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The switch provides the washer pump power on a brown wire.....So if the brown wire has power leaving the switch which it should then there is a break somewhere in the wire, its usually easier just to run an ew wire.....If its still not pumping when plugged in with voltage then there is probably a kinked line.
Use a testlight at the switch to figure out which wire ONLY has voltage when in wash position, then inspect that wire between switch and pump.
I just looked at the wiring diagrams on a 99 and 01 and they all seem to be the same....My diagrams show a black wire for a ground and a brown wire going from the pump to pin 3 of switch connector. The rear washer power is a black/white wire that goes from the washer pump to pin 2 of the rear wiper switch connector......If wipers work but not pumps it can pretty much only be a wiring problem. Here is the wire diagram I have.