Interesting Issue with Jacking - be aware!

[Jpdv]

For those who are interested.

I was preparing the car/shed for some underbody work yesterday.

Put my heavy duty trolly jack under the rear central cross member. Car in off road height. Jacked up. Fiddled about with rear diff. After removing axle stands, went to gently lower trolley jack: this is where it got interesting...

I think I lowered too slowly. As a result, the car (which was switched off) seemed to trigger some sort of suspension adjustment, and just kept coming down with the jack. To the extent that the spare wheel started fouling the trolley jack arm, at which point I realised the vehicle was almost touching the wheels at the rear arches.

I stopped in a panic, convinced I'd crushed a suspension hose or some such, and got in. It displayed 'extended mode' on startup, (despite having gone into what I would describe as 'super not-extended mode') at the back. pressed normal height, and it reverted happily.

I think that the issue was some sort of singing loop where the suspension was sensing the jack as I lowered it, and constantly adjusting down for some reason. Worth being aware of - if I'd casually left a tool box or the like under the back end, either it or the part of the car above it would have been crushed before I noticed what was happening.

[jwb]

Good idea is to pull the fuse on the air suspension system (fuse box in the engine bay) while working underneath as well as putting stands under the chassis arms which you did.

[josh.huber]

For those who are interested.

I was preparing the car/shed for some underbody work yesterday.

Put my heavy duty trolly jack under the rear central cross member. Car in off road height. Jacked up. Fiddled about with rear diff. After removing axle stands, went to gently lower trolley jack: this is where it got interesting...

I think I lowered too slowly. As a result, the car (which was switched off) seemed to trigger some sort of suspension adjustment, and just kept coming down with the jack. To the extent that the spare wheel started fouling the trolley jack arm, at which point I realised the vehicle was almost touching the wheels at the rear arches.

I stopped in a panic, convinced I'd crushed a suspension hose or some such, and got in. It displayed 'extended mode' on startup, (despite having gone into what I would describe as 'super not-extended mode') at the back. pressed normal height, and it reverted happily.

I think that the issue was some sort of singing loop where the suspension was sensing the jack as I lowered it, and constantly adjusting down for some reason. Worth being aware of - if I'd casually left a tool box or the like under the back end, either it or the part of the car above it would have been crushed before I noticed what was happening.

I left my air compressor under my car once and let it down.. It wasn't very happy

[RANDLOVER]

Good idea is to pull the fuse on the air suspension system (fuse box in the engine bay) while working underneath as well as putting stands under the chassis arms which you did.


...or leave one of the doors open, I'll get my popcorn. [bigwhistle]

[davros]

...or leave one of the doors open, I'll get my popcorn. [bigwhistle]

Interesting!
Perhaps the sensors think it’s “too high” whilst jacked and let it down down down as of course it doesn’t go down… Then the system shuts down with its dying “thoughts” being that it’s still too high. Door open and it doesn’t try to adjust for passenger safety.
I dunno. I don’t have these issues on my ex-military SIII lightweight. My issues are more like, “I took off a front shocky, noticed it was devoid of any function nor seemed to contain any fluid, replaced it, and feel no difference [ride totally akin to horse and buggy before and after]”.