Windshield wipers will only work on high?

It may be the circuit board in the wiper motor or the multi function switch on steering column or the wiper interval module.

Yep I agree the wiper motor is what is to blame when this kind of problem happens, here is how to change it out, next on the list would be the switch but lets try the motor first.

REMOVAL

1. Cycle windshield wipers until they are in straight up position, then turn ignition switch to Off position.
2. Disconnect battery ground cable (two ground cables on diesel engines), then the wiper motor electrical connector.
3. Remove righthand wiper arm and blade assembly, then the righthand pivot nut and allow linkage to drop into cowl.
4. Remove linkage access cover from righthand side of dash panel.
5. Release wiper motor retaining clip, then slide clip back until it clears nib on crank pin, and remove the clip. The wiper motor retaining clip can be reached through the access cover opening.
6. Remove wiper linkage from motor crank pin.
7. Remove motor attaching screws and the motor.

INSTALLATION

1. Install wiper motor and torque attaching screws to 60-85 inch lbs.
2. Connect wiper motor electrical connector, then install clip onto righthand linkage, ensuring clip is fully seated. Do not install linkage on motor crank pin, then attempt to install clip.
3. Install lefthand linkage onto motor crank pin, then the righthand linkage onto crank pin, pulling linkage onto pin until it snaps into place. Clip is properly installed if nib is protruding through center of clip.
4. Install righthand wiper pivot shaft and nut and torque to 84-110 inch lbs.
5. Connect battery ground cable (two ground cables on diesel engines), turn ignition switch to On position, turn wiper switch Off so wiper motor will park, then turn ignition switch to Off position.
6. Install righthand linkage access cover, then the righthand wiper blade and arm assembly and check for proper operation.

Check out the images (below). Please let us know what happens.