I am having a problem with my washer fluid pump on a 1992 Subaru Legacy. The pump quit working during a cold spell but did not work even when the weather warmed. I checked and replaced the fuse, replaced the pump, tested the pump (it worked), tested the power to the pump (it is receiving power), checked the fluid level and the lines (they are working). Since I couldn’t test the ground with the test light, I cut the ground wire and ran it directly to the negative battery terminal. The pump began running constantly, even when the switch was not held on. Is there some intermittent ground for this pump, and how do you fix this without spending $60 an hour for an electrician to troubleshoot this?
On some cars, including my 1978 Oldsmobile Cutlass, the switch onthe the dashboard completes the circuit to the ground. The positive side is always connected to the pump. It sounds as though your Subaru may be set up the same way. I would suspect the switch or the connection from the switch to the ground.