensors and components are and are not working. I live about 30 mins south of Birmingham, so if there is anyone in the West Midlands area who is clued up on the foibles of these audi cabriolets then I would gladly pay to have it investigated and fixed. So is there anyone out there who might make two audi cabrio owners very happy??

So to my problem. I bought a 2000 2.6 Cabriolet with the power roof not working at all, the roof would not release and the roof button had no effect. At the time I thought it was cheap enough for me to get the hood working within a budget. This is what I have had done so far:

1) I had the wiring looms in the boot professionally repaired when it was in having a new rear window sewn in. This immediately got the 1st stages of power operation working, the hood would release, the windows drop and the hood began to fold back. The centre console roof switch was loose in its 'hinge' and someone had been messing with the bootlid lock and microswitch so....

2) Fitted replacement hood switch known to be in good working order.

3) Fitted replacement bootlid latch mechanism, striker plate and microswitch.

4) Replenished roof motor reservoir with green hydraulic fluid as had dropped below minimum.

HYDRAULIC FLUID REPLENISHMENT: At this stage I was convinced all would go swimmingly. It didn't, the hood would retract to the same stage and get no further. I noted that the fluid had dropped to below minimum again. Another faff filling it to just above MAX with a syringe.

The owner of my last cabrio, a 1997 2.8 with gorgeous electric heated Recaro seats (!), had cured the faulty roof on that car by fitting a new reservoir kit from Audi for about £30.

I proceeded to remove the roof pump on this '99 cabrio and scrutinised the reservoir and gasket for cracks and leaks - I found nothing awry. I put kitchen roll under the reservoir before refitting, and after several goes with the hood I am almost certain there are no leaks. However each time I've gone through a few hood lowering and raising procedures, which is half auto and half manual erection, the reservoir always drops to around minimum. I have checked around all the hydraulic pipes and I am as certain as I can be that there are no leaks - - where the "extra" fluid goes is anyone's guess. I understand the system is "self-bleeding" and that the level must be read when the hood is stowed away. BUT this is impossible as my bootlid remains locked (as it is designed to do) whilst the hood goes through its hood lowering technique so it always stops when the hood is full folded away at the point when the hood cover should then lower and latch shut. Accordingly I can never access the boot with the hood folded down!

WHERE MY POWER HOOD OPERATION FAILS "the point of no return": It releases fine, the cover raises up, the hood retracts smoothly and gracefully into the stowage compartment, then when the raised hood cover is expected to lower itself and latch shut it does not. It stays up and operating the switch just keeps making the latches raise up to await the lowering of the hood cover, which never happens. If I then try to raise the hood out of the stowage compartment it will not raise at all. I have to switch off the engine whereby the hood cover will drop, then the hood has to be raised manually.

If I lower the hood electrically to the point where the cover is raised and the hood is almost fully folded away into the stowage compartment I can abort and raise the hood back electrically on the switch and it all proceeds perfectly. Before the point of no return I can raise and lower the hood cover perfectly. It will latch shut as it should and I can hear it engage on latching which triggers the bootlid lock to unlock as it should, and unlatch and raise. Therefore I am convinced that there is nothing wrong with

a) any of the hydraulic rams
b) the level of fluid in the reservoir

I do have to have an assistant hold the hood cover a bit further back than it raises to naturally or the edge of the hood catches on it, but I believe this will be the two little gas struts have weakened over time which are not connected to the power roof system, rather than the central hydraulic hood cover strut which is part of the electro-hydraulic roof system.

So this is where I find myself. I know it's not the typical dodgy bootlid lock/latch mechanism, I know it is not the bootlid wiring looms, I am almost certain it is not a deficiency in the hydraulic fluid level. From being able to operate the hood and its cover to the extent I have I am fairly certain that the hood pump and valves/solenoids are all working as they should too.

I hate code reads and all that binary data and VAG COM twaddle, so for now I think the next culprit must be the hood control module. I also have a 1994 2.6 cabrio with a perfectly working power roof. Imagine my irritation to today discover it has a different part number for the roof ECU!!! It is 8G0 959 255 whereas my 1999 cabrio is 8G0 959 255 A... I have tried the '94 ECU in the '99 car but it won't allow the hood cover to release at all so is clearly not compatible. This is even more annoying had my mechanic got this '99 car MoT'd on time I would have been able to swap the hood ECU from my now sold '97 cabrio into it grrrrrrrrrrrrr. I will now source a replacement ECU and see if that sorts me out.

