Sagging Roof bellows in hot weather - experiences

[WelshGas]

My 73 plate T6.1 does. Happened last night and does quite often. I have noticed times when it doesn’t, I put that down to me turning the vehicle on and off rather than just turning up and turning the van off then taking the keys out. I’m always forgetting the roof needs the keys in and ignition on to raise it. Not sure if that’s why it hasn’t auto corrected some times.

Normally the retensioning occurs 10 hrs after last Ignition Off.

 

[sidepod]

I suppose it depends on the cause of the sag. If due to fluid loss or a faulty valve then the sag would be progressive over time.
But if due to pressure relief due to high daytime temperatures and cooler nights then one would expect the pressure in the system to increase when the temperature rises , reducing the sag, and sagging again when the temperature drops. Unless the high temperature is greater on the 2nd day , producing a higher pressure and thus activating the pressure bleed valve, the degree of sag should be unchanged in the evening.

So up and down like a yo-yo, day to night. It doesn’t. Once the sag sets in, it just keeps going.

 

[sidepod]

My 73 plate T6.1 does. Happened last night and does quite often. I have noticed times when it doesn’t, I put that down to me turning the vehicle on and off rather than just turning up and turning the van off then taking the keys out. I’m always forgetting the roof needs the keys in and ignition on to raise it. Not sure if that’s why it hasn’t auto corrected some times.

Did you happen to note how far it had sagged when the auto-correct operated?
For example, had the upstairs lights stopped working due to sag?

I’m trying to ascertain what the software uses to determine roof movement. Either failed roof lighting or ram position sensors. It may well be the same thing, the sensors deactivating the lighting?

 

[DianeM]

24 plate Ocean, We are currently travelling and the roof sags on the passenger side almost everywhere day, doesn’t have to be that warm. Hubby is a hydraulic engineer and says this definitely shouldn’t happen either the seals in the ram or the check valve aren’t working, diggers can sit for weeks holding great weight and don’t creep down. We are still travelling but will be. He getting very annoyed

 

[sidepod]

24 plate Ocean, We are currently travelling and the roof sags on the passenger side almost everywhere day, doesn’t have to be that warm. Hubby is a hydraulic engineer and says this definitely shouldn’t happen either the seals in the ram or the check valve aren’t working, diggers can sit for weeks holding great weight and don’t creep down. We are still travelling but will be. He getting very annoyed

I’m glad finally someone in the know pointed that out.

 

[DianeM]

I’m glad finally someone in the know pointed that out.

I should also say we have previously owned a 19 plat T6 and didn’t have this issue. I’m getting the blame for pushing for the new van, he had a list of dislikes compared to the T6, something dodgy with the sliding door lock too we were locked in the van yesterday had to put the window down and open it from the outside. I won’t list all his complaints

 

[Betsycalifornia]

Did you happen to note how far it had sagged when the auto-correct operated?
For example, had the upstairs lights stopped working due to sag?

I’m trying to ascertain what the software uses to determine roof movement. Either failed roof lighting or ram position sensors. It may well be the same thing, the sensors deactivating the lighting?

Lights out, they went out as we went to bed and the autocorrect kicked in during the night.

 

[Oceandrive2023]

Lights out, they went out as we went to bed and the autocorrect kicked in during the night.

Interesting ! Can't understand why I was told that T6.1 don't have auto correct .

 

[sidepod]

You could try to provoke an auto-correct.

Ignition on, roof up, upstairs lights on.
Close the roof until the lights go off.
Ignition off/key out
Wait 10hours.

 

[vbk1975]

You could try to provoke an auto-correct.

Ignition on, roof up, upstairs lights on.
Close the roof until the lights go off.
Ignition off/key out
Wait 10hours.

I have been trying to work out the auto-correct for the T6, i can't state for sure, but I think the system is looking for one of the fully open sensors to change from open to not-open after the system has driven the roof to open (and seen the electrical load on the pump that indicates it has been fully pressurised.) , this check happens after X hours from ign off and I assume just drives the pump until it sees the sensor change and pump electrical load spike. But having had a look at the roof symbol vs the roof drop, it is a reasonable drop for the sensor to change from open.

As per your suggestion above, so i think if you command the roof closed even a little bit, then the system won't try and auto-correct, but i might be wrong.

 

[WelshGas]

You could try to provoke an auto-correct.

Ignition on, roof up, upstairs lights on.
Close the roof until the lights go off.
Ignition off/key out
Wait 10hours.

Why would they change the system that triggers the auto-correction for the T6.1.
The T5/5.1 doesn’t have roof lights and auto-corrected.

 

[Hawthorn37]

We also have a sagging roof, that happens when the roof has been up for around 18 hours. We need to manually lower the roof a bit, and then raise it. I was under the impression (from the handbook) that auto correction would tension the roof. It doesn’t happen for us.

 

[CaliforniaCylus]

The auto correct works seemlessly when you leave the vehicle alone. Put the roof up, take the keys out and at 10 hours it will re-inflate if necessary. And then at every 5 hours. Once it doesn't need to correct it never checks again.

Whilst not documented, the timer appears to be disabled by turning the ignition on. I think there are other functions that also cause this reset.

I think the TPI is documented in this thread in that the roof has to fall 20cms in 72 hours. Of course leave the vehicle alone and it auto corrects so you never meet the VW criteria. Unless it's massively broken.

