Well I replaced the wiper delay box (bottom of the steering column) on the 85 K5 and still don't have intermittent wipers. Either full on or off, but nothing in between. Logic tells me that the switch on the column is probably bad too. The delay box obviously had a blown diode in it, but maybe the switch got zapped with whatever surged through the box... or at least that's my theory. Is there anything else in the system that would cause the intermittent wiper settings not to work? Anything in the wiper motor itself? Or are the only two components the delay box and the column switch? Thanks.