HOOD COVER SUPPLEMENTARY STRUTS: I also need two hood cover struts/shocks so the cover will raise to the extent it should - does anyone have any I could buy or know the part number, or an alternative supplier to my main stealer?

If any bored soul cares to read all of this and thinks he could shed any light on this issue please, please, let me know!

Posted: Thu Aug 02, 2012 9:20 pm

belugablack,

It was good to post it in a seperate post as it keeps them seperate. I Still think to get any where we will need the list of error codes and the measuring blocks from the point when it fails. Realise that might be difficult.

I think your right the hydraulic fluid is not the issue. You should be able to put the roof down fully manually and check the level accurately.

I would not change the rams until the error faults are checked.

By the way there are no gas struts in the system there are five hydraulic cylinders. One for the top cover and two either side. If the rams at the side are leaking you can usually find signs of this if you remove the back seat as it leaks from behind the side panels into this area. The seat foam can act like a sponge soaking it up. Leaks tend to be small from the cylinders large leaks might be a cracked or broken hose.

Anyway keep posting as you work your way through the issues.

Inexperienced Joined: Jul 20, 2012 Posts: 21

Dredging up this as I could do with having my roof working having had too many things to do to get it sorted last year, just had the codes read today and these are flagging up:

ELECTRIC ROOF CODES

01089 –Switch for tensioning strut stowed (f204) undefined switch position

01099 – Switch for luggage compartment lock not a plausible signal

01107 – Convertible top locked indicator light short with power (intermittent)

00258 – Solenoid valve open circuit intermittent

00271 See repair group 1 (intermittent)

This was an initial code read I guess with stored codes, how do I get the measuring blocks that someone mentions. Armed with the errors codes above what should I be doing next please? Please help as it is doing my head in having a nice looking cabrio that I cannot put the hood down at the touch of a button!

Inexperienced Joined: Jul 20, 2012 Posts: 21

1) The 01089 fault code is the first I want to try to eradicate, from what I can digest is it right that there are two microswitches which show the tensioning bow raised and stowed status and my F204 switch is not giving the signal as stowed as it should before the next stage in the sequence is allowed to proceed?

2) Could someone please tell me exactly how to locate this switch please - is it on the tensioning bow/strut itself? Do I access it from the boot by removing all the carpets (again!) or do I need to remove the rear right interior doorcard? Once located it it likely to be the switch itself or the loom to it that is faulty? I have had the bootlid looms replaced professionally incidentally.

3) Assuming I am smart enough to fix one of the offending gremlins, do I need to have the fault codes erased or reset by VAG com before I can expect the hood to work properly?

4) When my hood compartment cover raises automatically it does not raise up quite high enough for the hood to lower itself without catching on the cover, I have to manually hold the cover a bit higher so the hood clears it. Is this likely to be the hood cover compartment cylinder/strut (Part no. 8G0871605) that is weak or faulty or the two small gas dampers that are fitted to the hood cover hinges (Part no. 8G0825373C) that have gone weak? Has anyone had to replace these two small dampers in the hinges with any success - I've replaced loads of tailgate dampers on Golfs and Range Rovers, but at £40 each from Audi I am loathe to replace them if it's the central hydraulic strut itself that it failing to raise the cover as high as it should.

Posted: Thu Jun 06, 2013 10:15 pm

204 is inside the cylinder. You dont need the fault codes erased for the system to work. The fault just needs to be fixed for the logic to work through the lowering process.

Inexperienced Joined: Jul 20, 2012 Posts: 21

Thanks for that CCV6, I've managed to fix point 4) on my last post. I bought a used pair of the little gas struts that fit to the hinges of the hood cover (part no. 8G0825373C) for £20, new they work out at £80! Off the car I could not compress the new struts even a milimetre whereas the ones I removed compressed fully with no resistance at all so they had failed totally. It was a real fiddle to get the circlips popped in to retain the strut eyelets on the hinges' top shafts as access is tight even with my spindle fingers but I managed in the end with some needlenose pliers and a torch. After a little adjustment to the central power hood strut fixing on the hood cover I was chuffed to see the hood cover raise itself sufficiently for the first time so the hood clears it when stowing itself.

