abs warning light on.

hello,



I was driving my laguna concorde K56 the other day when the abs warning light came on. The inboard computer told me that there is no abs but the brakes will still function normally.



I have looked in the haynes manual to see if I can bleed the brakes as I had a new axle fitted a few months ago and the brakes are a very little bit spongy:



The book told me that it has to be done by a renault dealer as they have the diagnostic equipment. is this correct=



I also wanted to check the sensors to see if they are functioning correctly but I am unable to find out what the resistance should be.



Or does anybody have any ideas what it could be?



Thanks in advance



David