I am having identical trouble in two trucks. 91' and 98'. The wipers only work in low or high. no intermitent. I replaced the switch in the 98' still same problem. would like to know what it is so I can fix the 91' as well. Anyone out there have this problem? thanks.

 

IF has a wiper motor relay in PDC (?) try swaping the relay with another.
On earlier unit it may well be a switch in the motor.

 

tried swapping out relays. no change. switch inside motor? I am only aware of a ground. Is there any switching that goes on in the motor? I replaced the whole column switch. comes as turn/wiper/brights switch.

 

wow, a stumper..... still fiddlin' with the switch. No change. reground. Bad motor? works though... strange.