Motivated by this result I then painstakingly replaced the wires running in the loom from the OSR roof hydraulic ram (or tensioning bow) that sits behind the rear headlining if you're sat in the rear seat driver's side as far as when they leave the hood and go down into the body as I see someone else on here successfully cured their faulty power roof as the wires had kinked and broken. With the webbing off the loom I could not see any breaks in the wires but as there were a few kinks I thought I should replace the wires anyway in the event they're stretching and breaking down inside the insulation. Naturally I could not be so lucky to have two ace results on one day and find myself with a fully functioning power hood could I!? No, still the same situation, roof folds itself down into the box and then the process stops.

NEXT STEPS:

I am thinking it could be the F204 switch on the tension bow ram itself at fault so am searching for one of those - - anyone got one please?

Also I have found from German sites that the tension bow struts are different for later cars, mine is 1999 V-reg, as the hood pump itself changed at some point between 1992-2000 from having 8 hydraulic valves/pistons to 6, or is it the other way round as I've re-fitted all the boot carpets back since I decided my pump was fine - so cannot check what pump I have.

Finally I read on this post on this site a chap who had the same F204 error code crop up on his cabrio and he reckons the hood ECU was it fault and a replacement cured it.:

http://www.audifans.net/ftopic-32299-previous.html

The first thing I did last year was to source a replacement hood ECU and this did not solve anything - - but now I am thinking perhaps this fault in the ECU is common and the replacement ECU is just as faulty, which would be typical for me. As my 1994 cabrio uses a different hood ECU (doh!!) is there any kind soul in the Midlands with a working power hood and later model car that I could borrow the hood ECU from for 5 minutes to rule out this potential source of trouble?!

Posted: Mon Jun 10, 2013 8:51 pm

Measuring Block 2 in group 1 might give a clue

Stage 8 Display Group 1 - 01010100 - The rear tensioning bow is lowered slightly in to stow area.
Stage 9 Display Group 1 - 01011010 - Convertible top is stowed in compartment
Stage 10 Display Group 1 - 01001010 - The convertible top compartment cover is lowered slightly

If its stopping at stage 8 then it might be F177 - Top stowed switch. If it stopped at stage 9 then F201 is a possibility. These are the only switches that change during this stage.

Inexperienced Joined: Jul 20, 2012 Posts: 21

So four years on from starting this post I still have my 2.6 Cabriolet and I still have not fixed the faulty roof! Two weeks ago I decided to go at it in earnest and had my GTI specialist with VAG.com interrogate it. The fault codes were not convincing and he agreed that this time, (the symptoms change from year to year when I gingerly try the soft top, two years ago it did it's first ever complete cycle down and stowed perfectly when I first tried it that Spring, then promptly stopped working again!) it looked like a hydraulic fluid issue. Worse luck it appeared that the lower right ram had been weeping, only slightly, no pools of fluid, so I spent 5 hours solid replacing this ram. I was not convinced but it made sense with the rear interior panels removed.

Fitting the replacement ram was very tricky at the top fitting, the access is very tight and the locating clips are a devil to get on and not drop down inside the car. Keeping an eye on the level in the reservoir after a few cycles with some manual intervention I had only achieved the impossible and got the blasted power hood working perfectly, up and down, absolutely perfectly. The biggest triumph I have had on a car and to drive the car in over 6 years without the red hood fault light flashing at me was a revelation too. I used the hood for 3 days and it did not fluff in the slightest. Yippeee I shall get it booked in for a full professional respray as after these years I am quite "into" this car.

Then the hood lowered itself and could not quite manage to fold the hood in the stowage compartment tight enough to latch down the right lock of the stowage cover, I heard the left stowage latch lock as it should but the right would not. Lo and behold the fault light reared its ugly head again and the roof would not budge either down or back up. I thought that seeing it had been "Fixed" it was just a teething trouble - I even disconnected the battery and the hood ECU overnight. No joy. Spent a whole day on it. Got nowhere.

I hate it when people use and abuse these forums and never follow up whether they had a success or further failure so I was even looking forward to being able to resurrect this thread and say "Hi guys, do not despair, after 6 years I have fixed my hood and these are my tips!"....

What happens now is roof fault light flashes as soon as the car is started, the windows drop when the top latch is freed and the roof raised by hand, when I pull the power hood button I just get a click, nothing else, just a click whenever the button is activated. The rear roof section makes no attempt to raise up and fold in readiness to release the stowage compartment. I have now pinpointed this click to being from the solenoids on the pump unit.

