i will get shot for this!!
£50
Manual Suspension Override - Range Rover P38 - EAS AIR | eBay
pulled this from the web will cost about £5
1. Disconnect the battery first
2. Remove the lower plastic around the BECM
3. Locate the positive brown wire on the front of the BECM
4. Locate the black at the rear of the BECM
5. Look at front of BECM toward the glove box. Locate the second green connector from the door and unplug.
6. Locate the blue and pink wire going to the connector. Clip the wire.
7. Connect BLUE and PINK wire to GROUND. Be sure you connect to side that goes into the plug, not the end that goes to the connector.
8. Locate blue and white wire. (Be sure it is primarily blue with a white stripe, not white with a blue stripe.) Clip the wire
9. Connect the BLUE and WHITE wire to the positive using a 5amp inline fuse. Be sure you connect to side that goes into the plug, not the end that goes to the connector.
10. Close off the open wire ends with electrical tape or wire caps to avoid shorts.
11. Plug the connector back into the BECM.
12. Go under the hood and locate the fuse box near passenger/left side firewall.
13. Remove relay RL20
14. Go to the drivers/right side firewall and disconnect compressor plug.
15. Reconnect the battery
16. Start the truck and you should see EAS MANUAL on the dash.
These are the instructions from Arnott.