Try this, disconnect the pump, as you have, put a volt meter on the connector and turn it on. If you get a voltage, and don't blow out the fuse, it's the pump and not the connection.

If it blew the fuse. Did this start after replacing the wiper motor? If you opened up the motor or rebuild it, you may have have installed the internal plastic wheel incorrectly. (in my 240) There were three copper connectors that go in between the plastic wheel. I had the same symptoms when I installed the wheel incorrectly. That may explain why wipers don't end right.

Try disconnecting the wiper motor with the pump connected and see if that blows a fuse. That would rule out a bad wiring harness and indicate the wiper motor. Stock up on fuses I guess.

Try using the intermediate setting with the pump disconnected and see if it blows the fuse. That'd would indicate the motor.

Apart from that, it's very unlikely that the wires harness has gone bad. Check the connector ends, ect ect. I did see a rellay for the motor or washer in my manual.

I just had the washer pump in my kids 86 240 apart, so this may help

After unplugging the pump, hook it up to a 12 volt power source (battery or a charger) Use heavy guage wire. I prefer 12 GA house wire. Hook the wires up to the power source (careful not to let the ends touch) and then stick them into the socket for the pump. See if the pump runs. If it runs, does it pump water? A partially or completely frozen pump or motor will draw excess current and blow your fuse. If it runs and pumps a good amount of water, that is probably not the problem.

If it's frozen, take it back (if new) or take it apart and clean it. Once you disconnect the pump and motor, then rotate the motor by hand to make sure it's OK. If it's hard to turn, try some light machine oil (3 in 1 oil) A 50-50 solution of white vinegar in water is good for mineral deposit buildup in the pump.

If it's not frozen, you should take a current reading on it while it's running. I don't know how to do that, but I'm sure someone else here knows how.