This fault is something new as if you read my original post you will see I used to get much further into the lowering process, the hood would lower and stow away but the stowage compartment cover would refuse to lower.

Vag.com this time gave confusing results. As it failed at the point of the right hand stowage cover latch failing to lock down I was sure one of the three microswitches in that assembly had failed. The guy on the laptop said it was suggesting the stowage compartment raising and lowering hydraulic ram as being the culprit.

In the last two evenings I have changed the right hand stowage cover latching unit, the central hydraulic ram for the stowage cover, the entire hydraulic motor and pump unit (so all new solenoids and relay too) in the boot, the LH upper hydraulic ram and RH upper hydraulic ram - the one with the microswitches (tension bow) and the roof ECU. Guess what - still exactly the same fault. The rear of the hood refuses to budge and there is a click at one of the solenoids on the pump/motor unit but no whirring into life.

I have checked that the boot latch switch works - manually operating it turns off the boot courtesy light as it should, but I do not think this would affect the lowering process at this early stage as I have checked on my other Cabriolet and the bootlid does not lock until after the rear of the hood has raised fully at which point one hears the bootlid lock and the stowage compartment latches unlock.

So my roof worked absolutely perfectly for 3 days in July 2017 after changing the RH lower ram then stopped and now faults at an earlier stage than ever. It is driving me CRAZY. What type of fooooooooool persists driving a 2.6 litre petrol car everyday when the sodding convertible roof gives him such aggro?????

It has been such a protracted mission that I am wondering if after all this time that the wiring looms from the bootlid that I had professionally replaced when I first bought the car could now have gone faulty...

Please someone offer me some advice.

Inexperienced Joined: Jul 20, 2012 Posts: 21

I can happily report that I fixed my roof myself, again, only this time I am crossing everything that it stays fixed!

So if you have read my previous post after 6 years I had briefly got my hood working for 3 days only for it to fail again. I would unlatch the central lock, push the roof up, the windows would lower, but operating the roof switch saw no movement from the roof just a click from a solenoid in the boot.

Vag.com said it was the stowage compartment hydraulic ram, it was not. After changing more rams at the weekend, yesterday I fitted a second replacement lower RH ram, the one with the switches on it that is a real, real fiddle to fit. I figured as this is what had caused me to have a fully operational roof two weeks ago, maybe the replacement had gone bad. Typically it took me even longer to fit this one as I had just been lucky getting the fixing dowels and clips on relatively smoothly a fortnight ago. Did this fix my roof? No, exactly the same fault, a clicking solenoid.

I then had a really good look in the fusebox, I checked the two fuses that the label on the lid said were for the manual or hydraulic roof, all were fine. I then decided to take out every single fuse in turn, (I wanted the ampage rating numbers all facing the same way!) and by sheer chance I found a broken 25A fuse in the yellow holder. I have been too unlucky with this car to have been hopeful that this would be my fix, and from the fuse layout diagram it gave me no clue as to what number fuse this was or what it did. Put a new 25A fuse in and tried my roof - RESULT, immediately the rear section whirred into life and raised and the hood lowered itself without a glitch. For my own sanity I removed the 25A fuse and tried the roof, just that blasted solenoid clicking again so I am 100% sure that the blown fuse caused my roof to refuse to open.

The salient point is that vag.com gave no indication of this whatsoever, my guy was on this for an hour last week and each time after clearing the fault and trying to get the roof to open, and with lowering it manually through the stages it came back with three error messages, both suggesting problems with the stowage cover ram and latching locks - - nothing about a duff fuse.

As I have said the fusebox cover label is next to useless. The 20 vertical fuses can be easily pinpointed as have a number next to their location, fuse 21 onwards is another story. The 25A fuse was the first on the left of the horizontal fuses on the front-most row, before the double red fuse with "Moteur" inscribed on it. By my logic the 25A would be fuse 21 but on my cover label that pertains to a diesel engine and NOT a power roof.

So it would be a very good idea to keep an eye on the yellow fuse holder in your fuse box as if your stowage cover cannot quite push the folded hood down far enough to enable the cover's latches to lock it can blow this fuse and then your power roof is totally kaputt.

To hopefully end this saga, I know people have praised being able to plug their cars into a laptop or scan tool and interpret measuring blocks to pinpoint the cause of their particular roof malady, in my experience vag.com has taken me up the garden path and around the houses and then some. Experts have failed on my roof, both times it has been fixed by me, a non-mechanic or auto-electrician and with no plug in buddy to hand.

