Rb20 Ecu Red Light Stays On

[RUSTY_01]

jsut finishing off putting a rb20det into a mates 31. the engine and wiring has already been in a running in a 31 before the swap again, problem is the light on the back of the ecu is on red no flashing blinking, what does this mean? ive found the foult codes but no explaination of solid red light on. and help apprectiated grately, thanks rusty