"took a pledge" is correct and usable in written English.
You can use it when someone has made a promise or a commitment to do something. For example, "The candidate took a pledge to reduce the crime rate in the city if elected."
An article in The Union Leader said that he even took a pledge envelope.
On the day, I duly took a pledge to serve Queen and country.
As security, these banks took a pledge on BPI's holding in Antonveneta, the very shares that magistrates subsequently impounded on July 25th.
In the film, Knox seems successful at remaining chaste, but less because she took a pledge than because she has a fearlessly independent mind and the kind of parents who — despite their own conservative leanings — admire her outspokenness.
When British Railways announced its 1955 modernisation plan, the club boasted 230,000 members, who took a pledge not to misbehave or otherwise trespass on railway property following wartime newspaper reports of spotters invading railway tracks.
In the film, Knox seems successful at remaining chaste, but less because she took a pledge than because she has a fearlessly independent mind and the kind of parents who despite their own conservative leanings admire her outspokenness.
Just as we've taken a pledge to care for others, so too should we take a pledge to care for ourselves.
"Now, seven weeks before an election he's taking a pledge," Mr. Torricelli said.
The Republican candidates will be pushed to take a pledge not to issue a federal plan.
It seems that progressives have taken a pledge to be the Washington generals of national politics.
Colorado State University invites students to take a pledge to embrace failure and persist through it.