Also I think autocorrect only kicks in at the point the lights switch off. So if they switch off at 10 hours and 1 minute, no re- inflation.

 

[jaydisc]

When my roof was sagging heavily on one side, the auto-correct never occurred. The sagging would happen consistently within 30 minutes, and the lights would cease functioning.

After VW "bled" the roof (performed some process, waited 72 hours to measure again, and repeated it 3 times), my sagging is now rare, even, and is usually auto-corrected. I'd say 1 out of 10 times, it isn't corrected, and I do the old lower-it-a-tiny-bit-and-raise-it-back-up-again, and all is fine. I haven't done any serious documenting as to whether I've possibly turned on the ignition the times it hasn't happened (sometimes I shift the van to get better solar). I'll try to to keep an eye on that moving forward.

My build date is 09/2023.

 

[sidepod]

Why would they change the system that triggers the auto-correction for the T6.1.
The T5/5.1 doesn’t have roof lights and auto-corrected.

You’ve misunderstood. The lights are merely an indicator of roof being in a position to require an auto-correct.

 

[WelshGas]

I’m trying to ascertain what the software uses to determine roof movement. Either failed roof lighting or ram position sensors. It may well be the same thing, the sensors deactivating the lighting?

In your Post 53 you mentioned the possibility of Failed roof lighting as there trigger for Auto Correction.
I was just pointing out that the T5s don't have the roof lighting so unless something has changed it must be the Ram sensors unless there is some form of Pressor sensor in the pump circuits within the pump.
The Auto Correct also works without the Ignition ON which is required in normal use of the Hydraulic Roof.

 

[vbk1975]

In your Post 53 you mentioned the possibility of Failed roof lighting as there trigger for Auto Correction.
I was just pointing out that the T5s don't have the roof lighting so unless something has changed it must be the Ram sensors unless there is some form of Pressor sensor in the pump circuits within the pump.
The Auto Correct also works without the Ignition ON which is required in normal use of the Hydraulic Roof.

For clarity, the electrical system and the roof system control are completely different between a T5/T6 & T6.1.

The basic pump / sensors are common between the two.

On T5/T6 there is a dedicated roof ECU (That is a modified Saab Controller) that does all the roof functions, the Control Panel just sends up/down requests and shows the warnings. So not really integrated at all and the rest of the Camper functions are done by the Control Panel, which itself is largely stand alone and only has very basic connections into the base van.

On T6.1, they moved all the Camper functions inc. the roof control logic into one ECU, so the Roof Sensors and Roof Pump outputs are all in the same box that controls the lights etc. So on T6.1 they have used the Roof Sensors as a trigger for switching off the roof interior lights if the roof is lowered etc. But there is lots of evidence that suggests that when they tried to mimic the T5/T6 roof control stuff, they missed some of the behind the scenes features (Auto-Correct wasn't the same on very early T6.1 vans until a software update). I don't have a T6.1, but reading all the various T6.1 roof threads over the last few years, it is clear the T6.1 roof control strategy isn't identical to T6, probably just lack of full understanding of what the old controlled did, but also the T6.1 ECU can be updated by the Dealer, nothing in the T5/T6 camping system can be.

Also with the number of sagging roofs on the T6.1, the interior lights being switched off automatically when the roof dropped was an indication of the sagging issue. But on T6s the roof lights have no idea of the roof state and hence don't change with a dropped roof.

There is no electrical pressure sensor in system, so the only way of detecting roof drop is the roof sensors.

 

[sidepod]

Yes I think subsequent posts established it’s the roof sensors that control the system but, thank you WG for being so forensic. What would we do without you?

 

[WelshGas]

Yes I think subsequent posts established it’s the roof sensors that control the system but, thank you WG for being so forensic. What would we do without you?

It would seem one possibility is software. It would be interesting to compare Control Panel software versions on vehicles that do Autocorrect with those that don't.

 

[myvanrodney]

We also have a sagging roof, that happens when the roof has been up for around 18 hours. We need to manually lower the roof a bit, and then raise it. I was under the impression (from the handbook) that auto correction would tension the roof. It doesn’t happen for us.

we have this too, sometimes! when it does happen, i just lower slightly and raise again. The problem i have is we don't always know if the auto correct has operated when we have been away from the van or in the night when we are asleep.... so i've just filed it in the 'annoying but not life threatening' folder

 

[WelshGas]

we have this too, sometimes! when it does happen, i just lower slightly and raise again. The problem i have is we don't always know if the auto correct has operated when we have been away from the van or in the night when we are asleep.... so i've just filed it in the 'annoying but not life threatening' folder

I think if the Auto correct operated at night you would know about. It’s very loud in the stillness of the night.

 

[myvanrodney]

I think if the Auto correct operated at night you would know about. It’s very loud in the stillness of the night.

agree... altho me AND my wife are award winning snorers ! Who knows what noises fail to compete with our trumpeting

 

[sidepod]

I tried to initiate an auto-correct yesterday by lowering the roof until the sensors were out of range then leaving it , IoKo.
24 hours later it’s still low.

I’ll have another rummage around in VCDS today to see if I can find anything.

 

[jaydisc]

I would never presume that to work. If I was programming the system, it would be like:

1. Car is turned off
2. Is roof up? Yes - start timer. No, do nothing.

 

[jaydisc]

It's still a fine thing to test. But I would not assume a lack of adjustment to be conclusive in any way.