Wipers dont want to cycle when switched on

[bdydrp97s10]

OK guys. Its been awhile since Ive posted and asked for advice, but these wipers have me stumped and before I go buy a new motor I would like some of the electrical guys to chime in on this issue.

Ive read about 8 posts on the wiper motors on this site and none addressed what my issue is. I may have missed it though.

Heres the issue. I wired my motor the way the posts on here say to wire them, I have the motor that has 3 terminals and no washer pump (I believe to be the round motor). I put my 12 volt hot from the fuse box to the center terminal and ran wires form the two remaining terminals to the switch.

When switched on the motor moves a little but wont rotate. Its like its stuck. If I manually grab the wiper blade and move the arm off of its "park" position the motor will make a full sweep and return to park.

Any Ideas on what could be causing this?

[bdydrp97s10]

For whatever reason when I switched the ignition on today the wipers now magically work, but only in the high speed setting

[VetteVet]

The wiper motors on these trucks are switched on the ground side, so that means you have hot to the motor, and the wiper switch grounds the negative side.
You should be able to check the wiring by checking the middle terminal for 12 volts with the voltmeter. Check the center terminal to any good ground for 12 volts.
Then check the switch by measuring from the center terminal to each end terminal. Turn the switch on and off while looking for 12 volts on the meter. If you get it on each terminal then the switch is good. If not then the switch is not grounding the wires, or the wires are broken between the switch and the motor.

If this checks out then the motor may have a bad park switch but it works in high speed so the motor armature may have a dead spot in it or the motor windings may not be grounded on the low speed side.

I would start with making sure the motor has a good solid ground on the motor body to cab mount. Then do the switch check and if it's good, then you know it's in the motor.
Be sure and clean the wiper fuse holder in the fuse panel so you have a solid 12 volts going to the motor. A poor connection could cause the motor stall or not start.

Good luck.