Wiper Motor Going Bad?

[cygnadu]

Just bought a '70 F-100. The wipers will go on long enough to get into a horizontal position and then stop. They won't move again. Is this a bad wiper motor?

[fordman]

there is a park switch inside th motor. it may be out of sync or soemthing liek that. i forget abotu that. it can be adjusted. there is a thread on the same thing reasently on the site. maybe a month or two old at the most. in this section i think it is.

[knightfire83]

Good point fordman, it could also be the motor's ground or the wiper switch to.

The motor it self is gear reduced. So if it stops in the middle of a wiper sweep, the motor has spun over several times already to get that far. This would indicate that the brushes and windings are ok.

I say the ground because the motor grounds thru it's mounting bolts to the cab. If the mounting surface is rusted or the bolts not tight the motor can shut off mid sweep. This would be from when the motor moves around a bit from the torque on the linkage.

Fordman's suggestion is the most likely culprit. Think this is the thread he was referring to: http://www.fordification.com/forum/view ... or#p418714

[fordman]

i got to thinking abotu this and i may have misdiagnosis this. i am thinking it is a contact for the power or maybe the ground. i knwo the motor ground throught the bolt and tab on the wiper motor bracket. the switch could also be bad. i myslef dotn reall yu se tools to find problems liek this . i have spare parts so i can just swap them and find the problem. but i do not sugject that you go buy parts just to swap them to see if they are broken or not. what i woudl do first i think is to find which wire is sending power to the switch. then find which wires sends power out fromt he switch to the motr. i think it has more than one power wire but i may be wrong. then turn it on. when it quits check to see where the power interutption is at. then go to looking at that parts as your possibly bad part. if it is the motr you can check the park switch in the motor to se if it is adjusted wrong or worn or what has happend. if i ts the switch check into a upgraded wiper switch for delay wipers. oh that reminds me. i need to get wiper blades for the 4wd. thank you.