Interval windshield wiper not working

On my 1984 245 Volvo, the interval wiper function doesn’t work. While troubleshooting, I checked my 1982 245 Volvo and found that the interval wiper works (!!??) even when I disconnected the blue colored relay box found behind the drivers left footrest. So I can’t figure out where the relay is. I can hear it clicking, so it’s down there somewhere, but the blue relay box isn’t it, even thought that box has all the pin numbers that the wiring diagram says it should have. I’m mystified. Can anyone help me? I think I need to replace the relay, if I can find it. Thanks