i have a 1990 ford econoline van can body tell me where the
intermittent wiper relay is on this model

 

IIRC, it's behind the dashboard near the switch. If the intermittant wipers are not working, I've read it's usually the switch at fault... Mine is not working either... I bought the part but never got around to installing it... The van has other issues right now and I'm not sure what I'm going to do with it.