I think your wiper relay is down by the park brake, follow the wire from the switch....... I could be wrong.

Old post saved......
After viewing several posts on wiper problems I decided to tackle the "black box" wiper delay control under the dash. After I got the thing out , unplugged, and in my hand I pulled it apart as described in other posts and I found just what I was told I would find, broken solder joints (3) connecting what appears to be a switch/relay mounted on a sheet metal "platform" with 2 "wings" (heat sinks?). The 3 jounts connect the switch and the 2 legs of the "platform" to the circuit board. I re-soldered the connections, flipped the board over and then used JB weld to glue the legs of the "platform" down to the board and used a big dab to glue the side of the platform to the side/end of the black "cube" which sits next to the platform on the board. This glue job will help the platform stay in place under vibration better than the weak solder joints in the stock set up(I hope). Hard to describe but if you open the box (2 screws) you will see what I am describing pretty clearly. I re-assembled the board in to the box, reversed the metal mounting bracket (used same holes in box and bracket but rotated it 180 deg.) Then re-mounted the unit under the dash in a place well away from vibration (I hope). I used a rubber washer (made from an inner tube) between the truck and the mounting bracket this should keep vibration down (I hope). I now have two (2) constant speeds: slow and " a little faster", and I also have my intermittent settings back