calibrating air suspension
 

After having my ignition replaced at the dealer, they returned the car to me with one air bag fully inflated to off-road height. Needless to say, I was not pleased, as this is a potentially dangerous situation. It failed to drop even at speed. So, I returned to the dealer hoping they could do a simple calibration adjustment, as this has occurred there before. It's now been a week, and they are telling me that their T4 so rarely gets used that the cable does not appear to working. Can anyone please recommend the most affordable software or device that would allow me to adjust air suspension levels. I realize there might also be a failed height sensor at play as well, but I believe that still requires calibration after install. Thanks!

It sounds like you have one of the SLS leaking. Try the Offroad button with all the doors firmly closed and once it reaches max height then get out of the D2 and check for any hissing on the SLS you believe is not working correctly. Afterwards press the Offroad button to lower the suspension. (no guarantee this will work) Setting up the SLS height doesn't require any software or diag tool just the 2# setting blocks from an LR main dealership. IMHO you have leaking rear suspension SLS which requires total replacement.

IMHO your garage and their mechanics sound like a bunch of numpties.

Setting the SLS height DOES require a scan tool capable of programming the SLABS.
I borrowed a Hawkeye and was able to adjust the height of each bag individually and test the entire system, but it could not write new baseline values.
The blocks give you a reference height for you adjust to your bags. They do not do anything electronic. As soon as you turn the key off and back on again, any changes you make to the height will be lost unless you program them into the SLABS.

Hi Mollusc

If the SLS sensors have never been disturbed before they shouldn't need calibrating in the SLABS just height checking with the setting blocks. Re-calibrating is only for one or other sensor replacement or someone been playing with the sensors. Even replacing both of the air suspension bags doesn't require re-calibration of the sensors. The air bags don't determine the final running height the sensors do that via the SLABS and subsequently the compressor.

In theory, that's correct. However, having done both a double bag replacement and a double rear shock replacement relatively recently, I found that everything was lopsided after both actions (to different degrees both time). At no point did I do anything to the height sensors.
And then I switched my SLABS unit so naturally it was off a third time. Changing to coils and turning off the air completely solved the issue, of course.

Thanks, guys. I could see why you's suspect and SLS leak, but that's not the case here. One bag is normal height and the other is FULLY inflated.

I did try raising and lowering and it inflated the normal ride height bag, but did not drop the other one. Also, driving at speed did not drop it as it is supposed to. Sounds like a Hawkeye will do the job, but $$$$$. Anyone near Allentown, PA have one and able to help me out? Also, wondering if maybe I should just replace the height sensor. It seems more like that disconnecting the battery would throw off something in the SLAB that a coincidental sensor, but anything possible. Thanks!

Could the air vent from the inflated bag be blocked?

A Hawkeye will allow you to view the height values that the SLABS is reading from each side, which would tell you if the sensor side of things is working properly. It will also allow you to adjust the heights on each side separately in a test mode. However, if there's something wrong with the air release system then the Hawkeye isn't going to be able to fix it.

Have you ever replaced the SLABS? If you have it's possible the new/used SLABS has different mean reference points that control the levels sensors. That will definitely require intervention using a suitable diag tool to reset the SLABS mean references related to the existing sensor positions. Be careful which diag tool you buy as most/many cannot reset the SLABS as they are 'read only'.

Thanks, OffroadFrance. I never replaced the SLABS.

The Allentown, PA dealer finally got their T4 operating. The truck has now been there close to TWO MONTHS! They phoned yesterday and said they have three hours in it (not charging me, thankfully) but when they reprogram the height it is okay temporarily, to drive around the block. Then, they restart the car and one side elevates fully again. It won't remember the height. I think this rules out a blocked air release, since it does seem able to release air.

The dealer said it is possibly a height sensor or in their opinion an electrical harness issue, which they say could cost a fortune to trace. Basically, they said unless you want to spent a fortune on this thing, come and take it away. We can't fix it. So, I have a new $1,000 ignition on a lop-sided truck.

I have heard that failed height sensors can cause full inflation. That's one job I've never done, but I'm inclined to give it a try. I'll check Atlantic British for parts and a video, but any advice appreciated. e.g. Should they be done in pairs? Will it require programming? If that fails, I'm ready to move to coils.

Thank you all!

The rear height sensors are as cheap as chips, the pair will cost you only around $50-60. (I hope ;)) It sounds like a sensor or the compressor solenoid valve hanging up. The sensors should come complete with arms and drop arms. TWO MONTHS! they could have fitted a galv frame in two months and only working part time!