Friday, January 30, 2009

Land Rover LR3 Extended Mode

I'm very happy these days. This is because I finally found a way to hack my truck's suspension. The LR3 has an air suspension that can put the truck into 5 different ride heights. On the surface, that sounds great. Unfortunately, the driver cannot control all of these options.

The normal ride height, used in everyday driving, provides a minimum ground clearance of 7.3 inches. You can lower the height to "Access Mode" making it easier for people to get into and out of the vehicle, and providing more roof clearance when driving into parking garages. You can also raise the height to "Off Road Mode" and get a minimum of 9.5 inches of ground clearance. The driver cannot directly raise the vehicle any further, even though there are two higher modes. This is annoying for me because I enjoy driving on some challenging roads where I'd sure like to have an inch or two of additional clearance. I've tapped several boulders already and have a small dent in my exhaust pipe from another boulder.

The next higher mode is called "Extended Mode" and is engaged automatically when the computer detects that the truck is high-centered. It does this by sensing the pressures in the 4 wheels' air canisters (I think). Then, once you're in extended mode, the driver can go into "Super Extended Mode" and get even more clearance by holding down a switch for 5 seconds while pressing the brake. Note: that's my name for it; the manual (page 176) does not name it.

I've been googling for many months to find a way to hack the computer that controls the suspension. I wanted a way that I could engage extended mode. But, I didn't want to void my warranty either. I discovered that I wasn't alone. Many other LR3 owners are seeking the same prize. One clever guy has found a way to swap out part of the mechanical sensors that read the height of each wheel. Others have successfully hacked the 5 data buses that are used by the various computers in the vehicle. There are definitely some very smart and determined people out there. Then finally, I stumbled upon an elegant solution that a few owners use. A trick, really.

My friend, John, gave me a block of 6x6 wood that's about 10 inches tall. I simply raise the truck to off-road mode, then place the block under a lateral frame member. Then I lower the truck to normal height. The LR3 lowers onto the wood block and that makes the computer think that it's high-centered. Then the computer raises the truck to "Extended Mode". Yay! Then I can, if I want, raise it up to the final (greatest) height.

So, the photos here document that simple trick. The first pic shows the truck in normal street height. The second pic shows the truck in "Off Road" height. The third pic shows the truck in the highest possible height (the one I called "Super Extended Mode" above). The last two pics show the block of wood underneath the truck, first while in off-road height, then while in super extended mode. It's clearly not a huge gain in height. But every bit helps. I plan to do this again and measure the heights with a tape measure - just to see what the actual difference is.

Anyway ... I'm happy because I now bring this block of wood with me on the trail. Then, if I think it's needed, I'll raise the truck a bit more before crossing the most challenging boulder patches.

Footnote: For the record, I'm not a fan of the LR3's suspension. I would much prefer 2 height settings: normal road height at about 8 or 8.5 inches minimum clearance (comparable to many SUVs and CUVs), and off-road height at about 12 inches clearance. And the driver should be able to control this.


Island Rover said...

Did you get to meassure the total achieved height?
Will the suspension auto-lower out of the 'super' setting?

michael said...

I measured the height below that lateral frame member. In "off road" height, it was 10 inches. And in "extended mode" it was 11 inches. Certainly not as much as I expected, or hoped. But I welcome being able to add that extra room when I need it.

I imagine that it will automatically lower itself, however, I haven't seen that in my craptacular testing. I got the truck up to 15 mph, then ran out of parking lot. I really need to redo that test on a quiet residential street.

paul said...

it works! i used a cinder block and a cement path stone to get enough height to fool the sensor. what other secrets is the lr3 keeping from us?

Michael said...

I've made some measurements of the ground clearance under my 2015 LR4 in this new post: