I have a '99 Disco II and the rear air suspension does not work. Yesterday the compressor would not shut-off even when turning off the ignition. I had to pull the fuse to get it to stop. I removed the two lines that come from the air valves and no air is coming out, even when the compressor is running, but it does come out of the middle line which supplies air to the valve block.

Could this be a bad SLABS ECU? As I recall the compressor should not run with the ignition off (normal ride height mode)

 

coil conversion.

 

the compressor does work with the ignition off i think as you can purchase a key fob with the controls for the SLS on it, ideal for hitching up a cvaravan etc.