A failure in the anti-lock brake system (ABS) causes the ABS pump to continuously run, which will eventually wear down the battery. An improved ABS relay is available to solve the problem.
Average mileage: 199,984 (135,000–300,000)
20 people reported this problem
After husband slammed on brakes multiple times in a few minute span the abs light came on. Then the humming sound stayed on after turning off car. I figure it is ABS pump running continuously or something wrong with the relay. Will pull ABS fuse to see if that will stop the pump from running so it won't drain the battery tonight.
ABS warning light illuminated on the dash. I googled "abs light on 1991 subaru legacy" and a link (this page) said that a common problem was the relay burning up and causes the ABS pump to run continuously (even with ignition off). Haynes manual revealed the location of the ABS relay. Replaced relay with new one. Problem fixed:)