Land Rover Suspension Calibration
Quite often I get called to calibrate the suspension on Land Rover vehicles after the compressor has been exchanged. I am sure many of us have learned new words when going through the process. First we need to make sure the correct calibration is in the Ride Control Module. There are two different compressor calibrations. The Hitachi and AMK. The Autologic tool will tell you which file is installed. If you have a Pro subscription you program the correct calibration if needed. Another nice thing about the Autologic tool is that if you get the measurements wrong, it will tell you how far off you are. I have not seen any other aftermarket tools that do this. Please let me know if there are others.
For this article, we are using the Autoland Scientech Iscan IIwt. The tool has the ability to change the type of compressor in the ride control without an extra subscription. The programming files need to be manually added to the tool when needed due to limited drive space. The above listed vehicle already had the correct calibration.
Something that has been difficult in the process is finding dead center on the wheel cap for the measurement. (explanation below) Since the system only allows a allowance of 3mm, you have to be quite precise. The Autoland tool will not tell you how much you are off, only that you have failed. I have spent hours trying to get a calibration when using a metric measuring tape. Even longer when trying to convert to metric when using an inches tape. Finding the center of the cap was not consistent. I know there are special tools from Land Rover. So far I have resisted in purchasing them. One option I have seen online is a company takes a new center cap and cuts a groove down the middle. You pop the new cap in and the measuring tape end fits snugly for a precise measurement at the wheel arch. What I figured out was that the caps are about 66mm across. My new method is to add 33mm from the top of the cap to the center of the arch. This seems to work quite well. This method also helps with aftermarket wheels. Most aftermarket wheels do not share the same machining as the OEM wheels so the factory tool and above mentioned caps would not be useful. My method gets the job done fairly simply.
For the calibration, the vehicle is put into learn mode with a tool capable. This calibration is done while the engine is running. The software has you measure each corner in millimeters from the center of the wheel cap to the top inside of the wheel arch. Once each measurement is input, the vehicle will rise to the off-road level, then drop down to normal ride height. The software then has you input the measurements again. If the second set of measurements equals what the software expects, then the calibration is complete. If not, the software will attempt another try. If you fail again you have to start all over.
By using the method of top of wheel center cap to inside wheel arch and adding 33mm, the repeat calibration attempts have gone to maybe two times average. The last vehicle it took on the first attempt. Sorry about no pictures this time. As in many cases always in a rush to get to the next appointment.
I do something similar, I deduct to distance from the bottom of the rim to the middle of the center cap. I find it easier to hook the measuring tape to the bottom of the rim. It still takes more than one attempt sometimes. Next time I will try your method maybe I will have better luck, Thanks.