Shawski

I have a 90 pickup 22re and in the last week the warning lights have been going on and off. The check engine light is on because my o2 harness is bad, but now the check engine light is going on and off, and when the light goes off, my heater, fuel and temp gauge don't work. I can hear a clicking noise in the comp behind the glove box when this happens as well. I've checked fuses and wiring but cannot seem to locate the problem. Any ideas? Thanks.