My original code read years ago (£35 trade price down the drain) told me the tensioning bow F204 was at fault and eventually I found that this meant the upper RH bow. Over the years I have had four different tension bow rams fitted, three different hood ECUs and this never fixed my problem. My problem all along was a leaking lower RH ram, behind the rear interior panel.

The leak was on the lower RH ram was not drastic either, no pooling of fluid but in hindsight the reservoir was going down slightly over time so I should have cottoned on that if I could not see it leaking on to the hood cover from the top rams then it must be down below.

Accordingly my advice when embarking on a project car with a fault power roof would be:

1) Get the bootlid wiring looms replaced
2) Remove your boot carpeting so you can check that the pump's fluid level is correct in the reservoir.
3) Check the 25A fuse in the yellow holder, front left in the fuse box is good.
4) Get a code read and see what error messages are being flagged up but take it with a BIG pinch of salt. If it comes up with something easily determinable and fixable, lucky you!
5) If your code read result leaves you remotely perplexed STOP! Do not go down the route of swapping ECUs, rams with microswitches or latching units.
6) Instead keep an eagle eye on the fluid level in your pump's reservoir, if you roof is totally kaputt, get a mate to help you lower and raise your hood a few cycles manually. Top up your fluid if necessary using the syringe method, does it seem to be going down?
7) My roof fault, I believe, was entirely down to a hydraulic issue but vag.com was telling me it was seeing electrical errors. So as you do not need to be an expert to watch a fluid level, get yourself to a point where you are sure you have no loss of fluid problems before tackling the expensive electrical side.

If your car's roof has been faulty for some time be wary if the previous owner says "Oh we have justed used it manually" as I believe manually opening and closing a hydraulic roof can cause if not exacerbate the leaking of the hydraulic rams.

Others may pounce on this but I think my leaking lower RH ram - this is the one with microswitches either end of its shaft remember - was not able to extend or retract fully due the presence of a leaking seal, but instead of the switches on this ram sending clear information to be drawn off as error codes pinpointing this ram as faulty, it merely transmitted, and erroneously, a message down the line which came back as the F204 tension bow sited above it at fault when code read, a total red herring which has cost me dearly.

It is really worth your while to remove the rear seats and remove the rear interior side panels and not just check for obvious leaks of the lower rams puddling beneath on the car's floor pan, but look and feel at the top of these rams where they are hidden in the bodywork for less profuse leaks. Remove the rear speakers which give you better access and satisfy yourself that there is no fluid seepage from the lower rams.

Having changing so many rams I have noted that you need a very high quality spanner to tighten up (and free them off in the first place!) the hydraulic hose connection nuts on the rams, 14mm off the top of my head. My spanners were useless, I borrowed a really good Draper professional spanner off my mechanic. Furthermore with the replacement ram installed on your roof frame you cannot adequately tighten up 14mm hose connectors. Over time I have replaced rams that I thought were leaking but it was actually fluid leaking from the hose connections by the nuts. To this end when I have fitted the ram to the roof frame I grip the ram's shaft with mole grips (be prudent here, as tight as you dare without going over the top) with one hand so I can tighten the 14mm nut with my decent spanner as much as possible with the other hand to get the connectors fitted as tightly as I dare. This is an essential step I feel to avoid annoying and unnecessary leaks at the connectors.

An interesting end point is that my latest 2.8 Convertible is one of the last, a 2000 model and there is an Audi main dealer invoice at the 30,000 mile service when the car is less than 3 years old saying "Customer notes fluid leaking from roof system onto hood compartment cover on both sides - thoroughly investigate but no leaks found". End of story, typical main dealer fob off there or what! You can imagine the conversation: "There are no leaks sir, everything is fine, I know you paid £32,000 for your Audi Convertible from us a couple of years ago but there is nothing to worry about I can assure you....". So despite all the over-engineering of these Audi's, it appears that even 7 years into the production run your could still get leaking rams before the car was 3 years old.

Site Moderator Joined: Jan 31, 2003 Posts: 9144

I admire your persistence.

Pretty sure I may have some wiring diagrams for the electric roof somewhere. Will see if I can get them online.

Manual roof diagrams are already online on my website

Posted: Thu Jul 27, 2017 10:11 am

as Mike said well done & thanks for reporting your outcome etc Very Happy