reault scenic1997 immobiliser?

Renault scenic 1997 model.
When i flash my headlights my immobiliser keeps cutting in.it goe's to cut my engine off but shudders and keeps going it has only just started to do this when i took my battery off to check
the levels.I have checked all fuses,earth leads battery terminals
and relays. But still no joy.Please can you help.