1997 Grand Caravan gauge problem-HELP

Recently I got 97 Grand Caravan. When I test drove it the ABS light
stayed on. When we checked it back at the shop, after restarting it, the
light was off. They checked it out and replaced the rear brakes and all the
hardware as well as turning the drums. It's been fine for the last few days,
but today when the automatic door locks kicked in at 15mph, the ABS light
came on, digital displays began to flicker, the gauges dropped and
recovered,and a minute later the battery light came on. When I got home and
restarted the car, all seemed to be back as it should be. Seems to me it
might be electronic related. Does anyone have an idea where to start looking
for the problem. I'm going to recontact the dealer tomorrow and would like
to have some idea what to tell him. Thanks in advance for any insight into
this problem.

Jay