ticky jacking due to air suspension ..
 

Hi,

I jacked my car when I heard the air suspension blow.
My car sunk down, due to that strange mechanism, which is triggered by detection of a jacking attempt.

Call me stupid, but what is the intended use of releasing air while jacking the car ?
It seems to me like sabotage on my repair attempt, and completely useless.

:icon_tinykitball:

where was your jack? under the body, or under a suspension part?

Did you have the ignition on

The car wont know you are jacking it up and attempt to level the suspension
You will hear the purge valve lower the pressure and the opposite when you lower it down

Cheers
34by151

I was using two floor jacks on the inner jacking points according to the workshop manual.
If I fail to keep balance while lifting, the air escapes.
Ignition was off, handbrake was on.

Can I tell my cat not to loose air while jacking ??
Disconnecting the battery is not my prefered way, as alle FM-stations get lost...

It should time out itself after about 10 seconds if it finds that bleeding air is having no effect. It should then disable further adjustments until either the car exceeds 2mph or returns to the correct level.

I wonder if pulling fuse 52 in the luggage compartment fuse box would help because that is the one for the air suspension module.

A common objective is changing a flat tire, an exercise quite often done on less-than perfectly solid or level ground. For that, one does NOT want to have to jack the chassis to a shakey perch up in the stratosphere because the air-suspension keeps pushing the wheels further out. A Citroen DS-series with a self-lifting mode, it is not.

For jacking up to perform general repairs on a good surface, pulling the compressor fuse sounds like a winner to me ... though MANY repair procedures on a motorcar start by specifying the battery be disconnected anyway, so...

The air suspension module has a jacking mode

From JTIS
************************************************** *************************************
Jacking Function
When the system detects that the vehicle is being jacked, or raised on a wheel-free lift, the vehicle enters jacking mode, which inhibits lowering to prevent air loss.Jacking mode is exited when the vehicle is driven, or the ride height passes below a threshold value.
************************************************** *************************************

The air suspension module gets battery and switched power (96S)

You have no power from 96S if the ignition is off however 96S is controlled by power relay 4 in the rear fusebox.
Relay 4 supplies power to fuses F11, F12, F13

The Fuse you want is F12 that is the one for 96S but all you are doing by pulling this is telling the air suspension module that is ignition is off

To stop the air suspension you need to pull its battery power
The most obvious way is to remove the battery lead next is to pull the plug from the air suspension module but this needs you to remove the rear seat cushion and flip down the backrest. This is easy when you have done hard the first time to work it out. These days it takes me a few minutes to do.
Another way is to pull the 20amp fuse from the transit isolation relay. This is the battery supply for the air suspension module. This fuse is not connected to any other modules so will only disable the air suspension. This is located near the battery. The main positive battery wires goes through the transit relay and then connects to the 3 megafuses so its easy to identify

Depending on the PDI that was done you may not have the transit relay at all. If you dont you can locate the wire that runs to the air suspension and just pull the connecter. You could also fit an isolation switch inline if you plan to do this a lot


Hope that helps

Cheers 34by151

If the PDI was done properly then, as you say, the transit relay should have been removed and an in-line connector reconnected that is intentionally left disconnected at the factory, otherwise circuits will remain live for a bit after the ignition is switched off.

That should just leave F52 supplying battery power to the ASM so do you not think disconnecting that fuse would work?

Disconnecting you need to also disconnect F12
IE you need to remove both the switched and battery power from the module

This will produce the same ting as using SDD and putting it into Shipping mode

If the module has battery power (F52) and the ign is off (F12) for 30 minutes its goes from normal mode into sleep mode. The prevents the suspension lowering hower it will raise the suspension rapidly . This is to combat overnight leaks. Sleep mode is turned off autocratically by ignition power.
The module will also go into jacking mode after you start jacking. I posted the jacking mode details in my last post.
This means it initially tries to level the suspension then gives up. So some adjustment while jacking is done which is what you have seen

To stop all of this you need to remove both battery and ignition power your options are
1. SDD and enter shipping mode
2. Remove Battery
3. Disconnect module
4. Pull fuses F52 and F12
5. Fit an isolation switch to interrupt power from F52 and F12

All of this is detailed in the JTIS it would be well worth you while to download a copy of this and JEPC also a mongoose SDD is a very useful tool

The links to these are easy to find

Cheers
34by151

ThnX a lot for your helpfull comments.
I'll try the "pull the fuse"-way next time.

As my floor jacks are close to 5mm to my car's body, the slightest loss of air forced me to start the engine to get my floor jacks out again.
In Jtis the front jacking points are very deep under the car and I'm not sure, if its a good idea to put a floor jack directly under the door, where the onboard jack attaches..
Am I the only one that uses the "correct" jacking points from Jtis ?

I agree, I got my first copy of the JTIS over 10 years ago and the JEPC is a welcome replacement for the previous parts system and MUCH easier to use than the parts micro fiches :)

The training guide given to Jaguar technicians when they were being trained on the X350 is well worth hunting down as well as it has a lot of detail not in the JTIS and nearly 200 pages more than the Technical Guide.

I don't have an X350 to play around with any more but I am still struggling to see why we care about fuse 12 if the ignition is switched off whilst jacking the car up.