Found the identical symptoms on this thread
http://www.peachparts.com/shopforum/tech-help/76140-w124-abs-dash-light-start-up-sequence.html

But the 400E is significantly different in layout. There does not seem to be a ABS relay, There is an ABS module in the module box where the 38 pin diag connector is. Any experience on doing a diagnostic to see if the cause is there?

Oh -- changed all the fuses to better newer brass/copper versions, no change.

paul