So after further review it seems that I'm getting the P1590 because of a failure in the Self Levelling & Anti-lock Braking System (SLABS) ECU. When we bought this 2001 D2 the last owner has removed the airbag leveling system and installed coil springs. Of course now the leveling system no longer works. Is there a work around that will keep the truck from throwing this code????

 

What are you using to read that code? You need an ABS reader that will read Land Rover ABS codes. The 1590 is a generic code that some readers pick up.

 

The ABS and SLS have nothing in common,
If you are getting a 1590 fault code number, Rough Road/ ABS failure, you need to get the proper reader and find the problems leaving the SLS and SLABS alone for now.