[Richard L]

NO, you don't need to ground the blue wire to activate the pump, use the "TST" jumper link. Do not run the test fom more than 10 seconds at a time or you will risk overheating the inline valve (not design to be static).

Grounding the thin blue wire at the relay end is only for diagnostic work. Grounding the thin blue wire energises the 40A relay and power-up the pump.