He may have used the wrong switch or misconnected the wiring.

As you should know the directional signal and wiper switches are in the
steering column and the stalk is used to control them.

Check under the dash for a single looking wire the exits the steering column
shroud. It really has several wires inside that go to a bayonet type plug.
If any of those wires are broken. The turn signal or wipers will not work.

Hope this helps.

RAD in California