Legacy Outback

Failure in ABS causes pump to run continuously and wear down battery on Subaru Legacy Outback

Problem Description and Possible Solution
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.
Problem Data
RepairPal Verified
Average mileage: 176,333 (85,000–265,000)
5 model years affected: 1995, 1996, 1997, 1998, more1999
16 people reported this problem
Viewing 1 - 8 of 8 comments
The ABS unit made a constant droaning sound whether the car was on or off, and the ABS light was on. The problem was fixed by tapping the black box (the box that contains the ABS relays) with a hammer. This will give you time to get a new relay, or in my case, fix the problem. I've had no symptoms for 6 months since this happened.
My Mother has a low mileage Impreza, it's actually a 1993, with 74,000 miles on it. The problem of the ABS pump relay sticking also effects these models. As far as I can tell, the parts are identical. The fix is simple...recharge the drained battery, open up the engine compartment fuse box, and remove the 45 amp ABS fuse. The relay is on the left front of the engine compartment over the fender, pop off the black plastic lid that is attached to the ABS assembly and over where you heard the noise from, and the relay is the component towards the front. The Subaru part # is 26735AA012 ($45.00) and you can pull the old relay out, replace it with a new relay, and then replace the 45 amp fuse that you had previously taken out. Our local Subaru dealer had tried to take advantage of her by telling her that the entire ABS assembly needed to be replaced...I'm glad she called me before having the dealer fix her car. The whole process (except recharging the battery) from start to finish is about 15-20 minutes.
My ABS light came on while I was driving. I went home and went to bed not thinking about it. Car was dead in the morning, took 10+ minutes to charge enough to jump, but you could hear the ABS system turn on as soon as we connected the cables. Left it sitting overnight again, you could hear it running the whole time but I had no idea. Came out again and it was dead, wouldn't jump this time. Then I read these comments, went out and unplugged the part mentioned in the comment below and it jumped immediately. It's been fine since, but the ABS light is still on. I haven't ordered the replacement part yet.
abs pump continued to run, had to disconnect battery. waited 15 minutes. reconnected battery, problem hasn't returned.