Land Rover LR3 Air suspension

Your LR3 has a somewhat complicated air suspension system, but no worries, here I wrote an article on how it works, features and some common faults. The air suspension system consists of the following parts:

• Air suspension control module
• Air compressor
• Compressor relay (in the engine compartment by the battery, controlled by the air suspension control module)
• Height sensors (one per wheel)
• Valve block assemblies (two for each front and one for both rear)
• Reservoiur (tank where pressurized air is stored)
• Air springs (one per wheel)
• Pipes connecting all the above together

In a nutshell, the computer is constantly looking at the four height sensors of the car, and redirecting the air from the reservoir to the air springs via valves in the valve blocks. The two front can be adjusted independently and the rear are adjusted together. The compressor comes on to keep the reservoir full when certain conditions are met. Remember that the compressor draws a lot of juice from your electrical system so it can't constantly run.

The system allows you, the driver, to select three different ride heights via a switch located in the center console. The system will give you feedback on whatever is going on via the instrument cluster. These ride heights can only be adjusted when the engine is running and the doors are closed. There is an exception to this rule, you can lower the suspension into what they call "access height" after you shut the car off. However this will only work for a little bit after you shut the car off, and before you open the door.

Now the three selectable heights for the suspension system are:

1. Normal height: this is like your regular middle height.
2. Off road height: if you press up on the switch the vehicle will rise and your rover is now ready to do what is what meant to do, can only be selected when the vehicle is doing less than 25 mph. When the vehicle reaches about 25 mph, the car warns you to slow down or the vehicle will lower.
3. Crawl height: if you press down on the switch the vehicle will lower so you can access those annoying low roof parking lots (here in Miami those are pretty popular). Access height is this height but access is selected by  lowering the car before 40 seconds after you shut it off, if you come out of the car at these height the vehicle will stay like this until you comeback and change it. A couple of warnings: if you select this height from off road, the car will come back to off road. If you exceed 6.2 mph, the car will return. So watch out for that roof. If you are going faster than 12.5 mph the car will wait for one minute until your reduce the speed. After one minute the request will be canceled. Crawl height can be selected while driving and will stay until you exceed 25 mph. To select it, hold down on the switch.

There is also another mode, transportation, but this can only be selected via the dealer scan tool. I've seen a couple of cars come into my shop with a car that somehow, magically, got into transportation mode. We have the Land Rover scan tool and changed this (for free because I'm not a douche-bag) and to this day I can't explain this glitch. But beware that this is possible, although I've only seen it twice in about eight years I've been doing this. Transportation mode locks the vehicle height so that it can be safely transported, when the vehicle is shut down, the suspension lowers and when you start it up, it goes up. All these up and down action comes with chimes in the dash.

Another cool feature (this one not a lot of people know about) is that you can program the remote of your car to switch the ride heights with the car off to assist you in hooking up a trailer (for example), or showing off or whatever.
Here is how to do it (of course I'm gonna tell you how to do it :D):

Your remote has three buttons: Lock, Unlock, and the third button is called "personal button" (funny name). This personal button can be programmed to do a couple of different things, programming it to do one will overwrite the other so whatever it is that it does now, it won't do it when we are done (beware!). So with the car running and sitting in the drivers seat with the doors closed shut the car off and remove the key. Hold the personal button and the air suspension button in the height you want the button to perform until you hear a chime. When you do let them go. That's it, have fun with that feature.

Another feature of the system is that it can sense if one of the wheels lost traction and adjust the height of that wheel accordingly, to increase traction. A message will be displayed in the dashboard if this was to happen so you'll know.

The system checks itself for faults too. There are two types of fault, hard faults and soft faults. Hard faults are usually accompanied by the "Air suspension fault" message of doom (doom for your wallet that is). Soft faults give you an amber light and an annoying chime (but still have wallet dooming capabilities).

There is a high speed mode, which basically lowers the car a little bit as you increase to higher speed to increase aerodynamics.

After two hours of being parked the car wakes up and readjusts the suspension. It does that again every six hours.

There is a calibration procedure that should be performed with the dealer scan tool (the claim it should be done I've never had to do it or seen a problem that requires it). This calibration should be performed when you change the module, a control arm that attaches to a height sensor, or a height sensor. Anything else doesn't require calibration.

The computer for the suspension receives data from the four sensors at each control arm in each corner of the wheel, and a bunch of data from the CAN network like steering angle, acceleration, side-to-side acceleration and wheel speeds. If one is missing then the computer assumes a default value and starts acting all weird.

The compressor and height changes will not work if:

• the compressor is too hot (it has a temperature sensor, it could get hot cause you been playing with the suspension too much moving it up and down when you shoul've been picking up your kid)
• hard cornering is detected (you are drifting cause you forgot to pick up your kid)
• hard accelerating is detected (your wife called you asking where the heck is your kid)
• hard decelerating is detected (entered your kids school zone)
• jacking up of the car is detected (you can't find your kid, might as well look if he is down there)
• a door is open (find your kid, took him out with the door so he won't remember and rat you out to your wife)

So as you can see your suspension system is ready for all kinds of scenarios with your kid and many driving conditions. Now you have a better idea of how it works.