Hello gents,
I want to ask is it okay installing ASU (air suspension module) from old car contains 4 hight sensors on a new car contains 3 hight sensors.
Both cars XJ8 one is 2003 model and the other 2008 model
Thanks in advance 😊

 

I don't know for sure, but I would think not. I don't know what it would do with the missing input.

Logically, the three-sensor systems can calculate the height of the missing sensor, because based on the three it has, unless the car twists, the sensor-less corner can only be at one place. I rather doubt that such programming is in the 4-sensor module.

All that said, that's me speculating, not spouting actual knowledge. I would expect a fault light on the dash, though.

 

Believe your right, the front right sensor was eliminated sometime in 04 the first year

 

Braq33;

Taking a quick look at Fig 5.3 on the 04' electrical Guide (x350) and the 08' Electrical Guide (x358) the number of height sensor inputs varies. There is a note in the 08' Guide that the RH Front sensor is not installed.
I seem to recall reading that at some point the wiring loom eliminated the circuit for the RH front sensor. You could look to see if you have connector in place for a 4th sensor but then the question becomes "Will the 4 sensor ASU communicate correctly with the other control modules in your otherwise 3 sensor car?" Its starting to sound like more of a science project and there is risk it may not work out.

I'm thinking like wfooshee and Wingrider this is not a simple swap. Perhaps if you were going the other way; a 3 sensor ASU installed in a 4 sensor car.
It would still be interesting to see if the 3 sensor ASU communicated with the other control modules fluidly.

You might reach out to Motorcarman, Bob Gauff on this forum. Bob seems to have experience with what you can, and cannot change, in the software/firmware.

Best Regards, William