ABS Off Light ON

[Mark Pollan <0002009911@mcimail.com>]

Just replaced the driver's side rear wheel bearing on my '86 5KCSTQ.
Sweet silence.  The problem is that now the ABS Off Light comes on.  I
can hit the ABS switch and it will go off but will come back on in
about 15 - 30 seconds.

I did not replace the little plastic cap on the speed sensor and as
such did not seat it as far as it would go fearing damage.  I will
pick some caps up and re-seat it but do you think this is the likely
cause or something else?

TIA

Mark

P.S.  When replacing the bearing all went well except getting the inner
race off the hub.  Had to take it to a local shop to pull it off. 
Seems the arms/hooks on my standard puller are too fat/rounded to get
into those little notches in the hub.  Is there a puller out there used 
specifically for this or do you all just modify a "standard" puller
to fit by grinding down the hooks a bit.  I need to do the other side
and would like to avoid going to the shop 25 miles away.