Thread: SLS Issue

there are a number of sls threads on the site (not an uncommon issue). the car should not sit on the stops hence there is an issue. the bags may have given out or it may be the valves at the compressor end. one way to check the bags is to spray them with soapy water and see if there are any holes although this will not work if the hole is under the fold. sometimes the fold will also cover up a hole and air will only escape if the car is at the right angle.

suggest you get it checked out asap as the compressor will be working overtime and they are expensive to replace.

Sorry cant see pic as the company firewall blocks it (i should be working anyway)

But wots s'ppose to appen is that even with the the engine off, opening any door (including rear) will set of the SLABS ECU into monitoring the height for half an hour. (yes it lives, even with the key out, freeky eh!)

The idea is that when you unload the camping gear/beer/7 adults, the rear will spring up. The height sensors notice this and tell the SLABS ECU that we're way too high now, which in turn will send a signal to the Compressor to vent air (big psssssfttt can be heard) to get the car down to within 20mm of the target ride height, ie normal height. This 20mm could be either +20mm or -20mm of the "normal height".

Sinking to the bump stops is a bit too low, suggesting;
1. Height sensors need calibrating
2. Airbag leaks
3. SLABS ECU needs re-programming.
4. Vent valve leak in compressor

My bet is #2.
Does it sink when the doors are shut, if so, its 99% certain to be #2.

Let us know what the diagnosis is.

I've a ton of experience now (not by choice ) changing compressors and airbags over.

Originally Posted by simonl8353

Sorry cant see pic as the company firewall blocks it (i should be working anyway)

But wots s'ppose to appen is that even with the the engine off, opening any door (including rear) will set of the SLABS ECU into monitoring the height for half an hour. (yes it lives, even with the key out, freeky eh!)

The idea is that when you unload the camping gear/beer/7 adults, the rear will spring up. The height sensors notice this and tell the SLABS ECU that we're way too high now, which in turn will send a signal to the Compressor to vent air (big psssssfttt can be heard) to get the car down to within 20mm of the target ride height, ie normal height. This 20mm could be either +20mm or -20mm of the "normal height".

Sinking to the bump stops is a bit too low, suggesting;
1. Height sensors need calibrating
2. Airbag leaks
3. SLABS ECU needs re-programming.
4. Vent valve leak in compressor

My bet is #2.
Does it sink when the doors are shut, if so, its 99% certain to be #2.

Let us know what the diagnosis is.

I've a ton of experience now (not by choice ) changing compressors and airbags over.

Hey Simon/ Tip...thanks for that...thats just it....it hasnt sunk for 4 days now. Surely if it were a leak it would happen all the time?? When it does go down it happens nearly every time. Then for whatever reason it doesnt happen for days...ie when I hardly if ever open rear door...which I dont think I have over the 4 days

Regards

Stevo

I had a similar probem, but mine would only go down on the one side - all the way to the stop by opening either the rear or back doors (It was quite happily sitting level, open the door and pffft, down it would go). The other problem was when off roading it would slowly leak down on the one side even though the car could sit for month and not go down. Turned out to be the bag being slightly porous at the fold, so at normal ride height it wouldn't leak but when off-roading it would to a point where the compressor would cut off (it has a maximum number of cycles before it cuts out to prevent overheating). I found the leak by squirting soapy water when jacked up on the tow bar to expose as much as possible of the bag. I ended up replacing both bags and getting the ECU cleared, I did nothing to the height sensors (there were heaps of fault codes including the compressor overcycle an a height sensor fault), has been perfect since.

I would go for Airbags to being the issue to.

Mine would do it randomly aswell, but mostly on one side, but then it would "sense" the difference in the height settings and drop the other side to.
New bags fitted, been fine since "touchwood". I did a write up for replacing them as well, its a pretty easy task to be honest.

www.discovery2.co.uk / Rear Suspension Air Bags

Maybe it was programmed by the dealer when new due to the owner being vertically challenged?........be easy to get the shopping out.

I had a similar probem, but mine would only go down on the one side - all the way to the stop by opening either the rear or back doors (It was quite happily sitting level, open the door and pffft, down it would go). The other problem was when off roading it would slowly leak down on the one side even though the car could sit for month and not go down. Turned out to be the bag being slightly porous at the fold, so at normal ride height it wouldn't leak but when off-roading it would to a point where the compressor would cut off (it has a maximum number of cycles before it cuts out to prevent overheating). I found the leak by squirting soapy water when jacked up on the tow bar to expose as much as possible of the bag. I ended up replacing both bags and getting the ECU cleared, I did nothing to the height sensors (there were heaps of fault codes including the compressor overcycle an a height sensor fault), has been perfect since.

Thats essentially what Smokey has been doing...seems to drop right hand side first and at some stage followed by left side.

Maybe it was programmed by the dealer when new due to the owner being vertically challenged?........be easy to get the shopping out.

I thought it was for easy access to beer in fridge ala:



Regards

Stevo

if one side is going down first then it is most likely the bags. bet if you park it on a roadside with a fair camber then the back will drop. the shift in the mass of the car will open up the fold a bit and let the air out.

you are also hearing the compressor cycle after the engine is turned off??? it goes in short bursts of about 2-3 seconds. this also suggests leaking bags.

on level ground the bags tend to seal themselves therefore you may not see the car drop if its parked on level ground.

probable that the compressor is working overtime. my understanding is that the compressor will time itself out if it gets overheated. possibly why you have seen it bottom out whilst driving.

bags are fairly easy to replace if you can get your hands on a couple of trolley jacks.