trafic immobliser

hi i hope someone can help me am new to the site but not to renaults, i have an 05 plate trafic that wont start and i have no c/l no indicators no interior light but most importantly no immobiliser light. i tried the uch and key and ecu from another van and no change, when i switch on the ignition the the spanner light continues to flash but no immobiliser light at all and van will spin over but not fire and also have no power at the diagnostics plug, am tearing my hair out here have tried fuses relays and traced nearly every earth but no luck, any fresh ideas welcome