'91 Wipers....???

[CRH]

I've been trying to figure out why the windshield wipers on my 1991 F-350 4x4 only work on high. I've replaced the switch & wiper motor but it still only has high speed. I have a Haynes manual that really doesn't cover much except that it mentions that this truck might have a WCM (wiper control module) behind the glovebox. I've searched for this module if it's there with no success...I'm going by the wire colors at the switch to track down a module. If this truck doesn't have a module then what is telling the wiper motor to operate fast/slow and/or intermittent??
[img]/ubbthreads/images/graemlins/shrug.gif[/img]

[waterdude]

I've already fixed the exact same problem as you are experiencing.

Blame Ford for your problem, for some unknown reason, Ford attached the intermittent wiper module onto the emergency brake [img]/ubbthreads/images/graemlins/shrug.gif[/img] so sooner or later that circuit box gets abused to the point of parts coming unsoldered.

Climb under the dash, remove the black box mounted to the E-brake, open up the black box and resolder the loose connections. Use as little heat as possible to reattach. This module regulated low speed and intermittent wiper speed, without it you only have high speed.

Search: Intermittent Windshield Wiper Problem on this forum over the past 2 years for more info.

--Hugh

[cdnsarguy]

Try this info........Posted by Ken

You have the typical intermitant wiper module failure. The good news is it is an easy fix. Follow the wires off the back of the switch down to the module. The module is located on top of the emergency brake pedal bracket. Once you remove the module open it up carefully. Inside is a circuit board with some electronic components and a couple of relays soldered to it. If you remove this board and flip it over you will find a broken solder joint on one of the relays. Take a soldering iron and resolder it. All Fixed