go back on

[go back on] {v. phr.} 1. To turn against; not be faithful or loyalto.

Many of the man's friends went back on him when he was sent toprison.

The boy's father told him not to go back on his promise.

Compare: BACK DOWN, TURN ONE'S BACK. 2. To fail to do necessary work;not work.

Grandfather's eyes are going back on him.

Compare: BREAKDOWN(4), GIVE OUT.